BACKGROUND AND OBJECTIVES

The in vitro bioequivalence assessment using a dissolution apparatus, as specified by the United States Pharmacopeia (USP), is a critical parameter in the formulation and development of generic pharmaceutical products. This study is crucial for evaluating the interchangeability of generic drugs with their reference innovator counterparts. Post-market surveillance of generic drugs ensures consistent quality after distribution in the market. Metformin hydrochloride, a widely prescribed oral hypoglycemic agent for managing type 2 diabetes, is among the most utilized medications globally.

In the Philippines, there is a growing need to assess the bioequivalence of various generic formulations of metformin HCl f ilm coated tablets to ensure compliance with regulatory requirements. The Philippine Food and Drug Administration (FDA) mandates in vivo or in vitro bioequivalence including, dissolution profile comparison, as a prerequisite for the registration of generic drugs. This study aims to evaluate the quality and in vitro bioequivalence of metformin HCl f ilm-coated tablets available in the Philippine market by comparing their dissolution profiles against the innovator, Glucophage. This research seeks to provide insights into the interchangeability, therapeutic equivalence, and overall quality of these generic formulations, thus contributing to public health and regulatory standards.

Generic metformin HCl film-coated tablets were subjected to quality control tests, including weight variation, thickness and diameter, hardness, friability, and disintegration tests, in accordance with USP guidelines. To assess in vitro bioequivalence, dissolution testing was performed, and the concentration of the dissolved drug was determined using a microplate assay reader to measure absorbance. Dissolution profiles of the generic metformin HCl film-coated tablets were compared to that of the innovator drug, Glucophage to evaluate bioequivalence.

All tested generic metformin HCl film-coated tablets complied with USP specifications for quality control tests, except for the hardness test, where three brands failed to meet the required standards. While for dissolution testing, five out of six generic brands demonstrated acceptable dissolution profiles and were bioequivalent to the innovator drug Glucophage. However, one brand (Brand A) failed to meet the bioequivalence criteria, exhibiting a dissolution profile outside the acceptable limits.

This study demonstrates that most generic metformin HCl film-coated tablets available in the Philippine market meet the United States Pharmacopeia (USP) quality control requirements and exhibit in vitro bioequivalence with the innovator drug. However, the failure of three brands to meet the hardness specifications and the lack of bioequivalence in one brand highlight the need for stringent quality assurance and  regulatory oversight. Ensuring compliance with these standards is critical to maintaining the safety, efficacy, and therapeutic interchangeability of generic drugs. These findings emphasize the importance of continuous post-market surveillance to uphold the quality of generic medications in the market, to safeguard public health.

BACKGROUND: Alpha-glucosidase inhibitors or dipeptidyl peptidase-4 inhibitors are both hypoglycemia agents that specifically impact on postprandial hyperglycemia. We compared the effects of acarbose and sitagliptin add on to metformin on time in range (TIR) and glycemic variability (GV) in Chinese patients with type 2 diabetes mellitus through continuous glucose monitoring (CGM). METHODS: This study was a randomized, open-label, active-con-trolled, parallel-group trial conducted at 15 centers in China from January 2020 to August 2022. We recruited patients with type 2 diabetes aged 18-65 years with body mass index (BMI) within 19-40 kg/m 2 and hemoglobin A1c (HbA1c) between 6.5% and 9.0%. Eligible patients were randomized to receive either metformin combined with acarbose 100 mg three times daily or metformin combined with sitagliptin 100 mg once daily for 28 days. After the first 14-day treatment period, patients wore CGM and entered another 14-day treatment period. The primary outcome was the level of TIR after treatment between groups. We also performed time series decomposition, dimensionality reduction, and clustering using the CGM data. RESULTS: A total of 701 participants received either acarbose or sitagliptin treatment in combination with metformin. There was no statistically significant difference in TIR between the two groups. Time below range (TBR) and coefficient of variation (CV) levels in acarbose users were significantly lower than those in sitagliptin users. Median (25th percentile, 75th percentile) of TBR below target level <3.9 mmol/L (TBR 3.9 ): Acarbose: 0.45% (0, 2.13%) vs . Sitagliptin: 0.78% (0, 3.12%), P = 0.042; Median (25th percentile, 75th percentile) of TBR below target level <3.0 mmol/L (TBR 3.0 ): Acarbose: 0 (0, 0.22%) vs . Sitagliptin: 0 (0, 0.63%), P = 0.033; CV: Acarbose: 22.44 ± 5.08% vs . Sitagliptin: 23.96 ± 5.19%, P <0.001. By using time series analysis and clustering, we distinguished three groups of patients with representative metabolism characteristics, especially in GV (group with small wave, moderate wave and big wave). No significant difference was found in the complexity of glucose time series index (CGI) between acarbose users and sitagliptin users. By using time series analysis and clustering, we distinguished three groups of patients with representative metabolism characteristics, especially in GV. CONCLUSIONS: Acarbose had slight advantages over sitagliptin in improving GV and reducing the risk of hypoglycemia. Time series analysis of CGM data may predict GV and the risk of hypoglycemia. TRIAL REGISTRATION Chinese Clinical Trial Registry: ChiCTR2000039424.
Humans ; Metformin/therapeutic use* ; Sitagliptin Phosphate/therapeutic use* ; Acarbose/therapeutic use* ; Diabetes Mellitus, Type 2/blood* ; Middle Aged ; Male ; Female ; Adult ; Blood Glucose/drug effects* ; Hypoglycemic Agents/therapeutic use* ; Aged ; Glycated Hemoglobin/metabolism* ; Adolescent ; Young Adult ; China ; East Asian People

