Get your patient on Metformin Er 500 Mg - Metformin Er 500 Mg tablet (Metformin Er 500 Mg)

Metformin Hydrochloride Extended-Release Tablets
• Swallow metformin hydrochloride extended-release tablets whole and never crush, cut or chew.
• The recommended starting dose of metformin hydrochloride extended-release tablets are 500 mg orally once daily with the evening meal.
• Increase the dose in increments of 500 mg weekly on the basis of glycemic control and tolerability, up to a maximum of 2000 mg once daily with the evening meal.
• If glycemic control is not achieved with metformin hydrochloride extended-release tablets 2000 mg once daily, consider a trial of metformin hydrochloride extended-release tablets 1000 mg twice daily. If higher doses are required, switch to metformin hydrochloride tablets at total daily doses up to 2550 mg administered in divided daily doses, as described above.
• Patients receiving metformin hydrochloride tablets may be switched to metformin hydrochloride extended-release tablets once daily at the same total daily dose, up to 2000 mg once daily.

• Assess renal function prior to initiation of metformin hydrochloride extended-release tablets and periodically thereafter.
• Metformin hydrochloride extended-release tablets are contraindicated in patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m ² .
• Initiation of metformin hydrochloride extended-release tablets in patients with an eGFR between 30 to 45 mL/minute/ 1.73 m ² is not recommended.
• In patients taking metformin hydrochloride extended-release tablets whose eGFR later falls below 45 mL/min/1.73 m ² , assess the benefit risk of continuing therapy.
• Discontinue metformin hydrochloride extended- release tablets if the patient's eGFR later falls below 30 mL/minute/1.73 m ² [see Warnings and Precautions (5.1) ].

Discontinue metformin hydrochloride extended-release tablets at the time of, or prior to, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/min/1.73 m ² ; in patients with a history of liver disease, alcoholism, or heart failure; or in patients who will be administered intra-arterial iodinated contrast. Re-evaluate eGFR 48 hours after the imaging procedure; restart metformin hydrochloride extended-release tablets if renal function is stable.

Risk Summary

Limited data with metformin hydrochloride extended-release tablets in pregnant women are not sufficient to determine a drug-associated risk for major birth defects or miscarriage. Published studies with metformin use during pregnancy have not reported a clear association with metformin and major birth defect or miscarriage risk [see Data ]. There are risks to the mother and fetus associated with poorly controlled diabetes mellitus in pregnancy [see Clinical Considerations ].

No adverse developmental effects were observed when metformin was administered to pregnant Sprague Dawley rats and rabbits during the period of organogenesis at doses up to 2- and 5-times, respectively, a 2550 mg clinical dose, based on body surface area [see Data ].

The estimated background risk of major birth defects is 6 to 10% in women with pre-gestational diabetes mellitus with an HbA1C >7 and has been reported to be as high as 20 to 25% in women with a HbA1C >10. The estimated background risk of miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Clinical Considerations

Disease-associated maternal and/or embryo/fetal risk

Poorly-controlled diabetes mellitus in pregnancy increases the maternal risk for diabetic ketoacidosis, pre-eclampsia, spontaneous abortions, preterm delivery, stillbirth and delivery complications. Poorly controlled diabetes mellitus increases the fetal risk for major birth defects, stillbirth, and macrosomia related morbidity.

Data

Human Data

Published data from post-marketing studies have not reported a clear association with metformin and major birth defects, miscarriage, or adverse maternal or fetal outcomes when metformin was used during pregnancy. However, these studies cannot definitely establish the absence of any metformin-associated risk because of methodological limitations, including small sample size and inconsistent comparator groups.

Animal Data

Metformin hydrochloride did not adversely affect development outcomes when administered to pregnant rats and rabbits at doses up to 600 mg/kg/day. This represents an exposure of about 2 and 5 times a 2550 mg clinical dose based on body surface area comparisons for rats and rabbits, respectively. Determination of fetal concentrations demonstrated a partial placental barrier to metformin.

Risk Summary

Limited published studies report that metformin is present in human milk [see Data ]. However, there is insufficient information to determine the effects of metformin on the breastfed infant and no available information on the effects of metformin on milk production. Therefore, the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for metformin hydrochloride extended-release tablets and any potential adverse effects on the breastfed child from metformin hydrochloride extended-release tablets or from the underlying maternal condition.

