High-Risk Patients and Drug Interactions The magnitude of the drug interactions problem increases significantly in certain patient populations and as the number of medications taken each day increases. Drug interactions that may be of minor clinical significance in patients with less severe forms of a disease can cause significant exacerbation of the clinical condition in patients with more severe forms of the disease (TABLE 1). Patient populations at high risk include the elderly, critical care patients, and patients undergoing complicated surgical procedures. The elderly population is at high risk because of the number of medications consumed, complicated drug regimens, and clinical states often presented. About 80% of elderly patients routinely take prescription and nonprescription medications concurrently. Some patients may see multiple physicians for acute and chronic conditions, as well as obtain medication from more than one community pharmacy. 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 dose-response curve or potent pharmacologic effects. A listing of drugs with a narrow therapeutic index appears in TABLE 2. 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. Examples of such drugs include corticosteroids, carbamazepine, quinidine, oral contraceptives, and rifampin. Patients receiving drugs with a narrow therapeutic index should be monitored closely for possible clinically significant drug interactions. |
Drug Interactions
 | |  | |  | |  | |  | |  |