Objective To study the impacts of curcumin on the proliferation, migration and cisplatin (DDP) resistance of bladder cancer cells by regulating the liver kinase B1-AMP activated protein kinase-microtubule-associated protein 1 light chain 3 (LKB1-AMPK-LC3) signaling pathway. Methods Human bladder cancer cell line T24 was cultured in vitro, and its DDP resistant T24/DDP cells were induced by cisplatin (DDP). After treating T24 and T24/DDP cells with different concentrations of curcumin, the optimal concentration of curcumin was screened by MTT assay. T24 cells were randomly grouped into control group, curcumin group, metformin group, and combination group of curcumin and metformin. After treatment with curcumin and LKB1-AMPK activator metformin, the proliferation, autophagy, migration, and apoptosis of T24 cells in each group were detected by MTT assay, monodansylcadavrine (MDC) fluorescence staining, cell scratch assay, and flow cytometry, respectively. Western blot was used to detect the expression of proteins related to LKB1-AMPK-LC3 signaling pathway in T24 cells of each group. T24/DDP cells were randomly assigned into control group, curcumin group, metformin group, and combination group of curcumin and metformin. Cells were treated with curcumin and metformin according to grouping and treated with different concentrations of DDP simultaneously. Then, the effect of curcumin on the DDP resistance coefficient of T24/DDP cells was detected by MTT assay. T24/DDP cells were randomly grouped into control group, DDP group, combination groups of DDP and curcumin, DDP and metformin, DDP, curcumin and metformi. After treatment with DDP, curcumin, and metformin, the proliferation, autophagy, migration, apoptosis, drug resistance, and the expression of proteins related to LKB1-AMPK-LC3 signaling pathway in T24/DDP cells of each group were detected with the same methods. Results Compared with the control group, the activity of T24 cells, relative number of autophagosomes, migration rate, Phosphorylated-LKB1 (p-LKB1)/LKB1, Phosphorylated-AMPK (p-AMPK)/AMPK, LC3II/LC3I, and the DDP resistance coefficient of T24/DDP cells in the curcumin group were lower, and the apoptosis rate of T24 cells was higher; the changes in various indicators in the metformin group were opposite to those in the curcumin group. Compared with the curcumin group, the activity of T24 cells, relative number of autophagosomes, migration rate, p-LKB1/LKB1, p-AMPK/AMPK, LC3II/LC3I, and the DDP resistance coefficient of T24/DDP cells in the combination group of curcumin and metformin were higher, and the apoptosis rate of T24 cells was lower. Compared with the control group, there were no obvious changes in various indicators of T24/DDP cells in the DDP group. Compared with the control group and DDP group, the viability of T24/DDP cells, relative number of autophagosomes, migration rate, P-glycoprotein (P-gp) protein expression, p-LKB1/LKB1, p-AMPK/AMPK, and LC3II/LC3I in the combination group of DDP and curcumin were lower, and the apoptosis rate of T24/DDP cells was higher; the changes in the above indicators in the combination group of DDP and metformin were opposite to those in the combination group of DDP and curcumin. Compared with the combination group of DDP and curcumin, the viability of T24/DDP cells, relative number of autophagosomes, migration rate, P-gp protein expression, p-LKB1/LKB1, p-AMPK/AMPK, and LC3II/LC3I in the combination group of DDP, curcumin and metformin were higher, and the apoptosis rate of T24/DDP cells was lower. Conclusion Curcumin can reduce the activity of LKB1-AMPK-LC3 signaling pathway, thereby inhibiting autophagy, proliferation and migration of bladder cancer cells, promoting their apoptosis, and weakening their resistance to DDP.
Humans ; Cisplatin/pharmacology* ; Curcumin/pharmacology* ; Cell Proliferation/drug effects* ; Signal Transduction/drug effects* ; Protein Serine-Threonine Kinases/genetics* ; AMP-Activated Protein Kinases/metabolism* ; Drug Resistance, Neoplasm/drug effects* ; Urinary Bladder Neoplasms/pathology* ; Cell Line, Tumor ; Cell Movement/drug effects* ; AMP-Activated Protein Kinase Kinases ; Microtubule-Associated Proteins/metabolism* ; Apoptosis/drug effects* ; Antineoplastic Agents/pharmacology* ; Metformin/pharmacology* ; Autophagy/drug effects*

