Pharmacokinetics of amikacin in elderly patients during repeated intramuscular administration. The aim of the study was to evaluate a standard dosage of Amikacin, 7.5 mg/kg every 12 hours, in elderly subjects whose renal function was reduced by half, in view of the narrow therapeutic interval of the aminoglycosides. Twelve subjects, aged from 72 to 96 years (mean age: 82 years; mean weight: 58.7 kg) and suffering from severe infections, were therefore treated with intramuscular Amikacin as monotherapy at the dosage of 7.5 mg/kg repeated every 12 hours for 5 days. Clinical, biological (creatinine clearance estimated by the method of Cockroft) and bacteriological data were recorded on D0 and D5. The pharmacokinetic study included plasma Amikacin assays at the following times: D0 (control), D1 (1h, 3h, 6h, 12h), D2 (24h, 25h, 27h, 36h), D3 (48h, 49h), D5 (96h, 97h, 99h, 102h, 105h, 108h), D6 (120h, 132h). Clinical success was observed in 9 out of the 12 cases, with no undesirable side effects. At this age and at this dosage, peak concentrations (Cmax) remain close to the required "therapeutic" levels, 25 to 30 mcg/ml; the residual concentrations (Cmin), highly-correlated with creatinine clearance values, are also close to the desired levels (4-10 mcg/ml). The absence of side effects, and in particular the lack of renal side effects, during this treatment trial suggest that the usual dosage of Amikacin IM, 7.5 mg/kg/12 h, need not be reduced in elderly subjects if creatinine clearance remains above 30 ml/mn and if the treatment is of short duration.