हिन्दी (Hindi) मे पढ़िये
The specialty of metformin is that it is the only anti-diabetic drug that reduces the chances of heart attack and stroke even in low doses. This action occurs exclusive of its blood glucose lowering action. Unlike many other anti-diabetic drugs it does not cause weight gain. Hence it is preferred in fat patients. It is usually the first drug to be given in all patients with diabetes. In some conditions, however, metformin is better avoided. Patients with kidney disease, liver disease, heart disease, those who consume too much alcohol are candidates in whom this drug should be avoided.
Metformin is started at a low dose and taken with meals and gradually the dose is increased to its maximum. That way patients tolerate the drug better. Common side effects of the drug are bloating, nausea and diarrhoea. It may be combined with other anti-diabetic agents like sulphonylureas or insulin. Metformin should be stopped before giving intravenous contrast drugs during x-rays and scans.
Two drugs falling in this class are repaglinide and nateglinide. Meglitinides bind to a different part of the sulphonylurea receptor on the beta cells of the islets of Langerhans (See Diagram). But their action is similar to that of sulphonylureas. They stimulate the early release of insulin from the beta cells. They suppress the immediate rise of blood glucose after a meal if given 15 minutes before the meal. It is useful for those patients who have a selective rise of blood glucose after food but normal fasting blood glucose levels. This condition is known as post prandial hyperglycaemia. As the drug is rapid acting it can be compared to insulin. It is specially suitable for persons with erratic meal patterns. The drug needs to be taken only before meals and may be skipped if no meal is taken.
Two drugs in this class also known as glitazones are pioglitazone and rosiglitazone. They act on nuclear receptors present inside the cell. As shown in the diagram there can be receptors for external molecules on the cell membrane. Similarly there exist receptors on the nuclear membrane. Thiazolidinediones bind to these nuclear receptors called PPARγ and activate a certain portion of the genome. Activation of this part of the genome causes production of proteins which increase the uptake of glucose and fatty acids into the cell. Thus basically they assist in the action of insulin. They are useful as combination therapy with other antidiabetic drugs like sulphonylureas. They should be used cautiously in combination with insulin because of their propensity to retain water in the body and thereby cause swelling. They should be avoided in patients with heart failure and liver disease. These drugs produce their blood glucose lowering effect slowly which may be apparent after 2 to 3 months. Very recently the European Medicines Agency has recommended suspension of Rosiglitazone considering the risk posed to the heart. The Food and Drug Administration, USA has also restricted the use of Rosiglitazone.