OBJECTIVES: Recent evidence suggests that the gut may be a primary site of metformin action. However, studies on the effects of metformin on gut microbiota remain limited, and its impact on gut microbial metabolites such as short-/medium-chain fatty acids is unclear. This study aims to investigate the effects of metformin on gut microbiota, short-/medium-chain fatty acids, and associated metabolic benefits in high-fat diet rats. METHODS: Twenty-four Sprague-Dawley rats were randomly divided into 3 groups: 1) Normal diet group (ND group), fed standard chow; 2) high-fat diet group (HFD group), fed a high-fat diet; 3) high-fat diet + metformin treatment group (HFD+Met group), fed a high-fat diet for 8 weeks, followed by daily intragastric administration of metformin solution (150 mg/kg body weight) starting in week 9. At the end of the experiment, all rats were sacrificed, and serum, liver, and colonic contents were collected for assessment of glucose and lipid metabolism, liver pathology, gut microbiota composition, and the concentrations of short-/medium-chain fatty acids. RESULTS: Metformin significantly improved HFD-induced glucose and lipid metabolic disorders and liver injury. Compared with the HFD group, the HFD+Met group showed reduced abundance of Blautia, Romboutsia, Bilophila, and Bacteroides, while Lactobacillus abundance significantly increased (all P<0.05). Colonic contents of butyric acid, 2-methyl butyric acid, valeric acid, octanoic acid, and lauric acid were significantly elevated (all P<0.05), whereas acetic acid, isoheptanoic acid, and nonanoic acid levels were significantly decreased (all P<0.05). Spearman correlation analysis revealed that Lactobacillus abundance was negatively correlated with body weight gain and insulin resistance, while butyrate and valerate levels were negatively correlated with insulin resistance and liver injury (all P<0.05). CONCLUSIONS Metformin significantly increases the abundance of beneficial bacteria such as Lactobacillus and promotes the production of short-/medium-chain fatty acids including butyric, valeric, and lauric acid in the colonic contents of HFD rats, suggesting that metformin may regulate host metabolism through modulation of the gut microbiota.
Animals ; Metformin/pharmacology* ; Rats, Sprague-Dawley ; Diet, High-Fat/adverse effects* ; Rats ; Gastrointestinal Microbiome/drug effects* ; Male ; Fatty Acids, Volatile/metabolism* ; Fatty Acids/metabolism*

Background: Metformin has been studied for its anti-proliferative effects on endometrial cells, and it is hypothesized to have a synergistic effect with progestin therapy in suppressing endometrial cell proliferation. This systematic review and meta-analysis aimed to determine the efficacy of adjunctive metformin in the clinical regression of endometrial hyperplasia and early-stage endometrial carcinoma. Methodology: This meta-analysis followed the Cochrane methodology and adhered to the PRISMA 2020 guidelines. Randomized controlled trials (RCTs) were included if they enrolled reproductive-aged women with endometrial hyperplasia (with and without atypia) and endometrial carcinoma who were treated with progestin and metformin. The primary outcome was the complete response rate at 12-16 weeks, and secondary outcomes included relapse rate, clinical pregnancy rate, and live birth rate. Odds ratios (ORs) and 95% confidence intervals (CIs) were used for dichotomous data. Results: Six RCTs were included. The addition of metformin to progestin therapy may increase the complete response rate of endometrial hyperplasia without atypia (OR 5.12, 95% CI 1.17 to 22.41; n=102) and live birth rates (OR 2.51, 95% CI 1.34 to 4.69; n=188) compared to progestin therapy alone, but the certainty of the evidence is low. Metformin did not have a significant effect on the clinical response of endometrial hyperplasia with atypia and endometrial carcinoma, relapse rates, and clinical pregnancy rates. Conclusion Current evidence is uncertain on the potential benefit of metformin with progestin in endometrial hyperplasia and carcinoma. Future high-quality randomized controlled trials with larger sample sizes and longer follow-up periods are needed to support practice recommendations.
Endometrial Hyperplasia ; Endometrial Neoplasms ; Metformin ; Progesterone

