Melmet 500Mg

PHARMACOLOGICAL CATEGORY

Blood glucose lowering drugs. Biguanides.

PHARMACOLOGY

Metformin is a Biguanides with antihyperglycemic effects. lowering both basal and postprandial plasma glucose It does not stimulate insulin secretion and therefore does not produce hypoglycemia. Metformin may act via 3 mechanisms: Reduction of hepatic glucose production by inhibiting gluconeogenesis and glycogenolysis. In muscle. by increasing insulin sensitivity. improving peripheral glucose uptake and utilization. And delay of intestinal glucose absorption, Metformin stimulates intracellular glycogen synthesis by acting on glycogen synthase. Metformin increases the transport capacity of all types of membrane glucose transporters (GLUTs) known to date. 

PHARMACOKINETICS

Absorption: After an oral dose of metformin hydrochloride tablet. maximum plasma concentration (C….) is reached in approximately 2.5 hours (t….) Absolute bioavailability of a 500 mg or 850 mg metformin hydrochloride tablet is approximately 50-60% in healthy subjects After an oral dose, the non-absorbed fraction recovered in faces was 20-30%. After oral administration, metformin absorption is saturable and incomplete. It is assumed that the pharmacokinetics of metformin absorption is non-linear. At the recommended metformin doses and dosing schedules, Steady State plasma concentrations are reached within 24 to 48 hours and are generally less than 1 microgram/ml. In controlled clinical trials, maximum metformin plasma levels (C.…) did not exceed 5 microgram/ml, even at maximum doses. Food decreases the extent and slightly delays the absorption of metformin. Following oral administration of an 850 mg tablet, a 40% lower plasma peak concentration, a 25% decrease in AUC (area under the curve) and a 35-minute prolongation of the time to peak plasma concentration were observed. The clinical relevance of these findings is unknown. Distribution: Plasma protein binding is negligible. Metformin partitions into erythrocytes. The blood peak is lower than the plasma peak and appears at approximately the same time. The red blood cells most likely represent a secondary compartment of distribution. The mean volume of distribution (Vd) ranged between 63-2761. Metabolism: Metformin is excreted unchanged in the urine. No metabolites have been identified in humans. Elimination: Renal clearance of metformin is > 400 ml/min, indicating that metformin IS eliminated by glomerular filtration and tubular secretion. Following an oral dose. the apparent terminal elimination half-life is approximately 6.5 hours. When renal function is impaired. renal clearance is decreased in proportion to that of creatinine and thus the elimination half-life is prolonged, leading to increased levels of metformin in plasma.

INDICATIONS

Diabetes mellitus. Polycystic ovary syndrome.

CONTRAINDICATIONS

Acute metabolic acidosis (including lactic acidosis and diabetic ketoacidosis). 

SIDE EFFECTS/ADVERSE EFFECTS

Common or very common: Abdominal pain; anorexia; diarrhea (usually transient); nausea; taste disturbance; vomiting. Rare: Decreased vitamin-B, absorption: erythema lactic acidosis (withdraw treatment): pruritus; urticaria. Frequency not known: Hepatitis. Side-effects. further information: Gastro-intestinal effects: Gastro-intestinal side-effects are initially common with metformin. and may persist in some patients, particularly when very high doses are given. A slow increase in dose may improve tolerability.

OVERDOSAGE & TREATMENT

Hypoglycemia has not been seen with metformin hydrochloride doses of up to 85 g, although lactic acidosis has occurred in such circumstances. High overdose of metformin or concomitant risks may lead to lactic acidosis. Lactic acidosis is a medical emergency and must be treated in hospital.

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