• eg amikacin, gentamicin, tobramycin, kanamycin, neomycin, netilmicin
• composed of two or more amino acids connected by a glycoside linkage; have a positive charges (polycation) cannot readily cross membranes poorly absorbed from GI tract
• poorly absorbed by GI tract – give IV or IM
• rapidly excreted by kidney
• narrow spectrum - indicated for use against gram negative bacilli; mainly used parenterally for serious gram negative aerobic bacilli
• act by binding to the 30S subunit of ribosomes incorrect amino acid sequences/synthesis abnormal protein produced.
• resistance can develop due to bacterial production of enzymes that inactivate aminoglycosides
• adverse effects – inner ear damage; renal toxicity