Sch 21420, the 1-N-HAPA derivative of gentamicin B, has been compared to gentamicin, tobramycin and amikacin in a variety of in vitro and in vivo tests. Based on studies with a large number of sensitive and resistant bacteria, it was shown that Sch 21420 has a spectrum
and potency essentially the same as that of amikacin. Serum levels in mice, rats, and dogs are similar to those of other aminoglycosides. Sch 21420 was found to be markedly less toxic than amikacin in chronic renal function tests in rats and thus appears to have an advantageously improved therapeutic index compared to amikacin.