Biguanides

SYNTHESIS AND DRUG PROFILE

Biguanides

Mode of action: Biguanides do not have direct action on increasing or decreasing the glucose level. This reduces glucose levels primarily by decreasing hepatic gluconeogenisis by increasing the insulin action on muscles and fat. It also reduces the absorption of glucose from intestine.

i. Phenformin

Synthesis

Route-I. From: 2-Phenylethylamine

Route-II. From: 1-(2-Chloroethyl) benzene

Properties and uses: Used only in stable type II diabetics, it may be used alone or in conjunction with another oral hypoglycaemic agents, such as sulphonylureas or with insulin.

Dose: The normal dose is 25 mg tablets 1–4 times a day, usually 50–150 mg daily with breakfast.

ii. Metformin (Diamet, Diaphage Glyciphage, Glycomet)

Synthesis

Route I. From: Dimethylamine

Route II. From: Dimethylamine

Properties and uses: Metformin hydrochloride exists as white crystals, freely soluble in water, slightly soluble in alcohol, practically insoluble in acetone and methylene chloride. It is usually given along with sulphonylureas.

Assay: Dissolve the sample in anhydrous formic acid, add acetonitrile, and titrate against 0.1 M perchloric acid. Determine the end point potentiometrically.

Dose: Initial dose is 500 mg thrice daily or 850 mg twice daily with meals.

Dosage forms: Metformin tablets B.P.