Objective: To determine the efficacy of metformin and insulin in the management of gestational diabetes mellitus (GDM). Methodology: Randomized controlled trials (RCT) were retrieved from the databases. All references cited in the articles were also searched by hand to identify additional publications. Studies included were limited to trials on metformin and insulin in the management of GDM in singleton pregnancies. Four RCTs were analyzed in the study. The risk of bias was assessed using Preferred Reporting Items for Systematic reviews and Meta-Analyses Cochrane Collaboration’s tool (Rob 2). Random effects meta-analysis was carried out to pool the data. All analyses were conducted in Review Manager 5.3.5 (2014). Results: Meta-analysis of four RCT involving 807 participants (405 were treated with metformin and 402 were treated with insulin) shows that there was no significant difference between metformin and insulin in achieving glycemic control as to fasting blood sugar (FBS), postprandial blood glucose (PPBG), and glycosylated hemoglobin, mean difference (MD) −0.43 (95% confidence interval [CI] −2.77–1.91; P = 0.72), MD −2.13 (95% CI −5.16–0.90, P = 0.17), MD −0.09 (95% CI −0.20–0.02, P = 0.10), respectively. For maternal outcomes, there was a statistically significant 69% decreased risk of hypoglycemia in the metformin group (risk ratio [RR] 0.31, 95% CI 0.20–0.49; P < 0.001). There was no difference in terms of risk of preterm birth (RR 1.11, 95% CI 0.75–1.64, P = 0.60); hypertensive disorders (RR 1.06, 95% CI 0.71–1.60, P = 0.77); polyhydramnios (RR 1.04, 95% CI 0.51–2.14, P = 0.91); and risk of cesarean delivery (RR 0.90, 95% CI 0.75–1.08, P = 0.27). For neonatal outcomes, there was statistically significant 34% reduction on the risk of neonatal hypoglycemia (RR 0.66, 95% CI 0.46–0.94; P = 0.02) in the metformin group. There was no statistical difference in terms of mean birthweight (MD − 81.34, 95% CI −181.69–19.02, P = 0.11). Metformin has decreased the risk of newborns weighing more than 4000 g, babies with birthweight >90th percentile by 27% (RR 0.73, 95% CI 0.28–1.90, P = 0.52), and 20% (RR 0.80, 95% CI 0.54–1.18,P = 0.26), respectively, but these were not statistically significant. There was no significant difference in terms of risk of birthweight <10th percentile (RR 1.17, 95% CI 0.60–2.31, P = 0.65); APGAR <7 (RR 1.17, 95% CI 0.65–2.08, P = 0.60), birth trauma (RR 0.77, 95% CI 0.23–2.58, P = 0.67), and jaundice requiring phototherapy RR 1.04, 95% CI 0.66–1.65, P = 0.85). Neonatal intensive care unit admission (RR 0.89, 95% CI 0.64–1.23, P = 0.48), respiratory distress syndrome (RR 0.73, 95% CI 0.36–1.50, P = 0.39), transient tachypnea (RR 0.78, 95% CI 0.27–2.19, P = 0.63), and any congenital anomaly (RR 0.58, 95% CI 0.20–1.67, P = 0.31) were decreased in the metformin group but was not statistically significant. Conclusion There was no significant difference between metformin and insulin in achieving glycemic control as to FBS and PPBG among patients with GDM. There was a statistically significant reduction in the risk of maternal and neonatal hypoglycemia in the use of metformin.
Diabetes, Gestational ; Glycemic Control ; Insulin ; Metformin

Metformin has been used for the treatment of type II diabetes mellitus for decades due to its safety, low cost, and outstanding hypoglycemic effect clinically. The mechanisms underlying these benefits are complex and still not fully understood. Inhibition of mitochondrial respiratory-chain complex I is the most described downstream mechanism of metformin, leading to reduced ATP production and activation of AMP-activated protein kinase (AMPK). Meanwhile, many novel targets of metformin have been gradually discovered. In recent years, multiple pre-clinical and clinical studies are committed to extend the indications of metformin in addition to diabetes. Herein, we summarized the benefits of metformin in four types of diseases, including metabolic associated diseases, cancer, aging and age-related diseases, neurological disorders. We comprehensively discussed the pharmacokinetic properties and the mechanisms of action, treatment strategies, the clinical application, the potential risk of metformin in various diseases. This review provides a brief summary of the benefits and concerns of metformin, aiming to interest scientists to consider and explore the common and specific mechanisms and guiding for the further research. Although there have been countless studies of metformin, longitudinal research in each field is still much warranted.
Humans ; Metformin/pharmacokinetics* ; Diabetes Mellitus, Type 2/metabolism* ; Hypoglycemic Agents/pharmacology* ; AMP-Activated Protein Kinases/metabolism* ; Aging

