Javascript is currently disabled in your browser. When javascript is disabled, some functions of this website will not work.

Open access for scientific and medical research

From submission to the first editing decision.

From editor acceptance to publication.

The above percentage of manuscripts have been rejected in the past 12 months.

Open access to peer-reviewed scientific and medical journals.

Dove Medical Press is a member of OAI.

Batch reprints for the pharmaceutical industry.

We provide authors with real benefits, including quick processing of papers.

Register your specific details and specific drugs of interest, and we will match the information you provide with articles in our extensive database and send you a PDF copy via email in a timely manner.

Back to Journal »Drug Design, Development and Treatment» Volume 15

Industrial process to improve the efficacy of metformin hydrochloride through the use of factorial experimental design through its paracellular pathway enhancer granulation

Author Mady OY, Al-Shoubki AA, Donia AA

Published on November 2, 2021, the 2021 volume: 15 pages 4469-4487

DOI https://doi.org/10.2147/DDDT.S328262

Single anonymous peer review

Editor approved for publication: Dr. Deng Tuo

Omar Y Mady, 1 Adam A Al-Shoubki, 2 Ahmed A Donia 3 1 Department of Pharmaceutical Technology, Faculty of Pharmacy, Tanta Tanta University, Egypt; 2 Libya Al-Bayda, Department of Pharmacy and Industrial Pharmacy, Faculty of Pharmacy, Omar Al-Mukhtar University; 3 Department of Pharmaceutical Technology, Menoufia University, Shebeen El-Kom, Egypt Mailing address: Omar Y Mady Tel 201141819661 Email [email protected] Adam A Al-Shoubki Pharmaceutics and Industrial Pharmacy Department, Faculty of Pharmacy, Faculty, Omar Al-Mukhtar University, Al- Beida, Libya Tel 218922826802 Email [email protected] Background: Sorbitan monostearate is a surfactant used in the food industry. It is proven to be a penetration enhancer for metformin hydrochloride via the paracellular route. It is solid at room temperature and has a low melting point. Therefore, it was selected as a granulating agent for metformin hydrochloride. Method: A multilevel factorial design was used to determine the optimal formula for industrial processing. Scan the selected recipe using an electron microscope. Differential scanning calorimetry is used to determine the crystalline state of drugs. The author recommends the use of an improved non-eversion capsule technique to evaluate the enhanced penetration of drugs in vitro. To simulate the emulsification effect of bile salts, Tween 80 was added to the perfusion solution. As a pharmacodynamic marker, the blood glucose level of diabetic rats was measured. Results: The results showed that the drug permeability increased in the presence of Tween 80. The drug permeability of the particles is higher than that of the pure medicine or the pure medicine containing Tween 80. The prepared particles lower the blood sugar level of diabetic rats than pure drugs and drugs. Add Tween 80. There is an excellent correlation between the results of the percentage of drug penetration in vitro and the results of the percentage of blood glucose level drop in the body. Conclusion: In addition to the excellent trace characteristics of the prepared drug particles, the improved drug permeability and the drug pharmacodynamic effect showed the dual enhancement effect of the proposed industrial procedure. Therefore, we recommend the same industrial procedure for other Class III drugs. Keywords: sorbitan monostearate, class III drugs, factorial design, modified non-eversion capsule

The Biopharmaceutical Classification System (BCS) is a scientific schematic system that classifies active pharmaceutical ingredients into four categories based on solubility and intestinal permeability parameters. This is because the main factors that determine the rate and extent of drug absorption are its solubility and intestinal permeability. Class I drugs have high water solubility and high intestinal permeability. Class II drugs have high permeability but also low solubility. Compared with class II, class III drugs have high solubility but low permeability. Then, it can be expected that class IV drugs have poor solubility and poor permeability. 1 There are many experiments to increase the solubility of drugs. Self-microemulsifying drug delivery system (SMEDDS) is one of the technologies used to improve the solubility of Class II drugs. It is a pre-concentrated mixture of surfactants, co-surfactants and lipophilic phases. When diluted with water or body fluids in the intestinal cavity, this mixture forms fine emulsion droplets in the size range of 5-100 nm. 2 SMEDDS is also considered to be an ideal carrier for the delivery of class II and class IV drugs. This is due to the improved performance of poorly water-soluble drugs in vitro and in vivo. 3

According to BCS, metformin hydrochloride is a class III drug. It has high water solubility and low intestinal permeability. Therefore, an increase in drug permeability will lead to an increase in its bioavailability, 4 thereby reducing the drug dose. The self-emulsifying drug delivery system (SEDDS) of metformin hydrochloride enhances its intestinal permeability, thereby increasing its oral bioavailability. 5-10

For various reasons, tablets are the most popular pharmaceutical dosage form, including self-administration with accurate dosages to some extent. The drug content and drug content uniformity will be controlled by the pharmaceutical industry within the scope of the pharmacopoeia. The filling of the tablet press mold will determine the weight of the tablet and thus the dose (mg) of the drug. This means that the tablet press uses mold volume (ml3) to express dosage (mg). In most cases, the filling of the tablet press mold will be based on the bulk density of the powder mixture. Some filling machines, especially capsule filling machines, have a screw mechanism that generates a certain pressure during the filling process to squeeze the powder to increase the amount of powder in the capsule shell. This means that the filling process changes from the bulk density to a certain degree of tap density. The uniformity of the tablet weight and therefore the uniformity of the drug content depends on the powder flowability, bulk density and particle size range. The above-mentioned technical problems of each drug can be overcome by using a suitable granulation technique to change the powder form of the drug into particles with a narrow particle size range. Metformin hydrochloride is one of the most commonly used high-dose (500, 850 and 1000 mg) oral hypoglycemic agents. It has poor fluidity and poor compression properties, and its high dosage will cause formulation problems. 11

A review of various literature shows that there are many trials involving the granulation of metformin to improve its microscopic properties. Different granulation technologies are used, such as wet granulation technology12,13 and melt granulation technology14-17. Aodah et al., 2020,18 also proposed an improved wet granulation technology, as a test to reduce the wet granulation step, and may also help reduce the degradation of the drug in the drying step of wet granules. 18 Sorbitol monostearate (Span-60) is an ester of sorbitol derivative and stearic acid. It is mainly used as an emulsifier and is approved by the European Union as a food additive emulsifier. 19,20 In addition, due to long-term toxicity studies, it is considered safe for human use and shows no signs of carcinogenic activity. Human body at different dosage levels. 21,22 Pardakhty, 2017,23 reported that

Sorbitan monostearate is a better surfactant for noise formulations. The high phase transition temperature, low hydrophilic-lipophilic balance and critical packing factor of sorbitan monostearate resulted in spherical vesicles of good size. twenty three

Mady24 successfully used sorbitan monostearate as a microsphere matrix prepared by coagulation technology and solvent evaporation technology. 24 This may be due to its low melting point and solid state properties at room temperature. Also studied is the use of glyceryl monostearate or stearic acid to make paracetamol into granules to improve its compressibility. The results showed that the compressibility of the standard drug for incompressibility (paracetamol) was improved. In addition, the ability of using glycerol monostearate to form spherical particles is also shown. 25 Recently, Mady et al.26 successfully enhanced the permeability of metformin hydrochloride by using sorbitan monostearate as a microparticle matrix. 26 The drug enhancement mechanism is the absorption mechanism through the paracellular pathway. Therefore, this study aims to use the lower melting point and room temperature solid characteristics of sorbitan monostearate to granulate metformin hydrochloride using the melting and solidification technology suggested by the author. The factorial experimental design will be used to study different granulation factors using the required drug processing characteristics as indicators. Some instrumental analysis should be used to characterize the drug in the prepared particles. Then, the effect of sorbitan monostearate as a surfactant on the dissolution and permeability of the drug in vitro was studied. Improved drug permeability in vitro should also be confirmed by in vivo tests as a test to confirm enhanced drug permeability.

