BIGUANIDES PREPARATIONS:

These include Metformin and Phenformin drugs which are their generic names. Metformen exerts its effect primarily by increasing the peripheral uptake of glucose. It also enhances intestinal absorption of glucose, if given in large doses; as such its action is in contrast to sulphonylureas. The added advantage of its use is that it does not bring down the blood glucose levels in non-diabetics.

Uses: It is used in the treatment of diabetes mellitus as a primary therapy, in combination with insulin therapy or sulphonylureas.

Contra-indications: Risk of producing lactic acidosis is much more in Metformin than with use of Phenformin. It is more useful in obese and overweight diabetic patients and is used mainly in persons under 65 years, or in cases of renal & hepatic insufficiency, cardiovascular disease, pancreatitis, tissue hypoxia pulmonary embolism, excessive intake of alcohol or concomitant use of diuretics.

Phenformin is said to be comparatively much safer than Metformin, as it does not cause sudden fall in blood sugar level nor is it specifically meant for the obese only. Both are used in ‘Maturing Onset, NIDDM cases, responding inadequately to the dietary treatment, either alone or with sulphonylureas. But phenformin is contra-indicated in metabolic acidosis, infection, coma, gangrene, during or immediately after surgery, shock and hypoxaema, and also not in any cordial, hepatic or renal diseases.
Drug Interactions: Alcohol, diuretics, anti-coagulants.
Side-effects: These include nausea, vomiting, loss of appetite (Anorexia) loose motions metallictaste in the mouth, general weakness, skin eruptions, vassels or even urticaria. Possibility of lactic acidosis is more with phenformin than with the use of Metformin the latest side-effect can occur with the use of both drugs, but less with Metformin.

Dose:

Metformin: Usually 250 mg twice and daily after meals. The dose may be gradually increase even upto 3 gms, (in divided doses), if the situation warrants. As for tapering or enhancing the dose and its frequency, the patient’s doctor is the best guide.

Phenformin: It in available in 25mg tabs or in 50 mg capsules of long-acting duration. 25mg tablets may be taken 1-4 times daily, but must not exceed 100mgs, in total, per 24 hours. As for DBI , T.D.Caps, (Phenformin) usual daily dose is from 50-150mg, during 24 hour’s period but any change in dose & frequency, should always have sanction of the patient’s physician. Both Metformin and phenformin preparations should never be taken on empty stock. Best and preferred time is to take them after breakfast daily. This rule should also be followed by the patients who take sulphonylurea preparations. As a matter of principle, no anti-diabetic drug should ever be taken on an empty stomach. In case of any side-effect or reaction or changer in symptoms, the attending physicans’s must be informed at once, and his advice followed in its entirety.