Depression of cardiac function by streptomycin and other antimicrobial agents

Signs of toxicity of the eighth cranial nerve in a patient receiving streptomycin who also had persistent hypotension after cardiac surgery led to investigation of the effects of streptomycin and other antibiotic agents on cardiac function. In 18 open chest dogs, there was a dose-dependent depression of cardiovascular function as a result of the intravenous administration of streptomycin in doses of 2.5, 10 and 40 mg/kg. Similar depressions were demonstrated after administration of tetracycline, kanamycin, vancomycin, erythromycin and colymycin. In 4 intact dogs given streptomycin, 2 g intramuscularly, cardiac output decreased 26 percent and mean arterial pressure decreased 22 percent 1 hour after administration. The average level of streptomycin in the blood at 1 hour was 35 μg/ml, within the usual therapeutic range for patients. In the isolated perfused cat heart, streptomycin, tetracycline, kanamycin, vancomycin and chloramphenicol caused a profound decrease in contractile force. These data should not be extrapolated directly to clinical situations since most of the experiments did not parallel precisely the usual form of antibiotic administration. In the presence of infection, antibiotic drugs are among the most effective agents available. However, the physician must be aware of the potential for cardiac depression, especially in patients with an already compromised cardiac status or with impaired renal function.