Data

Published clinical lactation studies report that metformin is present in human milk which resulted in infant doses approximately 0.11% to 1% of the maternal weight-adjusted dosage and a milk/plasma ratio ranging between 0.13 and 1. However, the studies were not designed to definitely establish the risk of use of metformin during lactation because of small sample size and limited adverse event data collected in infants.

Discuss the potential for unintended pregnancy with premenopausal women as therapy with metformin hydrochloride extended-release tablets may result in ovulation in some anovulatory women.

Metformin Hydrochloride Extended-Release Tablets

Safety and effectiveness of metformin hydrochloride extended-release tablets in pediatric patients have not been established.

Controlled clinical studies of metformin hydrochloride extended-release tablets did not include sufficient numbers of elderly patients to determine whether they respond differently from younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy and the higher risk of lactic acidosis. Assess renal function more frequently in elderly patients [see Warnings and Precautions (5.1) ].

Metformin is substantially excreted by the kidney, and the risk of metformin accumulation and lactic acidosis increases with the degree of renal impairment. Metformin hydrochloride extended-release tablets are contraindicated in severe renal impairment, patients with an estimated glomerular filtration rate (eGFR) below 30 mL/min/1.73 m ² [see Dosage and Administration (2.3), Contraindications (4), Warnings and Precautions (5.1), and Clinical Pharmacology (12.3)].

Use of metformin in patients with hepatic impairment has been associated with some cases of lactic acidosis. Metformin hydrochloride extended-release tablets are not recommended in patients with hepatic impairment. [see Warnings and Precautions (5.1)].

In metformin hydrochloride tablets clinical trials of 29-week duration, a decrease to subnormal levels of previously normal serum vitamin B ₁₂ levels was observed in approximately 7% of patients. Such decrease, possibly due to interference with B ₁₂ absorption from the B ₁₂ -intrinsic factor complex, may be associated with anemia but appears to be rapidly reversible with discontinuation of metformin hydrochloride tablets or vitamin B ₁₂ supplementation. Certain individuals (those with inadequate vitamin B ₁₂ or calcium intake or absorption) appear to be predisposed to developing subnormal vitamin B ₁₂ levels. Measure hematologic parameters on an annual basis and vitamin B ₁₂ at 2 to 3 year intervals in patients on metformin hydrochloride extended-release tablets and manage any abnormalities [see Adverse Reactions (6.1) .

Insulin and insulin secretagogues (e.g., sulfonylurea) are known to cause hypoglycemia. Metformin hydrochloride extended-release tablets may increase the risk of hypoglycemia when combined with insulin and/or an insulin secretagogue. Therefore, a lower dose of insulin or insulin secretagogue may be required to minimize the risk of hypoglycemia when used in combination with metformin hydrochloride extended-release tablets [see Drug Interactions (7) ].

There have been no clinical studies establishing conclusive evidence of macrovascular risk reduction with metformin hydrochloride extended-release tablets.

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Metformin Hydrochloride Extended-Release Tablets

In placebo-controlled trials, 781 patients were administered metformin hydrochloride extended-release tablets. Adverse reactions reported in greater than 5% of the metformin hydrochloride extended release tablets patients, and that were more common in metformin hydrochloride extended-release tablets-than placebo-treated patients, are listed in Table 2.

Table 2: Adverse Reactions from Clinical Trials of Metformin Hydrochloride Extended-Release Tablets Occurring >5% and More Common than Placebo in Patients with Type 2 Diabetes Mellitus

Diarrhea led to discontinuation of metformin hydrochloride extended-release tablets in 0.6% of patients. Additionally, the following adverse reactions were reported in ≥1.0% to ≤5.0% of metformin hydrochloride extended-release tablets patients and were more commonly reported with metformin hydrochloride extended-release tablets than placebo: abdominal pain, constipation, distention abdomen, dyspepsia/heartburn, flatulence, dizziness, headache, upper respiratory infection, taste disturbance.

The following adverse reactions have been identified during post approval use of metformin. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Cholestatic, hepatocellular, and mixed hepatocellular liver injury have been reported with postmarketing use of metformin.