Metformin hydrochloride (El-Nasr Pharmaceutical Chemicals Co, Egypt), n-octanol (Loba Chemie, India), sorbitan monostearate and Tween 80 (Oxford, Lab Chem, Mumbai, India), phosphoric acid Disodium monohydrogen and potassium dihydrogen phosphate were purchased from El-Gomhoria Chemical Company (Tanta City Branch, Egypt). All other reagents and chemicals used are of analytical grade.

The granulation process of metformin hydrochloride is optimized through the use of multilevel factorial design (41, 22). The software used is MINITAB, version 17. Table 1 shows that the selected independent variables are the concentration of the four levels of granulating agent (sorbitan monostearate), the granulation temperature and the stirring rate of each of the two levels. The dependent variables tested are the angle of repose, compression index and average particle size. Experimental trials were performed under all 16 possible combinations (Table 2). Table 1 Application of (41, 22) multi-level factorial design variable coding unit and its grade Table 2 Design matrix of the prepared granule dosage form

Table 1 (41, 22) Variable coding units and levels used in multi-level factorial design

Table 2 Design matrix of prepared granule formulation

According to Table 2, a physical mixture (20 g) of metformin hydrochloride and sorbitan monostearate was prepared. A mechanical stirrer (Heidolph, Germany) with a locally manufactured planetary mixer shaft was used to stir each physical mixture at room temperature for 5 minutes. The stirring speed and temperature of the prepared physical mixture were adopted according to Table 2, stirring for 15 minutes. Then, the temperature was lowered while stirring at the same stirring speed as room temperature. The prepared particles were collected and stored at room temperature for further research.

The flow characteristics of different products are measured by the angle of repose method. In all experiments, the funnel was kept at a fixed height. The sample passes through the funnel to form a stable cone. 27 The angle of repose (θ) is calculated using formula 1: (1)

Where θ = angle of repose, h = height of cone, r = radius of cone base.

Carefully place the 10 g sample into a 50 mL graduated cylinder. The volume (V0) is measured in cm3. The fixed cylinder falls from a height of 2.5 cm at one-second intervals. 28 Keep tapping until no further changes in volume are noticed. The measured volume (Vt) cm 3.28 Calculate the different parameters of the particles according to the formula (2-4): (2) (3) (4)

The average particle size of the particles is determined by using a sieving method. A certain weight of particles is placed on a set of standard sieves, and a mechanical vibrating sieve is used to automatically vibrate at a constant speed for 10 minutes. Weigh the part of the particles remaining on the sieve to determine the particle size distribution. 25 The average particle diameter is calculated using formula 5.29 (5)

The exact weight of metformin hydrochloride granules (100 mg) of different particle sizes (1000 µm, 800 µm, 315 µm and 106 µm) prepared with different concentrations of granulating agents were dissolved in 100 mL 0.1 N HCl at 60°C. Using 0.1 N HCl as a blank, the prepared solution was measured spectrophotometrically at 232 nm. It is also proved that the presence of sorbitan monostearate in the solution does not affect the absorbance of the drug. This procedure was performed in triplicate. 30 Use equations (6 and 7) to calculate the average actual drug content:

Theoretical Drug Content (TDC) (6)

Actual drug content (ADC) (7)

The exact weight of the prepared sorbitan monostearate granules is added to the Paddle USP Dissolution Apparatus Type Dis 6000 (Copley Scientific, UK). The release medium is 900 mL 0.1N HCl, and the temperature is maintained at 37 ± 0.5°C. At predetermined intervals, 5 mL of samples are drawn for analysis, and 5 mL of fresh release medium is added to supplement each sample drawn. A UV/Visible spectrophotometer (Thermo Fisher Scientific, EVO 300PC, software: vision pro, USA) was used to determine the drug content of the sample by spectrophotometry at 232 nm. Three repetitions were made. 31

Thermal analysis of metformin hydrochloride and different concentrations of sorbitan monostearate-metformin hydrochloride granules was carried out. The heating range is between 20 and 240°C. This is to cover the melting point of the pure drug, which is reported to be 225°C. 32 For thermal analysis, use DSC (PerkinElmer Synchronous Thermal Analyzer SAT 6000, provided) to simultaneously perform Differential Scanning Calorimeter (DSC) for each sample using software: Pyris SAT 6000, USA). 32

Scanning electron microscope [ESM] (JEOL model: JSM-5200LV, Japan) is used to study the morphology and surface of prepared sorbitan monostearate-metformin hydrochloride particles. Try to clarify the shape of the particles and the method of agglomeration to obtain the best vision by using different magnifications.

Use the MINITAB software to perform statistical analysis on the predetermined parameters. The software has been licensed to Adam A. Al-Shoubki, product version: (Minitab® 17.3.1). The factorial design is statistically analyzed by multiple regression analysis. A statistical model containing interaction terms and polynomial terms is used to evaluate the response (Equation 9): (8)

Where Y is the dependent variable, b0 is the arithmetic average response of 16 runs, and bi is the estimated coefficient of factor i. The average effect (A, B, and C) represents the average result of changing one factor from a low level to a high level at a time. The interaction terms (AB, AC, and BC) show how the response changes when the two factors change at the same time. A two-way analysis of variance at the 95% significance level (p<0.05) is used to evaluate the significance, the validation of the selected formula, and the contribution of each factor at different levels to the response. 33

A certain amount (20 mg) of the pure drug or each drug granulated with sorbitan monostearate was dissolved in n-octanol. While stirring, add distilled water (20 mL). Transfer the prepared solution to a separatory funnel and allow it to equilibrate. The drug concentration in the aqueous solution was measured by spectrophotometry at 232 λ max. log P is calculated according to Equation 9: (9)

The method step used to evaluate the drug permeability curve from the modified non-eversion capsule method is the modified experimental procedure described in the reference. 34-36

Preparation of non-inverted intestinal sac: The animal used in this study was a male albino rabbit weighing 2 kg obtained from the Tanta animal house. All procedures were approved and regularly controlled by the Animal Ethics Committee of the School of Pharmacy of Tanta University (No. 2212018), and all experiments were carried out in accordance with the guidelines and regulations of the committee. All procedures are also carried out in full accordance with ARRIVE guidelines 2020,37, and adequate measures have been taken to minimize animal pain and discomfort. They live in a clean room and have free food and water. Instead of eating overnight with free water, they were anesthetized by intramuscular injection of ketamine hydrochloride. The animals were sacrificed after confirming the disappearance of the pain response. Make a 3-4 cm midline longitudinal incision to locate the small intestine. Flush the sac of the 14 cm intestinal segment with pH 6.8 phosphate buffer to remove any solid matter, and tie the side of the small intestine segment with a surgical thread. In order to check for leaks, the fresh intestinal sac was filled with pH 6.8 phosphate buffer, which was tied to the other side with surgical thread and checked. The fragments prepared after each step were placed in a continuous aerated phosphate buffer pH 6.8 and used to study drug permeation on the same day after filling the perfusion solution.

