Biological activity of netilmicin, a broad-spectrum semisynthetic aminoglycoside antibiotic

Netilmicin (Sch 20569) is a new broad-spectrum semisynthetic aminoglycoside derived from sisomicin. Netilmicin was compared to gentamicin, tobramycin, and amikacin in a variety of in vitro test systems as well as in mouse protection tests. Netilmicin was found to be similar in activity to gentamicin against aminoglycoside-susceptible strains in both in vitro and in vivo tests. Netilmicin was also active against many aminoglycoside-resistant strains of gram-negative bacteria, particularly those known to possess adenylating enzymes (ANT 2') or those with a similar resistance pattern. Netilmicin was found to be markedly less toxic than gentamicin in chronic studies in cats, although gentamicin appeared less toxic in acute toxicity tests in mice. The concentrations of netilmicin and gentamicin in serum were compared in dogs after intramuscular dosing, and the pharmacokinetics including peak concentrations in serum were found to be similar.