In critically ill patients, who are likely to have expanded volumes of distribution and who are given higher initial doses, target peak serum levels are 16 to 24 mcg / mL for gentamicin (33.44 to 50.16 micromol / L) and tobramycin (34.22 to 51.34 micromol / L) and 56 to 64 mcg / mL (95.65 to 109.31 micromol / L) for amikacin.