Preparation of perfusion solution and filling of non-eversion capsule: accurately weigh sorbitan monostearate particles containing 50 mg of metformin hydrochloride as the actual drug content. Dissolve the sample in 3 mL of pH 6.8 phosphate buffer, and then add 1 mL of Tween 80. Tween 80 was added to simulate the effect of bile salts on drug absorption. After emptying the fresh intestinal sac segment from the buffer, fill the intestinal sac with the prepared perfusate, tie it with a surgical thread, and conduct a leak test. For calculation, the length and diameter of the permeability section are measured.

Drug penetration curve study: Hang the prepared fragments on the shaft of the USP dissolution apparatus. The extracapsular medium [permeable medium] is 900mL phosphate buffer [pH 6.8], continuously aerated, and the temperature is kept at 37±0.5°C. The stirring speed is 50 rpm. Take 5 mL samples at predetermined time intervals and add fresh release medium to supplement each sample taken. At 232 λ max.19, the amount of drug permeated from the fragment into the medium was determined spectrophotometrically. The validation data of the analytical method are as follows: R2 value is 0.999, linearity is between 2 and 20 μg/mL (used range), precision when RSD% value is less than 2%, accuracy is determined by recovery rate (99.72-100.81%) confirm.

Determination of permeability coefficient: The permeability coefficient [apparent permeability] is determined in the isolated rat intestine by using Fick's law. 38 The law is described mathematically as (Equation 10): (10)

Where dM/dt is the number of moles of solute transported per unit time, P is the permeability coefficient, S is the surface area of ​​the membrane, Cd is the solute concentration in the donor [serous membrane] phase, and Cr is the solute concentration in the acceptor [mucosa] stage. In this case, the sink condition is dominant, because the volume of the slurry is much larger than the mucosal volume, then Cd is constant, much larger than Cr, and Cr is negligible. Therefore, the equation can be written as Equation 11: (11)

The variables M and Cd can be determined by analyzing mucosal fluid. The surface area [S] can be calculated by considering the intestinal sac as a cylinder. Based on these values, M/SCd can be calculated and plotted against time. The slope of the linear part of the graph is the permeability coefficient [P], and its unit is velocity [cm/s]. The slope of the linear part of the curve is determined by linear regression. 39,40

The animals used in this study are male albino Wistar rats aged 7-8 weeks, weighing 150-200 grams. All procedures were approved and regularly controlled by the Animal Ethics Committee of the School of Pharmacy of Tanta University (No. 2212018), and all experiments were carried out in accordance with the guidelines and regulations of the committee. All procedures are also carried out in full accordance with ARRIVE guidelines 2020,37, and adequate measures have been taken to minimize animal pain and discomfort. The animal's breeding environment has a temperature of 25±1°C, a relative humidity of 45-55%, and a light and dark cycle of 12 hours each. They are fed pellets and water at will.

The animals did not eat overnight. Diabetes was induced by a single intraperitoneal injection of a freshly prepared streptozotocin solution (50 mg/kg body weight) in 0.1 M citrate buffer (pH 4.5). In order to overcome the blood sugar lowering effect of the drug, animals can drink a 5% glucose solution. On the 3rd day after the injection of streptozotocin, the rats were fasted for 6 hours, and blood was drawn from the tail vein. Use Accu-Chek Activity Test Strips Use Accu-Chek Activity Test Strips to measure blood glucose levels. Rats with fasting blood glucose levels >250 mg/dl are considered to have diabetes and are used to monitor the efficacy of metformin preparations.

On the day of the experiment, the rats were allowed to freely contact the particles for 15 minutes. After that, food is restricted, but you can drink water for free for 2 hours. That is to provide a stable level of glucose in the blood of rats. The preparation was dispersed in water at a concentration of 30 mg/mL, and 0.125 mL of Tween 80 was added per mL. Then, 1 mL of the prepared test dispersion was orally administered to each rat. Blood samples were drawn from the tail vein at intervals of (0, 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7, and 8) hours. Use Accu-Chek test strips to measure blood glucose. The percentage drop in blood glucose levels was also calculated and plotted as a function of time. The area above the curve is determined and used to monitor the efficacy of the different formulations. 41

A one-way analysis of variance (ANOVA) test was performed to prove the statistical significance of the blood glucose level as an independent factor. GraphPad Prism version 8.0.1 for Windows (GraphPad Software, San Diego, California, USA, www.graphpad.com) is used for this purpose. P <0.05 was considered statistically significant.

In order to study the influence of each factor on the response, the micro-degree characteristics of the prepared particles were assigned to all formulas, as shown in Table 3. Table 3 Summary of optimized response

Table 3 Summary of optimized responses

The value of the angle of repose is between 28.072° and 32.828° (Table 4), indicating that the flow of all prepared particles is very free-flowing or free-flowing. Table 4 In vitro characterization of all granular formulations

Table 4 In vitro characterization of all granular formulations

Evaluate the relationship between the response Y1 (angle of repose) and the independent variables (A, B, C, AB, AC, and BC) by using stepwise multiple linear regression. The result is reported in Equation 12: (12)

Regression analysis shows that factor A and interaction AB have the only significant effect on the angle of repose value (p <0.05). The most effective factor is A, and its coefficient value is negative, indicating that a high concentration (20%) of sorbitan monostearate significantly reduces the angle of repose. The factor with the greatest interaction is AB, and the coefficient value is positive, indicating that they use a high concentration of sorbitan monostearate (20%) and high temperature (80°C). Therefore, the optimal formula conditions for the angle of repose are high sorbitan monostearate concentration (20%) at (80°C) and 100 or 200 rpm (formula, F15 and F16). First, a physical mixture between the drug and sorbitan monostearate is prepared at room temperature to ensure that the granulating agent and the drug crystals are uniformly mixed. Increasing the temperature causes the adhesive to melt. The molten liquid is distributed on the surface of the fine solid drug crystals, thereby forming crystal nuclei through the distribution method. The nucleus is formed by collisions between wetted particles. The residual surface liquid of the adhesive promotes the successful fusion of the nuclei (Figure 1B and D). The surface liquid imparts plasticity to the crystal nucleus and is also indispensable for deforming the surface of the crystal nucleus for coalescence and promoting roundness of granulation. This can be noticed from the ESM of F16 (Figure 1B and D). Therefore, by covering the drug crystals with sorbitan monostearate as the initiator of the granulation process, and then aggregating the covered drug crystals into particles, it can be expected that the value of the angle of repose will be improved. The proposed granulation mechanism depends on the concentration of sorbitan monostearate, which must be melted while stirring to cover the drug crystal particles. Figure 1 Electron scanning microscope photograph (ESM). (A and C) show formula 12 at ×35 and ×100 magnifications respectively; (B and D) show formula 16 at ×35 and ×100 magnifications respectively; (EG) respectively show the formula at 35 times magnification Formulation 4 Formulation 8 and pure medicine.

