Formulation and Evaluation of Metformin Tablets

 Corresponding author: Padwal Prachi Nandkumar. Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution License 4.0. Formulation and Evaluation of Metformin Tablets Padwal Prachi Nandkumar 1, *, Padwal Payal Hemant 2, Modhave Rutuja Satish 2, Pathan Mujeba Rajjak 2, Khore Akanksha Dattatray 2 and Londhe Reema Chandrkant 1 1 Assistant Professor, Department of Quality Assurance Technique, Samarth Institute of Pharmacy, Belhe,Pune, Maharashtra. 2 Student of Samarth Institute of Pharmacy, Belhe, Pune, Maharashtra. World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 049-053 Publication history: Received on 21 September 2025; revised on 01 November 2025; accepted on 03 November 2025 Article DOI: https://doi.org/10.30574/wjbphs.2025.24.2.0944 Abstract Metformin hydrochloride is an oral hypoglycemic drug that enhances glucose tolerance in type 2 diabetes patients & lowers basal plasma glucose levels. The purpose of the study was to formulate and optimize MET matrix tablets for SR use. The SR matrix tablet of MET was prepared by wet granulation technique using Polyvinyl pyrrolidone K30 and hydroxyl propyl methylcellulose of different viscosity grades. The influence of varying the polymer ratios was evaluated. The excipients used in this study did not modify physicochemical properties of the drug. MET has relatively short plasma half-life, low absolute bioavailability. The need for the administration 2 to 3 times a day when larger doses are required can reduce patient satisfaction.SR formulation which would sustain plasma level for 8-12 h may be adequate for once daily dosing of MET.SR formulations are required for MET to extend its action duration and to enhance patient compliances. The formulation of oral sustained release systems has been a challenge to formulation scientists because of the failure of such systems to restrain and localize the system in the desired sites of the gastrointestinal tract. Out of all the formulation trial batches, F3 formulation reveals optimum results. It has been noted that HPMC K100M is incapable of providing good drug release profile but the combination of HPMC K100M and Polyvinyl pyrrolidone K30 in combination provide the best drug release kinetics. So, controlled release matrix tablets of metformin hydrochloride can be anticipated to minimize the administration frequency and reduce dose dependent side effects. Keywords: Metformin Hydrochloride; SR Matrix Tablet; HPMC K100M; Wet Granulation Technique 1. Introduction Sustained-release (SR) oral delivery systems are intended to attain therapeutically effective concentrations of drug in systemic circulation over an extended period of time1 towards novel drug delivery of pharmaceutical technology; SR matrix tablets have given a new development2. Reservoir type of dosage forms designed to release drug constantly and continuously over satisfactory prolonged period of time to maintain plasma drugs concentration within therapeutic level3. Drug products that are formulated to minimize dosing by altering the rate of drug absorption have been there for many years. Of all the dosage forms, matrix tablets are commonly used in oral sustained release (SR) because they are easy and simple to formulate. Matrix system refers to release system, which extends and regulates the release of drug dissolved or dispersed. Indeed, matrix is a good complex of one or more drugs along with a gelling agent i.e. hydrophilic polymer4-6. It is estimated that by 2025 around 300 million people will be diagnosed with diabetes7, 8. World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 049-053 50 Metformin hydrochloride (MET) is an oral anti-hyperglycemic medication employed in the management of Type 2 diabetes in patients who are not able to control the disease with diet alone and exercise9. Unlike Insulin and Sulfonylurea, MET does not lead to weight gain; hence it emerges as the first choice for therapy of type 2 diabetes and is even administered in obese individuals with type 1 diabetes to counteract insulinesistance10. Chemically, MET is (N, N-dimethyl iridoid carbonatite diamide hydrochloride) falls under the category of biguanides, hydrophilic, BCS classIII drug11, 12. It enhances glucose tolerance by reducing basal and postprandial glucose by reducing intestinal absorption of glucose, reducing hepatic gluconeogenesis, enhancing glycogenesis, lipogenesis and glucose uptake by adipocytes and muscle cells9, 13. MET is a very water soluble medication (0.5 g/ml)given up to2.5 g/day in three different doses given with food to reduce potential gastrointestinal side effects like anorexia, abdominal pain, nausea and diarrhea14. Figure 1 Overview of Human Metabolism 2. Materials and methods Metformin HCl was obtained as a gift sample from Arbor Pharmaceuticals Ltd, New Delhi (India). Hydroxy propyl methyl cellulose, polyvinyl pyrrolidone K30, magnesium stearate was procured from HI media Chem. Lab, Mumbai. Talc and sodium alginate, starch was bought from Loba Chemicals Pvt. Ltd. Mumbai. Acetonitrile, methanol and Isopropyl alcohol were HPLC grade available from Merck Ltd., India. All the other reagents used were of analytical grade. Triple distilled water was produced in house. 2.1. Reformulation studies 2.1.1. Physical characteristics By visual examination, the drug was identified for physical characters like colour, texture, odour etc. 2.1.2. Solubility Solubility of the drug was determined by taking some quantity of drug (about 10 mg) in the 10 ml volumetric flasks separately and added the 10 ml of the solvent (water, ethanol, methanol, 0.1N HCL, 0.1N NaOH, chloroform and 7.4 pH buffer) Shake vigorously and kept for some time. Note the solubility of the drug in various solvents (at room temperature). World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 049-053 51 2.1.3. Melting point A small quantity of powder was placed into a fusion tube. That tube was placed in the melting point determining apparatus (Hemline) containing castor oil. The temperature of the castor oil was gradual increased automatically and read the temperature at which powder started to melt and the temperature when all the powder gets melted. 