Each film coated tablet contains Metformin hydrochloride 500 mg.
Pharmacology: Pharmacokinetics: Metformin Hydrochloride is slowly and incompletely absorbed from the gastrointestinal tract; the absolute bioavailability of a single 500 mg dose is reported to be about 50 to 60%, although this is reduced somewhat if taken with food. Once absorbed, protein binding in plasma is negligible; the drug is excreted unchanged in the urine. The plasma elimination half-life is reported to range from about 2 to 6 hours after oral doses. Metformin crosses the placenta and is distributed into breast milk in small amounts.
It is used in the treatment of type 2 diabetes mellitus.
Tablets should be taken in divided doses with meals in combination therapy with either a sulfonylurea or insulin, diabetic control should be checked by blood sugar readings because of the possibility of glycaemia.
The dose should be increased gradually. One 500 mg tablet 3 times a day or two 850 mg tablets 2 times a day is often enough to give good diabetic control. This may be achieved within a few days, but it is not unusual for the full effect to be delayed for up to 2 weeks. If control is incomplete, a cautious increase in dosage to a maximum of 3 g daily is justified. Once control has been obtained, it may be possible to reduce the dosage. When combined with existing sulfonylurea therapy, which is not given adequate control, one 500 mg tablet should be added initially, the dosage of Metformin being gradually increased until optimal control is obtained. Often, the sulfonylurea may be reduced and in some patients, withdrawn. Metformin can then be continued as the sole therapy.
Symptoms: Hypoglycaemia is not normally a problem encountered with Metformin when used in alone. In combination therapy with sulfonylurea or insulin with alcohol, hypoglycemia can occur. In excessive dosage and particularly, if there is a possibility of accumulation, lactic acidosis should be suspected. Some of the signs & symptoms suggestive of this condition are nausea, diarrhea, abdominal pain and dyspnea.
Treatment: Intensive supportive therapy is recommended which should be particularly directed at correcting fluid loss and metabolic disturbance.
Metformin is contraindicated in patients with renal disease or renal function, congestive heart failure requiring pharmacologic treatment, known hypersensitivity to metformin hydrochloride and acute or chronic metabolic acidosis including diabetic ketoacidosis, with or without coma.
Diabetic ketoacidosis should be treated with insulin.
Metformin should be temporarily discontinued in patients undergoing radiologic studies involving intravascular administration of iodinated contrast materials, because use of such products may result in acute alteration of renal function.
Lactic acidosis is a rare, but serious, metabolic complication that can occur due to metformin accumulation during treatment with Metformin when it occurs. It is fatal in approximately 50% of cases. Lactic acidosis may also occur in association with a number of pathophysiologic conditions, including diabetes mellitus, and whenever there is significant tissue hypoperfusion and hypoxemia. Lactic acidosis is characterized by elevated blood lactate levels, decreased blood pH, electrolyte disturbances with an increase anion gap, and an increased lactate/pyruvate ratio.
Biguanides should not be given to patients with even mild renal impairment, as it may predispose patients to lactic acidosis, and renal function should be monitored throughout therapy.
Gastrointestinal adverse effects including anorexia, nausea, vomiting, and diarrhea may occur with biguanides; patients may experience taste disturbance and there maybe weight loss. Absorption of various substances including vitamin B12 maybe impaired. Skin reactions have been reported rarely.
Hypoglycaemia is rare with a biguanide given alone, although it may occur if other contributing factors or drugs are present.
Lactic acidosis, sometimes fatal, has occurred with biguanides, primarily with phenformin. When it has occurred with metformin most cases have been in patients whose condition contraindicated the use of the drug, particularly those with renal impairment.
Use of a biguanide with other drugs that lower blood-glucose concentrations increases the risk of hypoglycaemia, while drugs that increase blood glucose may reduce the effect of biguanide therapy.
In general fewer drug interactions have been reported with biguanides than with sulfonylureas. Alcohol may increase the risk of lactic acidosis as well as of hypoglycaemia. Care should be taken if biguanides given with drugs that may impair renal function.
Store at temperatures not exceeding 30°C.
A10BA02 - metformin ; Belongs to the class of biguanides. Used in the treatment of diabetes.