[Drug-to-drug interactions and pharmaceutical advice]

To describe suspects of drug interactions in primary health care.

Descriptive and transversal study during 1 month.

Urban health center, primary care, Madrid (Spain).

Patients were treated simultaneously with more than 1 drug (145), 2 general practitioners (GP) and 1 pharmacist.

GP registered in a sheet-form data from diagnostic and pharmacological treatments. The pharmacist checked the sheet-forms to detect drug interactions, and later assessed to the GP about it. The proposals were classified in 3 ways: no change in treatment; to modify or stop the current treatment, and to monitor plasmatic level or clinical parameters.

333 drug interactions were detected in 145 patients. The 67.5% of interactions produced by 7 groups of drugs: theophylines, diuretics, antacids, benzodiacepines, betablockers, NSAID's and ACE's. GP accepted 74% of pharmacist's proposals (recommendations).

Seven types of drugs were involved in the main interactions in primary care. The drug interactions increased as more drugs takes a patient in an accelerated trend. Older than 55 were the most affected. GP accepted 3/4 of the recommended pharmacist proposals.