METFORMIN

Metformin Hydrochloride Extended-Release Tablets, USP Metformin hydrochloride extended-release tablets, USP are oral antihyperglycemic drugs used in the management of type 2 diabetes. Metformin hydrochloride, USP (N,Ndimethyl- monohydrochloride,Imidodicarbonimidic diamide) is not chemically or pharmacologically related to any other classes of oral antihyperglycemic agents. The structural formula is as shown: Metformin hydrochloride, USP is a white or almost white, crystalline powder with a molecular formula of C4H11N5•HCl and a molecular weight of 165.62. Metformin hydrochloride is freely soluble in water, slightly soluble in alcohol, practically insoluble in acetone and in Methylene chloride. The pKa of metformin is 12.4. The pH of a 1% aqueous solution of metformin hydrochloride is 6.35. Metformin hydrochloride extended-release tablets, USP contain 500 mg or 750 mg of metformin hydrochloride as the active ingredient. Metformin hydrochloride extended-release tablets, USP 500 mg and 750 mg tablets contain the inactive ingredients hypromellose, magnesium stearate, and polyvinyl pyrrolidone. Dissolution Method: Test 10 System Components and Performance - Metformin hydrochloride extended-release tablets, USP comprises a dual hydrophilic polymer matrix system. Metformin hydrochloride, USP is combined with a drug release controlling polymer to form an "inner" phase, which is then incorporated as discrete particles into an "external" phase of a second polymer. After administration, fluid from the gastrointestinal (GI) tract enters the tablet, causing the polymers to hydrate and swell. Drug is released slowly from the dosage form by a process of diffusion through the gel matrix that is essentially independent of pH. The hydrated polymer system is not rigid and is expected to be broken up by normal peristalsis in the GI tract. The biologically inert components of the tablet may occasionally remain intact during GI transit and will be eliminated in the feces as a soft, hydrated mass. DESCRIPTION

INDICATIONS & USAGE Metformin hydrochloride extended-release tablets, USP are indicated as an adjunct to diet and exercise to improve glycemic control in patients with type 2 diabetes mellitus.

