These drugs decrease the intestinal absorption of carbohydrates, promote their oxidation in the tissues, and also reduce conversion of fats and proteins into glucose in the liver. They reduce elevated blood glucose levels only and do not produce hypoglycemia (fall in blood glucvose levels below normal).
Biguanides Phenformin (DBI-TD. DBI), Metformin (Glyciphage) Metformin is used alone in obese-diabetics but can be given along with sulfonylureas. Usual dose is 250 mg to 500 mg to be taken thrice a day with meals (maximum 3 g in a day)Adverse Effects: Phenformin causes abdominal discomfort, nausea, vomiting, and diarrhoea in 15% to 25% of cases, but with its sustained release preparation, the frequency of these adverse effects is much less. The most serious adverse effect of this drug is lactic acidosis (accumulation of lactic acid in the body) which not only causes muscular pain in the legs and difficulty in breathing, but can also prove to be fatal. The drug may also cause allergy in the form of skin rashes and itching; in rare cases it may cause allergic shock. Phenformin is rarely used in India. Metformin is a better tolerated drug and is less likely to cause lactic acidosis. Precautions In case of severe abdominal discomfort the drug should be taken along with breakfast.If there are any symptoms of lactic acid accumulation such as pain in the muscle, the drug should be stopped immediately. Also stop the drug if allergic reactions occur.Metformin decreases the absorption of vitamin B12 in high doses.It should be used cautiously by those suffering from a heart, kidney, or liver disease.It causes harmful effects to the unborn child and should not be taken during pregnancy.It should be used with caution by the old and by those who eat poorly or irregularly. Thiazolidinediones Pioglitazone (Piozone, Pioglit), Rosiglitazone (Rosicon, Rosinorm) Pioglitazone: It enhances entry of glucose in muscles and fats. Pioglitazone reduces formation of glucose from fats and proteins in liver. These effects are due to enhanced effects of insulin on tissues and are brought about by changes in functions of gene that regulates fat metabolism. An added advantage is that bad lipids (triglycerides) are reduced and good lipid (HOL) levels are increased. It is not useful in juvenile (type-1) OM. For type-2 OM it can be used alone or in a combination with metformin or glimepiride. Pioglitazone is used in a dose of 15 to 30 mg once a day and its maximum dose is 45 mg per day. Adverse Effects: The drug may increase body weight. It may cause headache, muscle pain and anaemia. Hypoglycemia usually does not occur when pioglitazone is used alone. One requires monitoring of liver function. Women taking oral contraceptives may have unwanted pregnancy due to adverse interaction. Therefore, other methods of preventing pregnancy should be adopted. Rosiglitazone: It has same effects except changes in lipid levels do not occur. It is given in a dose of 2 mg once or twice daily with maximum 8 mg per day.