Figure 1 Electron scanning microscope photograph (ESM). (A and C) show formula 12 at ×35 and ×100 magnifications respectively; (B and D) show formula 16 at ×35 and ×100 magnifications respectively; (EG) respectively show the formula at 35 times magnification Formulation 4 Formulation 8 and pure medicine.

Table 4 summarizes the average compression index (%) values ​​of all granular formulations. The regression equation in response to Y2 (compressibility index) and independent variables (A, B, C, AB, AC, and BC) is shown in Equation 13. (13)

Regression analysis revealed the significant influence of all tested factors and interactions on the compression index (%) except for the interaction between AB and AC (p<0.05). The most effective factor is negative C (stirring speed). In other words, it may be due to increased particle uniformity (Figure 1A-D). The second and third effective factors are negative B (temperature) and negative A (sorbitan monostearate concentration), respectively. These results show that the optimal formula condition for compression index (%) is (F16), which is formulated with high concentration of sorbitan monostearate (20%) at (80°C) and (200 rpm) of.

For tablet manufacturing, the powder should be in the particle size range of 0.2-4.0 mm. They are mainly produced as intermediates, with a size range of 0.2-0.5 mm, and can be packaged as a dosage form or mixed with other excipients before tableting. 42 As a new application of sorbitan monostearate as a granulating agent, the average particle size was also selected as the response to the granulation process. The stepwise multiple linear regression equation (Equation 14) in response to Y3 (average particle size) is (14)

Regression analysis revealed the significant influence of all tested factors and interactions (p <0.05) on the average particle size value except for factor B and interaction AB. In other words, it may be that the temperature of the powder alone is increased, and it cannot be expected to increase its average particle size. In addition, when melting without stirring, increasing the temperature of the powder in the presence of sorbitan monostearate as a granulating agent has no effect on the average particle size as an interaction. The most effective factor is positive A (sorbitan monostearate concentration). The second effective factor is negative C (stirring speed). These results indicate that the optimal formulation conditions for increasing the average particle size are high sorbitan monostearate concentration (20%) at 200 rpm and (60°C or 80°C) formulations (F14, F16).

Regression analysis of the three factors of angle of repose, compression index and average particle size shows that the best formula is F15 (Table 5). Then, the best granulation procedure is to use 20% granulation agent (high level), temperature of 80 °C (high level) and 100 rpm stirring rate (low level). Table 5 The best formula for all responses (F15)

Table 5 The best formula for all responses (F15)

These results can be considered consistent with the granulation process, because increasing the concentration of the granulating agent will increase the efficiency of the granulation process (Figure 1A-F. The high temperature keeps the granulating agent in a molten state, which enhances its ability to start granulating. During the effect, the melted droplets fuse and round the particles. In addition, the low stirring rate causes the particle size to increase.

Figures 1A-G show scanning electron microscope images of different metformin hydrochloride particles prepared using different concentrations of sorbitan monostearate and pure drugs. Comparing the ESM of the pure drug (Figure 1G) and the ESM of the granules (Figure 1A-F), it can be concluded that due to the use of sorbitan monostearate as the aggregating agent, the drug crystals aggregate into particles. In addition, it can be noted that as the concentration of the granulating agent increases, the particle size of the particles also increases. In other words, it may be due to the increased coverage of the molten sorbitan monostearate on the drug crystals, and the drug crystals aggregate to form nuclei through a distribution mechanism.

Table 6 shows the average actual drug content of all the prepared metformin particles. It can be seen from the table that the theoretical value (TDC) and the average actual drug content (ADC) value are closest to each other. In addition, except for the case of using 20% ​​sorbitan monostearate as a granulating agent, the ACD of the four particle size fractions of the prepared particles showed that the ADC was increased by reducing the particle size. The use of 5%, 10%, and 15% of granulating agents increased ACD with decreasing particle size, indicating that the amount of sorbitan monostearate was insufficient to granulate the amount of drug used. Table 6 The actual drug content of all preparations

Table 6 The actual drug content of all preparations

The partition coefficient is a parameter used to express the lipophilicity of a drug. Since metformin hydrochloride is granulated from sorbitan monostearate, it is necessary to measure the effect of different concentrations of granulating agent on the lipophilicity of drug particles. From (Table 7) we can notice that the value of the partition coefficient is increased by increasing the concentration of the granulating agent. Increasing the partition coefficient of granular metformin, which increases with the increase of the granulating agent concentration, indicates that the lipophilicity of the granular hydrophilic drug and sorbitan monostearate increases. This leads to an expected increase in the permeability of the drug, thereby increasing its pharmacodynamic effect. 43 Table 7 Log P values ​​of pure drugs and drug particles

Table 7 Log P values ​​of pure drugs and drug particles

The drug release curves of particles with the same particle size range prepared with different concentrations of sorbitan monostearate were studied (Figure 2). It can be seen from the figure that there is a burst effect and incomplete drug release. These two effects depend on the concentration of sorbitan monostearate used. Increasing the concentration of the granulating agent resulted in a burst effect and a decrease in the total drug release during the dissolution process. That is to say, it may be due to the coating effect of the sorbitan monostearate of the drug crystals and the insolubility of sorbitan monostearate in the dissolution medium. These results are consistent with the proposed granulation mechanism, which is started by melting the granulating agent covering the drug crystals. Increasing the concentration of sorbitan monostearate results in a good coating of the drug crystals, which results in a reduced bursting effect and incomplete release. The high solubility of the drug in the dissolution medium can also confirm this explanation, which can also be noticed from the dissolution profile of non-granular pure drug crystals. Figure 2 In vitro release curve of pure metformin hydrochloride and drug particles (n=3).

Figure 2 In vitro release curve of pure metformin hydrochloride and drug particles (n=3).

Figure 3 shows the DSC thermograms of different particles prepared with pure metformin hydrochloride and different concentrations of sorbitan monostearate (F2, F4, F14, and F16). It can be seen from the figure that the thermogram of pure metformin hydrochloride shows an obvious endothermic transition stage, with the highest temperature of 224.68 °C. This endothermic transformation stage is attributed to the melting of pure metformin hydrochloride. 32 A huge endothermic peak was also observed directly after the melting of pure metformin hydrochloride, which was due to the decomposition of the pure drug. 44 More detailed information about heat also reported the degradation of metformin hydrochloride. 45 Comparing the DSC scan of the drug in the prepared granules with the DSC scan of the pure drug, it can be concluded that due to the granulation process, the crystallinity of the drug and the crystallinity of the pure drug have not changed. In addition, (F2, F4, F14 and The DSC scan of F16) showed an endothermic peak near 60°C, which increased with the increase of the concentration of sorbitan monostearate. This endothermic peak represents the melting point of sorbitan monostearate. These results are consistent with the scanning electron microscopy results of the same product, showing that the drug crystals are coated with the granulating agent. Figure 3 Differential scanning calorimetry (DSC) thermogram of pure metformin HCl and (F2, F4, F14 and F16).

