No abstract

Two hundred fifty-eight patients with suspected sepsis were treated with tobramycin or gentamicin in a prospective, randomized, double-blind trial. One hundred forty-six patients received nine or more doses, had serial determinations of serum creatinine, and were evaluated for nephrotoxicity; 91 were able to cooperate with audiometry and were evaluated for auditory toxicity. Auditory toxicity developed in five of 47 (10 per cent) given gentamicin and five of 44 (11 per cent) given tobramycin. Nephrotoxicity developed in 19 of 72 (26 per cent) given gentamicin and nine of 74 (12 per cent) given tobramycin (P less than 0.025). The severity of the nephrotoxicity was not different; the mean increase in creatinine was 1.3 mg per 100 ml (114.9 mumol per liter) in both groups. Both the tobramycin and gentamicin groups had a similar mean age, initial serum creatinine level, total dose, serum aminoglycoside level, and duration of therapy. We conclude that tobramycin causes nephrotoxicity less frequently than does gentamicin.

Ribavirin is a broad-spectrum antiviral drug that has in vitro activity against human immunodeficiency virus. To determine the kinetics of ribavirin, 17 symptom-free homosexual men with lymphadenopathy were studied. Single doses of ribavirin, 600, 1200, or 2400 mg, were given orally or intravenously. The plasma ribavirin concentration-time profiles were well fitted by a three-compartment open model. Ribavirin followed linear kinetics over the dose range studied. The mean 1-hour postinfusion concentrations after intravenous ribavirin, 600, 1200, and 2400 mg, were 8.0, 19.7, and 37.1 mumol/L, respectively. The mean +/- SD plasma beta-phase half-life, terminal-phase (gamma) half-life, and volume of distribution at steady state were 2.0 +/- 1.1 hours, 35.5 +/- 14.0 hours, and 647 +/- 258 L, respectively. The mean ribavirin renal clearance and total body clearance were 99 +/- 30 and 283 +/- 37 ml/min, respectively. After an oral dose of 600, 1200, and 2400 mg, the mean peak plasma ribavirin concentrations (which occurred 1.5 hours after administration) were 5.1, 9.9, and 12.6 mumol/L, respectively. The mean absorption half-life and bioavailability of ribavirin were 0.5 hour and 45%. Ribavirin had no plasma protein binding and the drug accumulated within red blood cells. In conclusion, ribavirin is incompletely absorbed from the gastrointestinal tract, its renal excretion accounts for approximately one third of the drug's elimination, and drug accumulation (greater than threefold) will result with repetitive dosing at the 6- to 8-hour dosing interval currently used.