Tobramycin therapy of serious infections. Pharmacological aspects and side effects

Plasma concentrations and side effects were followed in 52 adults treated with tobramycin for 4-39 days (mean 12.2 days). In order to obtain 1-h peak levels above the recommended 4 microgram/ml in patients with normal renal function, loading doses of 160 mg followed by 100-120 mg every 8 h were usually necessary. Both the leading dose and the mean daily dose of 304 mg were higher than usually recommended. Great individual variations in doses required were found and nomograms were of little value. Reduced maintenance doses were given to patients with impaired renal function. Adequate treatment required plasma level determinations 2-3 times a week. The high dose of tobramycin regimen used in this study implied that 30% of the trough levels exceeded 2 microgram/ml. The frequency of clinically significant side effects were, however, low and the treatment was only interrupted once because of a decrease in renal function. Temporary reduction in renal function probably related to tobramycin was found in 6 patients, and 5 patients got temporary disturbances of vestibular function. One patient experienced a temporary hearing loss and 2 patients a permanent hearing loss, which might have been caused by simultaneous treatment with furosemide and tobramycin.