Aminoglycosides are derivatives of naturally occurring organisms and several aminoglycosides have been introduced for clinical use since the discovery of streptomycin in 1947. Amikacin, gentamicin, kanamycin, netilmicin, neomycin, streptomycin, paromomycin, and tobramycin are currently approved by the FDA for use in the United States. Among these, amikacin, gentamicin, and tobramycin are most frequently used. Because of the availability of less toxic agents, aminoglycosides have been used less often in recent years (Fig. 9.1).