Figure 3 Differential scanning calorimetry (DSC) thermogram of pure metformin HCl and (F2, F4, F14 and F16).

The use of "intestinal sacs" to determine permeability is a fast and sensitive technique to determine the overall intestinal integrity of specific molecules or to compare transport, and has the additional benefit of intestinal site specificity. The apparent permeability [Papp] or permeability coefficient of a molecule through the intestinal barrier can be calculated. 46

From Figure 4, you can notice the effect of adding Tween 80 to the drug on its permeation curve, involving the initial permeation rate, and total drug permeation during the experimental time. This effect is significantly increased from the drug particles. The initial drug penetration increased slightly. At the same time, the rate and total amount of drug penetration increased significantly after 1 hour. Using 20% ​​sorbitan monostearate as a granulating agent increased the drug penetration curve compared to 5%. Figure 4 Permeability curves of pure drugs and selected formulations (n=3).

Figure 4 Permeability curves of pure drugs and selected formulations (n=3).

The permeability parameters of metformin hydrochloride, metformin-Tween 80 and selected metformin-sorbitan monostearate particles through the non-eversion capsule were determined, and the results are summarized in Table 8. It can be seen from Table 8 that R2 is high enough in each case to allow for a good fit of the data. In addition, in each case, there is no lag time, instead there is an intercept value with a concentration of y abscissa (Table 8). There is no lag time, which may be due to the high water solubility of the drug, which may be the reason for the intercept value. In this case, the intercept value indicates that the paracellular pathway tissue of the intestinal wall is rapidly saturated with the drug before the drug is transported. This result is supported by the fact that approximately 90% of metformin hydrochloride is absorbed through the paracellular route. 47-49 The addition of Tween 80 to the drug resulted in an increase in all drug penetration parameters. In other words, it may be due to the effect of non-ionic surfactants on the absorption of metformin through the paracellular pathway. In addition, the important saturable components of the paracellular pathway may be affected by the presence of Tween 80, especially mediated by the electrostatic interaction between the opposite charges of the diffusing substances (drugs and Tween 80) and the anionic residues in the lateral space. Can saturate paracellular pathways. / Or tightly connected. 47 In addition, it can be noted from the same table that the emulsification of metformin-sorbitan monostearate granules by Tween 80 resulted in a significant increase in the apparent permeability of the granular drug compared with the drug alone or the drug-Tween. . Table 8 Data on transfer of metformin hydrochloride through non-inverted intestinal sac (n=3)

Table 8 Data on transfer of metformin hydrochloride through non-inverted intestinal sac (n=3)

The apparent permeability of the drug, drug-Tween and different concentrations of sorbitan monostearate particles are also shown in Figure 5. It can be seen from the figure that the penetration enhancement of drugs can be sorted as follows, drug particles ˃ drug Tween ˃ individual drugs. Therefore, it is reported that the granulation of the drug and the emulsification of the prepared particles by sorbitol monostearate results in the penetration enhancement of the drug. The increase in drug permeability may lead to a decrease in the recommended drug dose, thereby causing its side effects, which is a particularly known problem for elderly patients. Figure 5 Apparent permeability (mucosal to serous membrane) of pure drug and selected formulations (n=3) of metformin.

Figure 5 Apparent permeability (mucosal to serous membrane) of pure drug and selected formulations (n=3) of metformin.

Monitoring the parameters of drug efficacy markers represents the evaluation of the in vivo performance of different classes of drugs. It measures the pharmacological effects of a drug, which is the reason for its appreciation and/or application. Metformin hydrochloride is an oral hypoglycemic agent used to lower blood sugar levels. Therefore, measuring the blood glucose level after oral administration of the drug can be used as a pharmacodynamic index parameter to evaluate the in vivo performance of metformin hydrochloride in the particles prepared compared with the pure drug.

Before administration, the blood glucose level is measured, which represents the zero hour blood glucose level. Then, the drug is administered and the plasma glucose level is monitored as a function of time. The blood glucose level will be expressed as a decrease in the blood glucose level, and the decreasing curve of the drug glucose concentration will be plotted as a function of time (Figure 6A). Figure 6 (A) Glucose level (mg/dl) versus time curve (SD error bar), (n=6). (B) Glucose level (mg/dl) versus time curve (SD error bar), (n=6).

Figure 6 (A) Glucose level (mg/dl) versus time curve (SD error bar), (n=6). (B) Glucose level (mg/dl) versus time curve (SD error bar), (n=6).

The drop in the blood glucose level curve indicates a slight drop in the blood glucose level in the previous hour, which is consistent with the results of the penetration curve. It can be noticed that blood glucose levels decrease when the oral drug starts to take effect 15 minutes after administration. This is due to the high solubility of the drug and its main absorption mechanism (paracellular pathway). Then, the speed and maximum amount of blood glucose drop are significant, which can be arranged separately from F16˃F4˃Drug-tween˃Drug as follows. Each point represents the average of the blood glucose level measurement at that time, and the standard deviation is shown in Figure 6B.

In addition, according to the figure (6A and B), calculate the area above the curve, which is listed in Table 9 and used for comparison. It can be concluded from the table that after adding Tween 80 to the drug, its medicinal effect is increased by 20% (calculated by dividing by the difference between the area above the drug-Tween curve and the area above the drug alone). The use of Tween 80 emulsified metformin hydrochloride granules increased the pharmacodynamics of the drug by 43%, which represents the additional effect of the presence of sorbitan monostearate. Statistical analysis of the data (ANOVA test) showed that compared with the control (metformin hydrochloride alone), at P 0.05, the pharmacodynamic effects of metformin hydrochloride and Tween and granules were significantly enhanced after oral administration. Table 9 Blood glucose levels after oral administration in diabetic rats

Table 9 Blood glucose levels after oral administration in diabetic rats

The advantages of drug particles over pure drugs, in terms of the onset of action and the area above the curve, indicate that the granulation of sorbitan monostearate to the drug improves the speed and extent of drug absorption. Compared with the pure drug, the increase of drug absorption rate indicates the enhancement of drug penetration, which is proved by the modified non-eversion capsule test. The enhancement of drug permeability leads to the enhancement of drug bioavailability, which will be reflected in the pharmacodynamics of the drug. This theoretical concept has now also been approved by in vivo experiments. This discovery should lead to a reduction in the recommended dosage of the drug under the application of the recommended industrial procedures, thereby reducing drug side effects.

Metformin hydrochloride is a class III drug that faces penetration problems. The bioavailability of metformin hydrochloride is 40-60%. The modified non-eversion capsule study showed that within 8 hours, the total drug permeability increased from 21.86 ±0.222 for pure drug to 45.48 ±1.156 and 59.124 ±0.228 for F4 and F16, respectively. At the same time, the blood sugar level (pharmacodynamics) decreased by 43% compared with pure medicine.

