Analysis of drug-drug interactions among nursing home residents.

The extent of clinically important drug-drug interactions in the patient population of a nursing home was studied. The administration of medications to all 138 residents of two wards of the hospital-affiliated facility was monitored for 15 days through a review of nurses' medication-administration records and patients' charts. Information on the nature and timing of administered drug combinations was compared with published information to identify potential drug interactions. If a serious drug interaction was suspected, the recorded information was verified through the nurse in charge of that patient. Few of the drug interactions commonly reported to occur in nursing homes were observed at the facility, where drug therapy is monitored by a team of geriatric practitioners that includes two pharmacists. Of the 24 suspected interactions that were identified, 11 had potential clinical importance, and all 11 involved drug combinations that could alter the metabolism or action of one of the drugs. However, only two patients were exposed to any substantial degree of risk, and dosages of the drugs involved were adjusted. An additional 13 patients were taking a combination of drugs that could have altered the intestinal absorption of one of the drugs. Careful timing of drug administration avoided this potential problem. With proper education of the nursing staff, immediate clarification of medication orders, and optimal timing of drug administration, many clinically important drug-drug and drug-food interactions can be avoided in nursing home patients.