2.1.4. FTIR spectroscopy The sample in KBr should be between 0.2% and 1 %. The pellet is much thicker than a liquid film, thus a reduction concentration in the sample is needed (Beer's Law). For the die set which you will be using, approximately 80 mg of the mixture is desired. Too high of an attention creates issues that usually have clean pellets. FTIR spectra of the samples were obtained between a spectral range from 4700 to 400 cm-1 with 20 scans and 4 cm-1 resolution. 2.1.5. Determination of λ max of MET MET, 100 mg was accurately weighted into a 100 ml volumetric flask, dissolved in distilled water and the volume was made up with distilled water. Pipette 1 ml of this solution. 3. Micromeritics properties 3.1. Angle of repose The fixed funnel and free-standing cone methods employ a funnel that is secured with its tip at a given height, h, which was kept 2cm above graph paper that is placed on a flat horizontal surface. Angle of repose can be determined by following equation θ = tan-1 (h/r) Where, θ is the angle of repose, his height of pile; r is radius of base of the pile. 3.2. Bulk density (BD) An accurately weighed powder blend from each formula was lightly shaken to break any agglomerates formed and it was introduced in to a measuring cylinder. The volume occupied by the powder was measured which gave bulk volume. The BD of powder blends was determined using the following formula. 3.3. Bulk density = Total weight of powder/Total volume of powder 3.3.1. Tapped bulk density (TBD) An exactly weighed powder mixture from each formula was gently shaken to destroy any agglomerates developed and it was placed in a measuring cylinder. The measuring cylinder was tapped until no further change in volume was observed • which provided the tapped volume. The TBD of powder blends was • calculated by the following formula. • TBD = Total weight of powder/Total volume of tapped Powder. Table 1 Formulation Ingredients Ingredient Quantity in mg Quantity required Metformin HCL 500 100 PVP K30 50 10 Lactose monohydrate 12.5 2.5 MCC 72.5 14.5 Magnesium Sterate 7.5 1.5 Talc 7.5 1 .5 Total 650 130 World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 049-053 52 4. Results Melting point of MET (pure drug) was determined to be 223-226°C. MET was soluble freely in water, sparingly soluble in methanol and ethanol and insoluble in Acetone. Identification of MET was carried out by FTIR spectroscopy in reference to marker compound. It was found from the outcome of IR spectrum according to specification Figure 1. MET was found to have a linear calibration curve in a concentration range of 2-12 µg/ml at 234nm Figure. 2. Angle of repose was found by funnel method. Tapped density and bulk density were measured by cylinder method, and carr's index (CI) was calculated using the following equation. Carr's index = (TBD-LBD) ×100/TBD. Hausner's ratio was indicative of inter particle friction and could be applied to predict powder flow properties. Hausner's value of the prepared granules ranged from 1.15 to 1.16 was thought to indicate good flow properties Table 2. The physical appearance, tablet hardness, friability, weight variation anddrug content uniformity of all tablet formulations was found to be satisfactory and reproducible as observed from the data in Table. 3. Tablet hardness was good (6 to 8 kg/cm2) varying with other compression force applied, and friability was less than 0.5% (wt/wt). The manufactured tablets showed low weight variation and a high degree of drug content uniformity, indicating that wet granulation is an acceptable method for preparing goodquality matrix tablets of metformin HCl. First, the tablets were made with HPMC K4M (F1) which released 40.61% and 81.23% of metformin HCl in 1 and 4 h respectively. And the tablets prepared with HPMC K15M (F2) exhibits 81.01% drug released in 4 h. Tablets formulated with K100M (F3), drug-to-polymer ratios 5: 2 and isopropyl alcohol as granulating agent slow the release of metformin HCl 36.11%, 73.65% and 93.44 at 1h, 4 h and 8 h respectively. F3 formulation has demonstrated an ideal formulation because of its closest profile to the target in release terms. Table 2 Result of pre-compression properties of MET SR tablets Formulation LED TBD Angel of Repose Carr's Index Hausner's Ratio F1 0.307 0.357 25.94+0.56 13.84 1.15 F2 0.266 0.312 26.32+0.87 14.66 1.16 F3 0.384 0.441 25.98+0.40 13.46 1.15 Table 3 Results of post compression properties of MET SR tablets F. Code Hardness Thickness Weight Variation Friability % Assay% F1 6-7 6.48 760 0.1 96.74 F2 7-8 6.52 760 0.1 99.4 F3 6-7 6.51 780 0.1 99.5 5. Conclusion In our study, to reach an intended target release profile, SR formulation of metformin HCl tablets were developed with polymer substance such as HPMC K100M. It has been reported that excipient like HPMC K100M with polyvinyl pyrrolidone can be employed with wet granulation process. The use has produced comparable findings with other works in the literature in SR formulation preparation. But in developing SR formulations with metformin HCl, it was found that HPMC K100M gives an improved result in preparation of SR formulation prepared by wet granulation method. World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 049-053 53 Compliance with ethical standards Acknowledgments We sincerely acknowledge the continuous guidance, motivation, and constructive feedback provided by our mentor, [Dr./Prof. Prachi Padwal]. Their expertise and patience have been instrumental in shaping this review paper. 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