The binding of metformin to plasma proteins is negligible. It will be excreted in the urine in its original form and will not be metabolized by the liver. 51 It is mainly absorbed through paracellular pathways. 50 According to reports, the Liquisolid system and SEDDS can enhance the dissolution and bioavailability of lipophilic drugs (such as simvastatin and famotidine), and are tested in vitro and in vivo. 48,49 In this study, the granulation of metformin with sorbitan monostearate caused its solubility in water to decrease and increase its partition coefficient (lipophilicity). The drug particles prepared by using sorbitan monostearate as a granulating agent have greater drug permeability and efficacy. This is because sorbitan monostearate enhances the paracellular pathway penetration of the drug, thereby improving the pharmacodynamic effect of the drug. Therefore, according to reports, the author recommends the use of fusion coagulation technology to granulate metformin hydrochloride and sorbitan monostearate, resulting in a double effect of surfactants used in food on the drug: first; excellent improvement of the drug’s trace characteristics This represented the first industrial problem faced by pharmaceutical preparations in a large number of literature tests, and secondly; the use of sorbitan monostearate as a granulating agent increased its permeability, thereby increasing its bioavailability. This may lead to studies of pharmacokinetics, reduction of recommended drug doses, and of course drug side effects.

The term correlation is often used in pharmaceuticals and related sciences to specify the relationships that exist between variables. From a mathematical point of view, the term correlation means the interdependence between quantitative or qualitative data or the relationship between measurable variables and levels.

The FDA defines IVIVC as a "predictive mathematical model describing the relationship between the in vitro characteristics of a dosage form and related in vivo reactions." Generally speaking, the in vitro characteristic is the rate or extent of drug dissolution or release. However, the in vivo reaction is the plasma drug concentration or the amount of drug absorbed. 52,53 FDA regulations describe the 4 levels of IVIVC, which are A, B, C, and multiple Cs. 54 Level A is related to personal data related to the whole in vitro and in vivo. It represents the point-to-point relationship between the in vitro dissolution rate and the in vivo infusion rate of the drug from the dosage form. 46 Therefore, it is the most relevant category.

In this study, we tried to correlate the drug penetration curve data of the rabbit intestinal sac with the pharmacodynamic response of the drug to diabetic male rats (Figure 7 and Table 10). It can be seen from the figure that the drug penetration curve of the rabbit intestinal sac is almost opposite to the drug effect curve of the drug in male rats. In other words, it may be because there is a correlation between drug permeability and pharmacodynamics. The medicinal effect is to reduce the blood sugar level by %. Each time, increasing the percentage of drug penetration will cause the percentage of blood glucose levels to drop. Since the A-level correlation is a linear relationship between two variables, an attempt was made to establish a mathematical line correlation between the drug penetration percentage and its pharmacodynamic effect (decrease in glucose level) as a point-to-point correlation. The results are summarized in (Table 10). It can be seen from the table that the value of R2 is high enough to conclude that there is an excellent correlation between the variables. The intercept values ​​are almost equal and close to 100%. The ratio (slope) of the correlation value increases as the amount of sorbitan monostearate in the particles increases, which is consistent with the enhanced penetration of sorbitan monostearate to the drug. These results may indicate that the authors recommend the use of a modified non-eversion capsule as a technique for predicting the process of drug penetration in vitro. The non-eversion sac of the intestine should be suspended in the shaft of the dissolution apparatus to avoid the retention of the diffusion layer. The dissolution medium is stirred by the shaft of the stirring device to represent the circular motion of the blood. 26 Table 10 Related data of drug penetration and pharmacodynamic curve Figure 7 Point-to-point (level A) correlation of drug penetration curve and its pharmacodynamic effect: (A) Metformin hydrochloride, (B) Metformin hydrochloride plus Tween 80, ( C) Formula F4, (D) Formula F16.

Table 10 Data related to drug penetration and pharmacodynamic curve

Figure 7 Point-to-point correlation between drug penetration curves and their pharmacodynamic effects (level A): (A) metformin hydrochloride, (B) metformin hydrochloride plus Tween 80, (C) formula F4, (D) formula F16.

From this study, it can be concluded that the use of sorbitan monostearate, which is commonly used in the food industry, as a granulating agent leads to the formation of free-flowing, good compressibility and narrow particle size particles. These physical properties are very important for packaging, transportation and tablet presses in the pharmaceutical industry. In addition, it has been found that the use of sorbitan monostearate improves the permeability of class III model drugs. The suspension of the non-eversion capsule on the shaft of the dissolution apparatus prevents the formation of a stagnant diffusion layer. This may lead to an excellent correlation between the results of drug penetration of the modified non-eversion capsule and the decrease in blood glucose levels (improving the pharmacodynamic response of the drug). Therefore, it is reported that the author recommends the use of fusion coagulation technology to granulate metformin hydrochloride and sorbitan monostearate, resulting in a double effect of surfactants used in foods on the drug: first; excellent improvement in the microscopic properties of the drug This represents the solution to the first industrial problem faced by pharmaceutical formulations in many literature tests, and the second; the use of sorbitan monostearate as a granulating agent improves its permeability and thereby improves its bioavailability. This may result in lower recommended drug doses after pharmacokinetic studies, and of course drug side effects. Therefore, it is strongly recommended to use the same technology and the same procedure to solve the penetration problem of class III drugs, especially because the granulation process is easy, repeatable, cheap and suitable for the pharmaceutical industry.

The original data supporting the conclusions of this manuscript will be provided by the author Adam A. Al-Shoubki (email: [email protected]) to any qualified researcher.

All animal research procedures are approved and regularly controlled by the Animal Ethics Committee of the School of Pharmacy of Tanta University (No. 2212018), and all experiments are carried out in accordance with the guidelines and regulations of the committee. All procedures are also carried out in full accordance with ARRIVE guidelines 2020.37

We must thank the staff and faculty of the Department of Pharmaceutical Technology, School of Pharmacy, Tanta University, for sharing their pearls of wisdom with us during this research. The abstract of the paper was published at the 35th Scientific Conference of the Egyptian Pharmaceutical Society in Cairo, Egypt, as an interim result of the conference talks. The author shared the abstract on the ResearchGate platform: https://www.researchgate.net/publication/340095954_An_industrial_procedure_for_pharmacodynamic_improvement_of_metformin_HCl_via_granulation_with_its_Paracellular_pathway_enhancer

The author declares that there is no competing interest in this work.