There is no fixed dosage regimen for the management of hyperglycemia in patients with type 2 diabetes with metformin hydrochloride extended-release tablets, USP or any other pharmacologic agent. Dosage of metformin hydrochloride extended-release tablets, USP must be individualized on the basis of both effectiveness and tolerance, while not exceeding the maximum recommended daily doses. The maximum recommended daily dose of metformin hydrochloride extended-release tablets, USP in adults is 2000 mg. Metformin hydrochloride extended-release tablets, USP should generally be given once daily with the evening meal. Metformin hydrochloride extended-release tablets, USP should be started at a low dose, with gradual dose escalation, both to reduce gastrointestinal side effects and to permit identification of the minimum dose required for adequate glycemic control of the patient. During treatment initiation and dose titration (see Recommended Dosing Schedule), fasting plasma glucose should be used to determine the therapeutic response to metformin hydrochloride extended-release tablets, USP and identify the minimum effective dose for the patient. Thereafter, glycosylated hemoglobin should be measured at intervals of approximately 3 months. The therapeutic goal should be to decrease both fasting plasma glucose and glycosylated hemoglobin levels to normal or near normal by using the lowest effective dose of metformin hydrochloride extended-release tablets, USP either when used as monotherapy or in combination with sulfonylurea or insulin. Monitoring of blood glucose and glycosylated hemoglobin will also permit detection of primary failure, i.e., inadequate lowering of blood glucose at the maximum recommended dose of medication, and secondary failure, i.e., loss of an adequate blood glucose lowering response after an initial period of effectiveness. Short-term administration of metformin hydrochloride extended-release tablets, USP may be sufficient during periods of transient loss of control in patients usually well-controlled on diet alone. Metformin hydrochloride extended-release tablets, USP must be swallowed whole and never crushed or chewed. Occasionally, the inactive ingredients of metformin hydrochloride extended-release tablets, USP will be eliminated in the feces as a soft, hydrated mass. (See Patient Information printed below.) Recommended Dosing Schedule Adults In general, clinically significant responses are not seen at doses below 1500 mg per day. However, a lower recommended starting dose and gradually increased dosage is advised to minimize gastrointestinal symptoms. The usual starting dose of metformin hydrochloride extended-release tablets, USP is 500 mg once daily with the evening meal. Dosage increases should be made in increments of 500 mg weekly, up to a maximum of 2000 mg once daily with the evening meal. If glycemic control is not achieved on metformin hydrochloride extended-release tablets, USP 2000 mg once daily, a trial of metformin hydrochloride extended-release tablets, USP 1000 mg twice daily should be considered. (See CLINICAL PHARMACOLOGY: CLINICAL STUDIES.) In a randomized trial, patients currently treated with metformin hydrochloride tablets were switched to metformin hydrochloride extended-release tablets. Results of this trial suggest that patients receiving metformin hydrochloride tablets treatment may be safely switched to metformin hydrochloride extended-release tablets once daily at the same total daily dose, up to 2000 mg once daily. Following a switch from metformin hydrochloride tablets to metformin hydrochloride extended-release tablets, glycemic control should be closely monitored and dosage adjustments made accordingly (see CLINICAL PHARMACOLOGY: CLINICAL STUDIES). Pediatrics Safety and effectiveness of metformin hydrochloride extended-release tablets, USP in pediatric patients have not been established. Recommendations for Use in Renal Impairment 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 m2. Initiation of metformin hydrochloride extended-release tablets in patients with an eGFR between 30 to 45 mL/minute/1.73 m2 is not recommended. In patients taking metformin hydrochloride extended-release tablets whose eGFR later falls below 45 mL/min/1.73 m2, assess the benefit risk of continuing therapy. Discontinue metformin hydrochloride extended-release tablets if the patients eGFR later falls below 30 mL/minute/1.73 m2 (See WARNINGS and PRECAUTIONS). Discontinuation for Iodinated Contrast Imaging Procedure 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. Concomitant Metformin Hydrochloride Extended-Release Tablets, USP and Oral Sulfonylurea Therapy in Adult Patients If patients have not responded to 4 weeks of the maximum dose of metformin hydrochloride extended-release tablets monotherapy, consideration should be given to gradual addition of an oral sulfonylurea while continuing metformin hydrochloride extended-release tablets, USP at the maximum dose, even if prior primary or secondary failure to a sulfonylurea has occurred. Clinical and pharmacokinetic drug- drug interaction data are currently available only for metformin plus glyburide (glibenclamide). With concomitant metformin hydrochloride extended-release tablets and sulfonylurea therapy, the desired control of blood glucose may be obtained by adjusting the dose of each drug. In a clinical trial of patients with type 2 diabetes and prior failure on glyburide, patients started on metformin hydrochloride tablets 500 mg and glyburide 20 mg were titrated to 1000/20 mg, 1500/20 mg, 2000/20 mg or 2500/20 mg of metformin hydrochloride tablets and glyburide, respectively, to reach the goal of glycemic control as measured by FPG, HbA1c and plasma glucose response (see CLINICAL PHARMACOLOGY: CLINICAL STUDIES). However, attempts should be made to identify the minimum effective dose of each drug to achieve this goal. With concomitant metformin hydrochloride extended-release tablets, USP and sulfonylurea therapy, the risk of hypoglycemia associated with sulfonylurea therapy continues and may be increased. Appropriate precautions should be taken. (See Package Insert of the respective sulfonylurea.) If patients have not satisfactorily responded to 1 to 3 months of concomitant therapy with the maximum dose of metformin hydrochloride extended-release tabletsand the maximum dose of an oral sulfonylurea, consider therapeutic alternatives including switching to insulin with or without metformin hydrochloride extended-release tablets. Concomitant Metformin Hydrochloride Extended-Release Tablets and Insulin Therapy in Adult Patients The current insulin dose should be continued upon initiation of metformin hydrochloride extended-release tablets therapy. Metformin hydrochloride extended-release tablets therapy should be initiated at 500 mg once daily in patients on insulin therapy. For patients not responding adequately, the dose of metformin hydrochloride extended-release tablets should be increased by 500 mg after approximately 1 week and by 500 mg every week thereafter until adequate glycemic control is achieved. The maximum recommended daily dose is 2000 mg for metformin hydrochloride extended-release tablets. It is recommended that the insulin dose be decreased by 10% to 25% when fasting plasma glucose concentrations decrease to less than 120 mg/dL in patients receiving concomitant insulin and metformin hydrochloride extended-release tablets, USP. Further adjustment should be individualized based on glucose-lowering response. Specific Patient Populations Metformin hydrochloride extended-release tablets is not recommended for use in pregnancy. Metformin hydrochloride extended-release tablets, USP is not recommended in pediatric patients (below the age of 17 years). The initial and maintenance dosing of metformin hydrochloride extended-release tablets should be conservative in patients with advanced age, due to the potential for decreased renal function in this population. Any dosage adjustment should be based on a careful assessment of renal function. Generally, elderly, debilitated, and malnourished patients should not be titrated to the maximum dose of metformin hydrochloride extended-release tablets. Monitoring of renal function is necessary to aid in prevention of lactic acidosis, particularly in the elderly. (See WARNINGS.)

