Gentamicin and tobramycin are the members of this class in common use here. They have been used for decades, are only available in parenteral (IV and IM) form and are the most toxic of all regularly used antibiotics necessitating close monitoring of dosing. Nephrotoxicity and oto/vestibular toxicity can be serious.
Despite the shortcomings, they are still very useful in the therapy of infections due to Gram negative bacilli that are resistant to other agents. They are also indicated in the therapy of endocarditis caused by Streptococci and Enterococci as a “synergistic” addition to penicillins or vancomycin.