1. Sharma S, Prasad B. Predict the negative effects of food on drug bioavailability through a physiologically-based pharmacokinetic model guided by the Mechanical Biopharmaceutical Classification System (mBCS). FASEB J. 2020;34(S1):1. doi:10.1096/fasebj.2020.34.s1.05705

2. Cho YD, Park YJ. In vitro and in vivo evaluation of the self-microemulsifying drug delivery system of the poorly soluble drug fenofibrate. Arch Pharm Res. 2013;37(2):193-203. doi:10.1007/s12272-013-0169-4

3. Yan B, Ma Y, Guo J, Wang Y. Self-microemulsifying drug delivery system for improving the bioavailability of water-insoluble drugs. J Nanopart Res. 2020; 22(1):1–4. doi:10.1007/s11051-019-4744-6

4. Gulsun T, Akdag Y, Izat N, Cetin M, Oner L, Sahin S. Development and characterization of orally disintegrating tablets containing metformin hydrochloride and glibenclamide. Pharmaceutical development technology. 2020;25(8):999–1009. doi:10.1080/10837450.2020.1772290

5. Singh AK, Chaurasiya A, Awasthi A, etc. The oral bioavailability of exemestane in the self-microemulsifying drug delivery system (SMEDDS) is enhanced. AAPS Pharmaceutical Technology. 2009;10(3):906-916. doi:10.1208/s12249-009-9281-7

6. Cheng C. The potential for expansion of biowaivers of BCS class III drugs with high solubility and low permeability: bridging evidence of metformin immediate-release tablets. Eur J Pharm Sci. 2004;22(4):297-304. doi:10.1016/s0928-0987(04)00095-8

7. Wakerly MG, Pouton CW, Meakin BJ, Morton FS. The effect of surfactant HLB on the self-emulsification efficiency of non-ionic surfactant-vegetable oil mixture. J Pharm Pharmacol. 1986;38(S12): 2P. doi:10.1111/j.2042-7158.1986.tb14231.x

8. Bolton CW. Lipid formulations for oral administration: non-emulsifying, self-emulsifying and "self-microemulsifying" drug delivery systems. Eur J Pharm Sci. 2000;11:S93–S98. doi:10.1016/s0928-0987(00)00167-6

9. Benita S, Lambert G, Garrigue JS. Self-emulsifying oral lipid formulations for improving the delivery of lipophilic drugs. Microencapsulation. 2005; 2: 429-480. doi:10.1201/9781420027990.pt3

10. Craig DQM, Lievens HSR, Pitt KG, Storey DE. Use low-frequency dielectric spectroscopy, surface tension measurement and particle size analysis to study the physical and chemical properties of the self-emulsifying system. Int J Pharm. 1993;96(1-3):147-155. doi:10.1016/0378-5173(93)90222-2

11. Barot B, Parejiya P, Patel T, Parikh R, Gohel M. Develop directly compressible metformin hydrochloride through spray drying technology. Acta Pharmaceutica Sinica. 2010;60(2):165–175. doi:10.2478/v10007-010-0016-9

12. Takasaki H, Yonemochi E, Ito M, Wada K, Terada K. The importance of binder moisture content in high-dose formulations of metformin hydrochloride prepared by wet aqueous granulation (MAG). Results Pharma Sci. 2015; 5:1-7. doi:10.1016/j.rinphs.2015.09.001

13. Block LC, Schmeling LO, Couto AG, etc. The effect of binder on wet granulation 500mg metformin hydrochloride tablets. Rev Cinc Farm Basica Apl. 2009;30(2):17-24.

14. Kelleher JF, Madi AM, Gilvary GC, etc. A fixed-dose compound preparation of metformin hydrochloride and sitagliptin phosphate prepared by melt granulation continuous processing technology. AAPS Pharmaceutical Technology. 2019;21(1):1-4. doi:10.1208/s12249-019-1553-2

15. Vaingankar P, Amin P. Continuous melt granulation to develop high drug-loaded metformin hydrochloride sustained-release tablets. Asia J Pharm Sci. 2017; 12(1): 37-50. doi:10.1016/j.ajps.2016.08.005

16. Wadher KJ, Kakde RB, Umekar MJ. The sustained-release metformin hydrochloride tablets were prepared by melt granulation technology using a combination of lipophilic waxes. Afr J Pharm Pharmacol. 2010; 4(8): 555–561.

17. Kim SH, Hwang KM, Cho CH, etc. Application of continuous twin-screw granulation in metformin hydrochloride sustained-release preparations Int J Pharm. 2017;529(1–2):410–422. doi:10.1016/j.ijpharm.2017.07.019

18. Aodah AH, Fayed MH, Alalaiwe A, Alsulays BB, Aldawsari MF, Khafagy ES. The in vitro/in vivo disintegration design, optimization and correlation of the new high-dose metformin hydrochloride rapid orally disintegrating tablet adopts the water-activated dry granulation process and quality design method. pharmaceutics. 2020; 12(7):598. doi:10.3390/pharmaceutics12070598

19. Tedstone A. Food Standards Agency. Nutritional food science. 2010; 40(3). doi:10.1108/nfs.2010.01740cab.004

20. Vang Spars II F, Krog N. Food emulsifier. Food science and technology. 2003.doi:10.1201/9780203913222.ch2

21. Hendy RJ, Butterworth KR, Gaunt IF, Kiss IS, Grasso P. Long-term toxicity study of sorbitol monostearate (Span 60) in mice. Food and cosmetics poisons. 1978;16(6):527–534. doi:10.1016/s0015-6264(78)80219-3

22. Katan MB, Grundy SM, Jones P, Law M, Miettinen T, Paoletti R. The efficacy and safety of plant stanols and sterols in controlling blood cholesterol levels. Mayo clinical procedures. 2003;78(8):965-978. doi:10.1016/s0025-6196(11)63144-3

23. Pardakhty A. Nonionic surfactant vesicles (Niosomes) as a new drug delivery system. Medical science. 2017; 154-184. doi:10.4018/978-1-5225-1762-7.ch007

24. Mady O. Span 60 as a microsphere matrix: preparation and in vitro characterization of novel ibuprofen-Span 60 microspheres. J Surfactant cleaner. 2016;20(1):219-232. doi:10.1007/s11743-016-1907-7

25. Ito A, Kleinebudde P. The effect of granulation temperature on particle size distribution in twin screw granulation (TSG). Pharmaceutical development technology. 2019;24(7):874–882. doi:10.1080/10837450.2019.1615089

26. Mady OY, Donia AA, Al-Shoubki AA, Qasim W. Enhance the paracellular pathway of metformin hydrochloride by molecular dispersion in 60 particles. Former pharmacist. 2019; 10. doi:10.3389/fphar.2019.00713

27. Yue Xu, Cui Yi, Yuan Tao, etc. The calcitriol tablet with mixed lipid solid dispersion has enhanced stability and content uniformity. Pharmaceutical development technology. 2020;25(7):899-907. doi:10.1080/10837450.2020.1760297

28. Saker A, Cares-Pacheco MG, Marchal P, Falk V. Evaluation of powder flowability in pellet compaction: How consistent is the Hausner ratio? Powder technology. 2019;354:52-63. doi:10.1016/j.powtec.2019.05.032

29. Behera BC, Sahoo SK, Dhal S, Barik BB, Gupta BK. Characterization of Glipizide-loaded Polymethacrylate Microspheres Prepared by Emulsion Solvent Evaporation Method. Trop J Pharm Res. 2008; 7(1): 879–885. doi:10.4314/tjpr.v7i1.14672

30. Mao S, Shi Y, Li L, Xu J, Schaper A, Kissel T. Process and formulation parameters on the properties and internals of poly(d,l-lactide-co-glycolide) microspheres formed by solvent evaporation The influence method of morphology. Eur J Pharm Biopharm. 2008;68(2):214-223. doi:10.1016/j.ejpb.2007.06.008

31. Oh TO, Kim JY, Ha JM, etc. The sublimation method is used to prepare highly porous gastric-retaining metformin tablets. Eur J Pharm Biopharm. 2013; 83(3): 460–467. doi:10.1016/j.ejpb.2012.11.009

