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Bioequivalence of a generic metformin tablet preparation

Yuen KH, Wong JW, Billa N, Julianto T, Toh WT

Int J Clin Pharmacol Ther, 1999 Jul;37(7):319-22.
PMID: 10442505

The bioavailability of a generic preparation of metformin (Diabetmin from Hovid Sdn Bhd) was evaluated in comparison with a proprietary product (Glucophage from Lipha Pharma Ltd., UK).

Matched MeSH terms: Metformin/pharmacokinetics*
Bioequivalence and pharmacokinetic comparison of two fixed dose combination of Metformin/ Glibenclamide formulations in healthy subjects under fed condition

Chang CT, Ang JY, Wong JM, Tan SS, Chin SK, Lim AB, et al.

Med J Malaysia, 2020 05;75(3):286-291.
PMID: 32467546

AIM: This study is conducted to compare the pharmacokinetic profiles of two fixed dose combination of metformin/glibenclamide tablets (500mg/5 mg per tablet).
MATERIALS AND METHODS: This is a single-center, single-dose, open-label, randomized, 2-treatment, 2-sequence and 2- period crossover study with a washout period of 7 days. All 28 adult male subjects were required to fast for at least 10 hours prior to drug administration and they were given access to water ad libitum during this period. Thirty minutes prior to dosing, all subjects were served with a standardized high-fat and high-calorie breakfast with a total calorie of 1000 kcal which was in accordance to the EMA Guideline on the Investigation of Bioequivalence. Subsequently, subjects were administered either the test or reference preparation with 240mL of plain water in the first trial period. During the second trial period, they received the alternate preparation. Plasma levels of glibenclamide and metformin were analysed separately using two different high performance liquid chromatography methods.
RESULTS: The 90% confidence interval (CI) for the ratio of the AUC0-t, AUC0-∞, and Cmax of the test preparation over those of the reference preparation were 0.9693-1.0739, 0.9598- 1.0561 and 0.9220 - 1.0642 respectively. Throughout the study period, no serious drug reaction was observed. However, a total of 26 adverse events (AE)/side effects were reported, including 24 that were definitely related to the study drugs, namely giddiness (n=17), while diarrheoa (n=3), headache (n=2) and excessive hunger (n=2) were less commonly reported by the subjects.
CONCLUSION: It can be concluded that the test preparation is bioequivalent to the reference preparation.

Matched MeSH terms: Metformin/pharmacokinetics*
Simple high-performance liquid chromatographic method for the determination of metformin in human plasma

Kah Hay Yuen, Kok Khiang Peh

J Chromatogr B Biomed Sci Appl, 1998 Jun 12;710(1-2):243-6.
PMID: 9686895

A simple high-performance liquid chromatographic method using ultraviolet detection was developed for the determination of metformin in human plasma. The method entailed direct injection of the plasma sample after deproteination using perchloric acid. The mobile phase comprised 0.01 M potassium dihydrogen orthophosphate (pH 3.5) and acetonitrile (60:40, v/v). Analyses were run at a flow-rate of 1.0 ml/min with the detector operating at a detection wavelength of 234 nm. The method is specific and sensitive, with a quantification limit of approximately 60 ng/ml and a detection limit of 15 ng/ml at a signal-to-noise ratio of 3:1. The mean absolute recovery value was about 97%, while the within-day and between-day coefficient of variation and percent error values of the assay method were all less than 8%. The calibration curve was linear over a concentration range of 62.5-4000 ng/ml.

Matched MeSH terms: Metformin/pharmacokinetics
Relating in vitro/in vivo data of two controlled-release metformin formulations

Yuen KH, Peh KK, Tan BL

Drug Dev Ind Pharm, 1999 May;25(5):613-8.
PMID: 10219530

This study was conducted to compare the bioavailability of two controlled-release metformin preparations (Diabetmin Retard and Glucophage Retard) and also to correlate the in vitro and in vivo data obtained with the two preparations. Twelve healthy volunteers participated in the study, conducted according to a completely randomized, two-way crossover design. The preparations were compared using area under the plasma concentration-time curve AUC0-infinity, time to reach peak plasma concentration Tmax, and peak plasma concentration Cmax, while correlation was determined between in vitro release and in vivo absorption. Diabetmin Retard demonstrated a slower rate of in vitro release, but a faster rate of in vivo absorption than Glucophage Retard. However, the in vivo absorption of both products was found to be slower than that of drug released in vitro. A satisfactory relationship could be established between the in vitro and in vivo results, but there was no rank order correlation. No statistically significant difference was observed between the two preparations in the parameters AUC0-infinity and Cmax. However, a slight but statistically significant difference was observed between the Tmax values, but it may not be therapeutically significant. Moreover, the 90% confidence interval for the ratio of the logarithmic transformed AUC0-infinity values, as well as the logarithmic transformed Cmax values, of Diabetmin Retard over those of Glucophage Retard was within the acceptance criteria of 0.80-1.25.