Metformin hydrochloride extended-release tablets, USP are contraindicated in patients with: 1. Severe Renal Impairment (eGFR below 30mL/min/1.73m2) (see WARNINGS and PRECAUTIONS). 2.Known hypersensitivity to metformin hydrochloride, USP. 3.Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. Diabetic ketoacidosis should be treated with insulin.

In A US double blind clinical study of metformin hydrochloride tablets in patients with type 2 diabetes, a total of 141 patients received metformin hydrochloride tablets therapy (up to 2550 mg per day) and 145 patients received placebo. Adverse reactions reported in greater than 5% of the metformin hydrochloride tablets patients, and that were more common in metformin hydrochloride tablets than placebo treated patients, are listed in Table 6. Table 6: Most Common Adverse Reactions (>5 Percent) in a Placebo-Controlled Clinical Study of Metformin Hydrochloride Tablets Monotherapy* Diarrhea 53.2 11.7 Nausea/Vomiting 25.5 8.3 Flatulence 12.1 5.5 Asthenia 9.2 5.5 Indigestion 7.1 4.1 Abdominal Discomfort 6.4 4.8 Headache 5.7 4.8 *Reactions that were more common in metformin hydrochloride tablets than placebo treated patients. Diarrhea led to discontinuation of study medication in 6% of patients treated with metformin hydrochloride tablets. Additionally, the following adverse reactions were reported in ≥1 - ≤5% of metformin hydrochloride tablets patients and myalgia, lightheaded, dyspnea, nail disorder, rash, sweating increased, taste disorder, chest discomfort, chills, flu syndrome, flushing, and palpitation. In worldwide clinical trials over 900 patients with type 2 diabetes have been treated with metformin hydrochloride extended-release tablets in placebo and active controlled studies. In placebo controlled trails, 781 patients were administered metformin hydrochloride extended-release tablets and 195 patients received placebo. 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 7. Table 7: Most Common Adverse Reactions (>5 Percent) in Placebo-Controlled Studies of Metformin Hydrochloride Extended-Release Tablets* Metformin Hydrochloride Extended-Release Tablets(N=781) Placebo (N=195) Adverse Reactions % of patients Diarrhea 9.6 2.6 Nausea/Vomiting 6.5 1.5 Diarrhea led to discontinuation of study medication in 0.6% of patients treated with metformin hydrochloride extended-release tablets. Additionally, the following adverse reactions were reported in ≥1 - ≤5% 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.*Reactions that were more common in metformin hydrochloride extended-release tablets than placebo treated patients.