Metformin hydrochloride
Metformin hydrochloride (Glucophage)
Metformin hydrochloride
(met-FOR-min)
Pregnancy Category: B Apo-Metformin Gen-Metformin Glucophage Glycon Novo-Metformin Nu-Metformin PMS-Metformin (Rx)

Classification: Oral antidiabetic

Action/Kinetics: Decreases hepatic glucose production, decreases intestinal absorption of glucose, and increases peripheral uptake and utilization of glucose. Does not cause hypoglycemia in either diabetic or nondiabetic clients, and it does not cause hyperinsulinemia. Insulin secretion remains unchanged, while fasting insulin levels and day-long plasma insulin response may decrease. In contrast to sulfonylureas, the body weight of clients treated with metformin remains stable or may decrease somewhat. Food decreases and slightly delays the absorption of metformin. Negligibly bound to plasma protein; steady-state plasma levels (less than 1 mcg/mL) are reached within 24-48 hr. Excreted unchanged in the urine; no biliary excretion. t1/2, plasma elimination: 6.2 hr. The plasma and blood half-lives are prolonged in decreased renal function.

Uses: Alone as an adjunct to diet to lower blood glucose in clients having NIDDM whose blood glucose cannot be managed satisfactorily via diet alone. Also, metformin may be used concomitantly with a sulfonylurea when diet and metformin or a sulfonylurea alone do not result in adequate control of blood glucose. Use with insulin in type 2 diabetes.

Contraindications: Renal disease or dysfunction (serum creatinine levels greater than 1.5 mg/dL in males and greater than 1.4 mg/dL in females) or abnormal C_CR due to cardiovascular collapse, acute MI, or septicemia. In clients undergoing radiologic studies using iodinated contrast media, because use of such products may cause alteration of renal function, leading to acute renal failure and lactic acidosis. Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. Lactation.

Special Concerns: Cardiovascular collapse, acute CHF, acute MI, and other conditions characterized by hypoxia have been associated with lactic acidosis, which may also be caused by metformin. Use of oral hypoglycemic agents may increase the risk of cardiovascular mortality. Although hypoglycemia does not usually occur with metformin, it may result with deficient caloric intake, with strenuous exercise not supplemented by increased intake of calories, or when metformin is taken with sulfonylureas or alcohol. Because of age-related decreases in renal function, use with caution as age increases. Safety and efficacy have not been determined in children.

Side Effects: Metabolic: Lactic acidosis (fatal in approximately 50% of cases). GI: Diarrhea, N&V;, abdominal bloating, flatulence, anorexia, unpleasant or metallic taste. Hematologic: Asymptomatic subnormal serum vitamin B₁₂ levels.

Overdose Management: Symptoms: Lactic acidosis.

Drug Interactions: Alcohol / Metformin effect on lactate metabolism Cimetidine / (by 60%) Peak metformin plasma and whole blood levels Furosemide / Metformin plasma and blood levels; also, metformin the half-life of furosemide Iodinated contrast media / Risk of acute renal failure and lactic acidosis Nifedipine / Absorption of metformin, leading to plasma metformin levels

How Supplied: Tablet: 500 mg, 850 mg

Dosage
•Tablets NIDDM.
Adults, using 500-mg tablet: Starting dose is one 500-mg tablet b.i.d. given with the morning and evening meals. Dosage increases may be made in increments of 500 mg every week, given in divided doses, up to a maximum of 2,500 mg/day. If a 2,500-mg daily dose is required, it may be better tolerated when given in divided doses t.i.d. with meals. Adults, using 850-mg tablet: Starting dose is 850 mg once daily given with the morning meal. Dosage increases may be made in increments of 850 mg every other week, given in divided doses, up to a maximum of 2,550 mg/day. Usual maintenance dose: 850 mg b.i.d. with the morning and evening meals. However, some clients may require 850 mg t.i.d. with meals.