Metformin is an antihyperglycemic agent which improves glucose tolerance in patients with type 2 diabetes mellitus, lowering both basal and postprandial plasma glucose. Metformin decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization. With metformin therapy, insulin secretion remains unchanged while fasting insulin levels and day-long plasma insulin response may decrease.

Absorption

Following a single oral dose of metformin hydrochloride extended-release tablets, C _max is achieved with a median value of 7 hours and a range of 4 to 8 hours. Peak plasma levels are approximately 20% lower compared to the same dose of metformin hydrochloride tablets, however, the extent of absorption (as measured by AUC) is comparable to metformin hydrochloride tablets.

At steady state, the AUC and C _max are less than dose proportional for metformin hydrochloride extended-release tablets within the range of 500 to 2000 mg administered once daily. Peak plasma levels are approximately 0.6, 1.1, 1.4 and 1.8 mcg/mL for 500, 1000, 1500, and 2000 mg once-daily doses, respectively. The extent of metformin absorption (as measured by AUC) from metformin hydrochloride extended-release tablets at a 2000 mg once-daily dose is similar to the same total daily dose administered as metformin hydrochloride tablets 1000 mg twice daily. After repeated administration of metformin hydrochloride extended-release tablets, metformin did not accumulate in plasma.

Effect of food : Food decreases the extent of absorption and slightly delays the absorption of metformin, as shown by approximately a 40% lower mean peak plasma concentration (C _max ), a 25% lower area under the plasma concentration versus time curve (AUC), and a 35-minute prolongation of time to peak plasma concentration (T _max ) following administration of a single 850 mg tablet of metformin hydrochloride tablets with food, compared to the same tablet strength administered fasting.

Although the extent of metformin absorption (as measured by AUC) from the metformin hydrochloride extended-release tablet increased by approximately 50% when given with food, there was no effect of food on C _max and T _max of metformin. Both high and low fat meals had the same effect on the pharmacokinetics of metformin hydrochloride extended-release tablets.

Distribution

The apparent volume of distribution (V/F) of metformin following single oral doses of metformin hydrochloride tablets 850 mg averaged 654 ± 358 L. Metformin is negligibly bound to plasma proteins. Metformin partitions into erythrocytes, most likely as a function of time.

Metabolism

Intravenous single-dose studies in normal subjects demonstrate that metformin is excreted unchanged in the urine and does not undergo hepatic metabolism (no metabolites have been identified in humans) nor biliary excretion.

Elimination

Renal clearance (see Table 4) is approximately 3.5 times greater than creatinine clearance, which indicates that tubular secretion is the major route of metformin elimination. Following oral administration, approximately 90% of the absorbed drug is eliminated via the renal route within the first 24 hours, with a plasma elimination half-life of approximately 6.2 hours. In blood, the elimination half-life is approximately 17.6 hours, suggesting that the erythrocyte mass may be a compartment of distribution.

Specific Populations

Renal Impairment

In patients with decreased renal function the plasma and blood half-life of metformin is prolonged and the renal clearance is decreased (see Table 3) [see Dosage and Administration (2.3), Contraindications (4) , Warnings and Precautions (5.1) and Use in Specific Populations (8.6)].

Hepatic Impairment

No pharmacokinetic studies of metformin have been conducted in patients with hepatic impairment [see Warnings and Precautions (5.1) and Use in Specific Populations (8.7)].

Geriatrics

Limited data from controlled pharmacokinetic studies of metformin hydrochloride tablets in healthy elderly subjects suggest that total plasma clearance of metformin is decreased, the half-life is prolonged, and C _max is increased, compared to healthy young subjects. It appears that the change in metformin pharmacokinetics with aging is primarily accounted for by a change in renal function (see Table 4). [see Warnings and Precautions (5.1) and Use in Specific Populations (8.5)].

Gender

Metformin pharmacokinetic parameters did not differ significantly between normal subjects and patients with type 2 diabetes mellitus when analyzed according to gender (males=19, females=16).

Race

No studies of metformin pharmacokinetic parameters according to race have been performed.

