Penetration of moxalactam and cefazolin into atrial appendage after simultaneous intramuscular or intravenous administration.

This study compared the penetration of moxalactam and cefazolin into the human atrial appendage after simultaneous administration of both drugs by two routes. Nineteen adult patients scheduled for coronary vein bypass surgery randomly received 10 mg of moxalactam and cefazolin per kg by either the intramuscular or intravenous (bolus) route on administration of anesthesia. Concentrations of cefazolin in serum were significantly greater than concentrations of moxalactam at all times for both routes of administration. There were no significant differences, however, in the concentration of these drugs in atrial appendages, although concentrations of both agents administered intravenously were significantly greater than of drugs administered intramuscularly. (19.3 +/- 10.3 and 21.0 +/- 11.0 micrograms intravenously versus 8.3 +/- 3.6 and 10.1 +/- 3.2 micrograms/g intramuscularly for moxalactam and cefazolin, respectively).