Simplified monitoring of aminoglycoside treatment

Abstract

Aminoglycosides are effective but toxic antibiotics. They are usually administered by repeated daily injections with the dosage adjusted according to twice-weakly monitoring of serum concentrations. A recent study involving 60 patients with severe infections proposed simplified administration and monitoring of aminoglycosides. The patients were randomly treated with either gentamicin or netilmicin given by once daily or thrice daily injections. No difference was found in efficacy or in toxicity between the various groups. In drugs excreted by glomerular filtration, the daily dose should be proportional to renal clearance. This we assessed by aminoglycoside clearance, calculated from trough and peak concentrations of the drug in serum. We also estimated creatinine clearance by a simple equation derived from the knowledge that the urinary excretion of creatinine is proportional to the muscle mass, decreasing with age. For women, creatinine clearance (ml/min) should be [150.age (years)].body weight (kg)/serum creatinine (mumol/l). For men less than 70 years, the figure 150 should be substituted by 170, and at 70 years or older, by 160. We used 51Cr-EDTA clearance as an independent arbiter to decide which mode was best suited for monitoring aminoglycoside therapy. The results showed that estimated creatinine clearance corresponded better to 51Cr-EDTA clearance than did aminoglycoside clearance based on assay of serum concentrations (correlation coefficients for patients with single-dose treatment 0.81 vs. 0.72). In the study we monitored aminoglycoside treatment in the conventional manner according to the patient's weight and adjusted the dose after assay of the drug's serum concentration.(ABSTRACT TRUNCATED AT 250 WORDS)