Female ; Humans ; Hypoglycemic Agents/therapeutic use* ; Insulin Resistance ; Metformin/therapeutic use* ; Phosphatidate Phosphatase ; Pioglitazone/therapeutic use* ; Polycystic Ovary Syndrome/genetics*

Metformin has robust glucose-lowering effects and multiple benefits beyond hypoglycemic effects. It can also be used in combination with various hypoglycemic drugs and is cost effective. In the absence of the strong indications of glucagon like peptide-1 receptor agonist (GLP-1RA) or sodium glucose cotransporter 2 inhibitor (SGLT2i) for cardiorenal protection, metformin should be used as the first-line pharmacological treatment for newly diagnosed type 2 diabetes and the basic drug for the combined treatment of hypoglycemic drugs. Metformin does not increase the risk of liver and kidney function damage, but patients with renal dysfunction should adjust the dosage of metformin based on estimated glomerular filtration rate (eGFR) levels. Moreover, the correct use of metformin does not increase the risk of lactic acidosis. Because long-term use of metformin is associated with a decrease in vitamin B₁₂ levels, patients with insufficient intake or absorption of vitamin B₁₂ should be regularly monitored and appropriately supplemented with vitamin B₁₂. In view of the new progress made in the basic and clinical research related to metformin, the consensus updating expert group updated the consensus on the basis of the Expert Consensus on the Clinical Application of Metformin (2018 Edition).
Humans ; Consensus ; Diabetes Mellitus, Type 2/complications* ; Hypoglycemic Agents ; Metformin/therapeutic use* ; Sodium-Glucose Transporter 2 Inhibitors/therapeutic use* ; Vitamins/therapeutic use* ; China

OBJECTIVES: Metformin is the basic drug for treating diabetes, and the plateau hypoxic environment is an important factor affecting the pharmacokinetics of metformin, but there have been no reports of metformin pharmacokinetic parameters in patients with diabetes mellitus type 2 (T2DM) in the high-altitude hypoxic environment. This study aims to investigate the effect of the hypoxic environment on the pharmacokinetics and assess the efficacy and safety of metformin administration in patients with Type 2 diabetes mellitus (T2DM). METHODS: A total of 85 patients with T2DM taking metformin tablets in the plateau group (n=32, altitude: 1 500 m) and control group (n=53, altitude: 3 800 m) were enrolled according to the inclusion and exclusion criteria, and 172 blood samples were collected in the plateau group and the control Group. A ultra-performance liquid chromatography/tandem mass spectrometry (UFLC-MS/MS) method was established to determine the blood concentration of metformin, and Phoenix NLME software was used to establish a model of pharmacokinetics of metformin in the Chinese T2DM population. The efficacy and serious adverse effects of metformin were compared between the 2 groups. RESULTS: The population pharmacokinetic modeling results showed that plateau hypoxia and age were the main covariates for model building, and the pharmacokinetic parameters were significantly different between the plateau and control groups (all P<0.05), including distribution volume (V), clearance (CL), elimination rate constant (Ke), half-life(T_1/2), area under the curve (AUC), time to reach maximum concentration (T_max). Compared with the control group, AUC was increased by 23.5%, T_max and T_1/2 were prolonged by 35.8% and 11.7%, respectively, and CL was decreased by 31.9% in the plateau group. The pharmacodynamic results showed that the hypoglycaemic effect of T2DM patients in the plateau group was similar to that in the control group, the concentration of lactic acid was higher in the plateau group than that in the control group, and the risk of lactic acidosis was increased after taking metformin in the plateau population. CONCLUSIONS Metformin metabolism is slowed down in T2DM patients in the hypoxic environment of the plateau; the glucose-lowering effect of the plateau is similar, and the attainment rate is low, the possibility of having serious adverse effects of lactic acidosis is higher in T2DM patients on the plateau than on the control one. It is probably suggested that patients with T2DM on the plateau can achieve glucose lowering effect by extending the interval between medication doses and enhancing medication education to improve patient compliance.
Humans ; Diabetes Mellitus, Type 2/drug therapy* ; Metformin/therapeutic use* ; Acidosis, Lactic ; Tandem Mass Spectrometry ; Hypoxia ; Glucose