Drug can be useful tools in the prevention and treatment of Symptoms and Diseases, but if not used properly, they may be Harmful and cause new symptoms (or) produce suboptimal effects. Most drugs have multiple pharmacologic effects in patients, specially the newer, more complex drugs being marketed. Clinically significant drug interactions can occur when two or more drugs are taken in combination. The resulting pharmacological action (either potentiation or antagonism of the interacting drugs) can be lesser or greater than the total effects of the drugs individual actions. Drugs identified as having a high risk of being involved in a clinically significant drug interaction frequently have a narrow therapeutic index, a very steep doseresponse curve or potent pharmacologic effects. A toxic dose of these drugs may be only slightly above the therapeutic dose. A slight increase in the dose may produce a large increase in serum drug levels and clinical effect. Conversely, a slight decrease in the plasma level of drugs with a steep dose-response curve may result in a significant loss of therapeutic effect. More than 30 medications are introduced each year, and physicians receive frequent mailings about discovered drug interactions. As a result, many physicians feel overwhelmed and question the safety of multiple drugs Regimens. Some drug interactions may seriously harm to the patients.