Matched MeSH terms: Metformin/pharmacokinetics
Fulltext Gamma scintigraphic evaluation of floating gastroretentive tablets of metformin HCl using a combination of three natural polymers in rabbits

Razavi M, Karimian H, Yeong CH, Chung LY, Nyamathulla S, Noordin MI

Drug Des Devel Ther, 2015;9:4373-86.
PMID: 26273196 DOI: 10.2147/DDDT.S86263

The present research was aimed at formulating a metformin HCl sustained-release formulation from a combination of polymers, using the wet granulation technique. A total of 16 formulations (F1-F16) were produced using different combinations of the gel-forming polymers: tamarind kernel powder, salep (palmate tubers of Orchis morio), and xanthan. Post-compression studies showed that there were no interactions between the active drug and the polymers. Results of in vitro drug-release studies indicated that the F10 formulation which contained 5 mg of tamarind kernel powder, 33.33 mg of xanthan, and 61.67 mg of salep could sustain a 95% release in 12 hours. The results also showed that F2 had a 55% similarity factor with the commercial formulation (C-ER), and the release kinetics were explained with zero order and Higuchi models. The in vivo study was performed in New Zealand White rabbits by gamma scintigraphy; the F10 formulation was radiolabeled using samarium (III) oxide ((153)Sm2O3) to trace transit of the tablets in the gastrointestinal tract. The in vivo data supported the retention of F10 formulation in the gastric region for 12 hours. In conclusion, the use of a combination of polymers in this study helped to develop an optimal gastroretentive drug-delivery system with improved bioavailability, swelling, and floating characteristics.

Matched MeSH terms: Metformin/pharmacokinetics
Fulltext Gastroretentive behavior of orally administered radiolabeled tamarind seed formulations in rabbits validated by gamma scintigraphy

Razavi M, Karimian H, Yeong CH, Fadaeinasab M, Khaing SL, Chung LY, et al.

Drug Des Devel Ther, 2017;11:1-15.
PMID: 28031701 DOI: 10.2147/DDDT.S115466

This study aimed to formulate floating gastroretentive tablets containing metformin hydrochloric acid (HCl), using various grades of hydrogel such as tamarind powders and xanthan to overcome short gastric residence time of the conventional dosage forms. Different concentrations of the hydrogels were tested to determine the formulation that could provide a sustained release of 12 h. Eleven formulations with different ratios of tamarind seed powder/tamarind kernel powder (TKP):xanthan were prepared. The physical parameters were observed, and in vitro drug-release studies of the prepared formulations were carried out. Optimal formulation was assessed for physicochemical properties, thermal stability, and chemical interaction followed by in vivo gamma scintigraphy study. MKP3 formulation with a TKP:xanthan ratio of 3:2 was found to have 99.87% release over 12 h. Furthermore, in vivo gamma scintigraphy study was carried out for the optimized formulation in healthy New Zealand White rabbits, and the pharmacokinetic parameters of developed formulations were obtained. 153Sm2O3 was used to trace the profile of release in the gastrointestinal tract of the rabbits, and the drug release was analyzed. The time (Tmax) at which the maximum concentration of metformin HCl in the blood (Cmax) was observed, and it was extended four times for the gastroretentive formulation in comparison with the formulation without polymers. Cmax and the half-life were found to be within an acceptable range. It is therefore concluded that MKP3 is the optimal formulation for sustained release of metformin HCl over a period of 12 h as a result of its floating properties in the gastric region.

Matched MeSH terms: Metformin/pharmacokinetics
Population pharmacokinetics of metformin in healthy subjects and patients with type 2 diabetes mellitus: simulation of doses according to renal function

Duong JK, Kumar SS, Kirkpatrick CM, Greenup LC, Arora M, Lee TC, et al.

Clin Pharmacokinet, 2013 May;52(5):373-84.
PMID: 23475568 DOI: 10.1007/s40262-013-0046-9

Metformin is contraindicated in patients with renal impairment; however, there is poor adherence to current dosing guidelines. In addition, the pharmacokinetics of metformin in patients with significant renal impairment are not well described. The aims of this study were to investigate factors influencing the pharmacokinetic variability, including variant transporters, between healthy subjects and patients with type 2 diabetes mellitus (T2DM) and to simulate doses of metformin at varying stages of renal function.

Matched MeSH terms: Metformin/pharmacokinetics*
Fulltext Gamma scintigraphic study of the hydrodynamically balanced matrix tablets of Metformin HCl in rabbits

Razavi M, Karimian H, Yeong CH, Sarji SA, Chung LY, Nyamathulla S, et al.

Drug Des Devel Ther, 2015;9:3125-39.
PMID: 26124637 DOI: 10.2147/DDDT.S82935

The purpose of this study is to evaluate the in vitro and in vivo performance of gastro-retentive matrix tablets having Metformin HCl as model drug and combination of natural polymers. A total of 16 formulations were prepared by a wet granulation method using xanthan, tamarind seed powder, tamarind kernel powder and salep as the gel-forming agents and sodium bicarbonate as a gas-forming agent. All the formulations were evaluated for compendial and non-compendial tests and in vitro study was carried out on a USP-II dissolution apparatus at a paddle speed of 50 rpm. MOX2 formulation, composed of salep and xanthan in the ratio of 4:1 with 96.9% release, was considered as the optimum formulation with more than 90% release in 12 hours and short floating lag time. In vivo study was carried out using gamma scintigraphy in New Zealand White rabbits, optimized formulation was incorporated with 10 mg of (153)Sm for labeling MOX2 formulation. The radioactive samarium oxide was used as the marker to trace transit of the tablets in the gastrointestinal tract. The in vivo data also supported retention of MOX2 formulation in the gastric region for 12 hours and were different from the control formulation without a gas and gel forming agent. It was concluded that the prepared floating gastro-retentive matrix tablets had a sustained-release effect in vitro and in vivo, gamma scintigraphy played an important role in locating the oral transit and the drug-release pattern.

Matched MeSH terms: Metformin/pharmacokinetics*