Drug Interactions

In Vivo Assessment of Drug Interactions

Table 5: Effect of Coadministered Drug on Plasma Metformin Systemic Exposure

^• All metformin and coadministered drugs were given as single doses

^† AUC = AUC (INF) unless otherwise noted

^‡ Ratio of arithmetic means, p-value of difference <0.05

^§ AUC _{(0-24 hr)} reported

^¶ Ratio of arithmetic means

Long-term carcinogenicity studies have been performed in rats (dosing duration of 104 weeks) and mice (dosing duration of 91 weeks) at doses up to and including 900 mg/kg/day and 1500 mg/kg/day, respectively. These doses are both approximately 3 times the maximum recommended human daily dose of 2550 mg based on body surface area comparisons. No evidence of carcinogenicity with metformin was found in either male or female mice. Similarly, there was no tumorigenic potential observed with metformin in male rats. There was, however, an increased incidence of benign stromal uterine polyps in female rats treated with 900 mg/kg/day.

There was no evidence of a mutagenic potential of metformin in the following in vitro tests: Ames test ( S. typhimurium ), gene mutation test (mouse lymphoma cells), or chromosomal aberrations test (human lymphocytes). Results in the in vivo mouse micronucleus test were also negative.

Fertility of male or female rats was unaffected by metformin when administered at doses as high as 600 mg/kg/day, which is approximately 2 times the maximum recommended human daily dose of 2550 mg based on body surface area comparisons.

A 24-week, double-blind, placebo-controlled study of metformin hydrochloride extended-release tablets, taken once daily with the evening meal, was conducted in patients with type 2 diabetes mellitus who had failed to achieve glycemic control with diet and exercise. Patients entering the study had a mean baseline HbA of 8.0% and a mean baseline FPG of 176 mg/dL. The treatment dose was increased to 1500 mg 1c once daily if at Week 12 HbA1c was ≥7.0% but <8.0% (patients with HbA ≥8.0% were discontinued from 1c the study). At the final visit (24-week), mean HbA had increased 0.2% from baseline in placebo patients 1c and decreased 0.6% with metformin hydrochloride extended-release tablets.

A 16-week, double-blind, placebo-controlled, dose-response study of metformin hydrochloride extended-release tablets, taken once daily with the evening meal or twice daily with meals, was conducted in patients with type 2 diabetes mellitus who had failed to achieve glycemic control with diet and exercise. The results are shown in Table 10.

Table 10: Mean Changes from Baseline• in HbA1c and Fasting Plasma Glucose at Week 16 Comparing Metformin Hydrochloride Extended-Release Tablets vs Placebo in Patients with Type 2 Diabetes Mellitus

^a All comparisons versus Placebo

Mean baseline body weight was 193 lbs, 192 lbs, 188 lbs, 196 lbs, 193 lbs and 194 lbs in the metformin hydrochloride extended-release tablets 500 mg , 1000 mg, 1500 mg, and 2000 mg once daily, 1000 mg twice daily and placebo arms, respectively. Mean change in body weight from baseline to week 16 was -1.3 lbs, -1.3 lbs, -0.7 lbs, -1.5 lbs, -2.2 lbs and -1.8 lbs, respectively.

A 24-week, double-blind, randomized study of metformin hydrochloride extended-release tablets, taken once daily with the evening meal, and metformin hydrochloride tablets, taken twice daily (with breakfast and evening meal), was conducted in patients with type 2 diabetes mellitus who had been treated with metformin hydrochloride tablets 500 mg twice daily for at least 8 weeks prior to study entry. The results are shown in Table 11.

Table 11: Mean Changes from Baseline• in HbA1c and Fasting Plasma Glucose at Week 24 Comparing Metformin Hydrochloride Extended-Release Tablets vs Metformin Hydrochloride Tablets in Patients with Type 2 Diabetes Mellitus

^†a n=68

Mean baseline body weight was 210 lbs, 203 lbs and 193 lbs in the metformin hydrochloride tablets 500 mg twice daily, and metformin hydrochloride extended-release tablets 1000 mg and 1500 mg once daily arms, respectively. Mean change in body weight from baseline to week 24 was 0.9 lbs, 1.1 lbs and 0.9 lbs, respectively.

Store at 20° to 25°C (68° to 77°F); excursions permitted within 15° to 30°C (59° to 86°F). [See USP Controlled Room Temperature.]

Dispense in light-resistant container.