32. Bretnall AE, Clark GS. Metformin hydrochloride. In: Overview of the Analysis of APIs and Excipients; 1998: 243-293. doi:10.1016/s0099-5428(08)60757-1

33. El-Gizawy SA, El-Maghraby GM, Hedaya AA. Formulation of acyclovir-loaded solid lipid nanoparticles: design, optimization and in vitro characterization. Pharmaceutical development technology. 2019;24(10):1287–1298. doi:10.1080/10837450.2019.1667385

34. Zancanella P, Oliveira DML, De Oliveira BH, etc. Mitotan liposomes for potential treatment of adrenocortical carcinoma: intestinal penetration in vitro and bioavailability in vivo. Pharmaceutical development technology. 2020; 25(8): 949–961. doi:10.1080/10837450.2020.1762645

35. Smith PL. In vitro methods for assessing intestinal permeability and metabolism. In: Models for Evaluating Drug Absorption and Metabolism; 1996:13-34. doi:10.1007/978-1-4899-1863-5_2

36. Jha SK, Karki R, Puttegowda VD, Harinarayana D. In vitro intestinal permeability study and pharmacokinetic evaluation of oral famotidine microemulsion. Notice of International School Resources. 2014; 2014: 1-7. doi:10.1155/2014/452051

37. Percie du Sert N, Ahluwalia A, Alam S, etc. Reporting animal studies: Explanation and clarification of ARRIVE Guide 2.0. Public Science Library Biology. 2020;18(7):e3000411. doi:10.1371/journal.pbio.3000411

38. Almoazen H. Chapter 4: Dosage Forms and Drug Delivery Systems. In: APhA Pharmacy Complete Review. 12th edition; 2017.doi:10.21019/9781582122816.ch4

39. Page DA, Dr. Carlson. A method to study the permeability of the rat intestine to carbon tetrachloride. Toxicological methods. 1991;1(3):188-198. doi:10.3109/15376519109044569

40. Friedrich M. Membrane transport in biology. In: Herausgegeben von GG, Tosteson DC, Using HH, editor. roll. 3. Transmission across multiple membrane systems. XVIII and 459 Seiten. 97 Abb., Form 26. Berlin, Heidelberg, New York: Springer-Verlag; 1980:202. roll. 24, No. 2. 1978. Preis: 148,- DM; USD 81,40. Food / Nahrung. doi: 10.1002/food.19800240214

41. Hemalatha S, Wahi A, Singh P, Chansoria JP. The hypoglycemic activity of Withania coagulans Dunal in streptozotocin-induced diabetic rats. J National Pharmaceutical Journal. 2004;93(2-3):261-264. doi:10.1016/j.jep.2004.03.043

42. Shanmugam S. Granulation technology and technology: the latest developments. Biological influence. 2017;5(1):55–63. doi:10.15171/bi.2015.04

43. Hamdan I, Farah D, Abu-Dahab RA-D. Chromatographic behavior and analytical method development of metformin hydrochloride: application in the study of Caco-2 cell permeation. Acta Pol Pharm. 2020;77(1):11-21. doi:10.32383/appdr/112237

44. Plata-Vargas E, De la Cruz-hernández C, Dorazco-González A, Fuentes-Noriega I, Morales-Morales D, Germán-Acacio JM. Melt synthesis of metformin succinate. Crystal structure, thermal, spectroscopy and solubility characteristics. J Mexican Society of Chemistry. 2017; 61(3). doi:10.29356/jmcs.v61i3.345

45. Ramukutty S, Jeyasudha R, Ramachandran E. Mechanical and thermal studies of metronidazole crystals. India J Phys. 2013;87(10):1001–1004. doi:10.1007/s12648-013-0337-x

46. ​​Mateer SW, Cardona J, Marks E, Goggin BJ, Hua S, Keely S. In vitro intestinal sacs were used to evaluate the mucosal permeability of gastrointestinal disease models. J Vis Exp. 2016; (108). doi:10.3791/53250

47. Subramanian N, Sharavanan SP, Chandrasekar P, Balakumar A, Moulik SP. Lassidipine self-emulsifying drug delivery system for improving oral bioavailability. Arch Pharm Res. 2015; 39(4): 481–491. doi:10.1007/s12272-015-0657-9

48. Madelima. The potential use of tight junction modulators to reversibly open membrane barriers and improve drug delivery. Journal of Biochim Biophys. 2009;1788(4):892-910. doi:10.1016/j.bbamem.2008.09.016

49. Dimitrijevic D, Shaw AJ, Florence AT. The effect of some nonionic surfactants on the transepithelial permeability of Caco-2 cells. J Pharm Pharmacol. 2000;52(2):157–162. doi:10.1211/0022357001773805

50. Proctor WR III. A new mechanism of intestinal absorption of the type II diabetes drug metformin: the role of cation-selective apical transporter in paracellular absorption; 2010.

51. Schon AJ. The clinical pharmacokinetics of metformin. Clinical pharmacokinetics. 1996;30(5):359-371. doi:10.2165/00003088-199630050-00003

52. Metzler CM. Drug statistics: practical and clinical applications. second edition. Via Sanford Bolton. Marcel Decker: New York. 1990. xvii 646pp. 16 × 23 cm. ISBN 0-8247-8267-4, US$99.75. J Pharm Sci. 1991;80(6):614. doi:10.1002/jps.2600800624

53. Al-Dossary BN. In vitro and in vivo availability of mebeverine hydrochloride suppositories. Scientific medicine. 2006;74(1):31-51. doi:10.3797/scipharm.2006.74.31

54. Support VRS. Regulatory views on the in vitro (dissolution)/in vivo (bioavailability) correlation. J Control release. 2001;72(1–3):127–132. doi:10.1016/s0168-3659(01)00268-1

This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and include the Creative Commons Attribution-Non-commercial (unported, v3.0) license. By accessing the work, you hereby accept the terms. The use of the work for non-commercial purposes is permitted without any further permission from Dove Medical Press Limited, provided that the work has an appropriate attribution. For permission to use this work for commercial purposes, please refer to paragraphs 4.2 and 5 of our terms.

Contact Us• Privacy Policy• Associations and Partners• Testimonials• Terms and Conditions• Recommend this site• Top

Contact Us• Privacy Policy

© Copyright 2021 • Dove Press Ltd • Software development of maffey.com • Web design of Adhesion

The views expressed in all articles published here are those of specific authors and do not necessarily reflect the views of Dove Medical Press Ltd or any of its employees.

Dove Medical Press is part of Taylor & Francis Group, the academic publishing department of Informa PLC. Copyright 2017 Informa PLC. all rights reserved. This website is owned and operated by Informa PLC ("Informa"), and its registered office address is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 3099067. UK VAT group: GB 365 4626 36

In order to provide our website visitors and registered users with services that suit their personal preferences, we use cookies to analyze visitor traffic and personalize content. You can understand our use of cookies by reading our privacy policy. We also retain data about visitors and registered users for internal purposes and to share information with our business partners. By reading our privacy policy, you can understand what data we retain, how we process it, who we share it with, and your right to delete data.

If you agree to our use of cookies and the content of our privacy policy, please click "Accept".