Overmedication of the low-weight elderly.

This study analyzes age, weight, and drug doses using cimetidine hydrochloride, flurazepam hydrochloride, and digoxin as tracers. Data were obtained for 1797 patients (mean age, 72 years) filling consecutive prescriptions from a national pharmacy service. With all three drugs, patients with lower weight received substantially higher doses with correlations of weight vs dose, based on milligrams per kilogram of body weight, ranging from -0.34 to -0.40. Because body weight declines with increasing age, lower-weight patients are also older and at greatest risk for drug toxicity. Patients weighing 50 kg or less (n = 155) received milligram-per-kilogram doses that were 31% to 46% higher than the group mean and 70% to 88% higher than patients weighing more than 90 kg. For all three study drugs, as patient weight declines, the mean milligram-per-kilogram dose rose sharply. There was no trend seen toward reducing doses for older patients. Low body weight, in addition to advanced age, is a major risk factor for overmedication. Physicians must recognize the need to reduce drug doses for their low-weight elderly patients.