Cephradine and cefazolin plasma levels during cardiac surgery

A prospective, randomized, double-blind study was carried out to evaluate two prophylactic regimes in patients undergoing cardiac surgery with cardiopulmonary bypass. Antibiotic plasma levels were measured in fifty consecutive adult patients undergoing valve and coronary surgery. They were divided into two comparable groups of 25 patients, each matched in age, sex, type of operation and duration of cardiopulmonary bypass. Group 1 received 1 g of cephradine with the anaesthetic premedication, 1 g in the prime of the oxygenator and 1 g every six hours during the first 72 hours of the postoperative course. Group 2 received cefazolin following the same protocol except that they received 1 g every eight hours during the postoperative course. There were no allergic or toxic reactions and no infections up to two months follow-up in both groups. Antibiotic plasma levels were significantly higher (p < 0·001) in the cefazolin group in four out of five sampling periods. Antibiotic plasma levels for group 1 versus group 2 were as follows: initial level 11·7 ± 5.2 mcg/ml vs 31 4 ± 35·4 mcg/ml. During cardiopulmonary bypass 26·6 ± 9·5 mcg/ml vs 51·7 ± 21 ·1 mcg/ml. Final levels 13·6 ± 7·0 mcg/ml vs 32·2 ± 17·8 mcg/ml. Baseline levels 2·7 ± 2·3 mcg/ml vs 6·· ± 7·7 mcg/ml and peak level 44·0 ± 16·2 mcg/ml vs 51·2 ± 23·4 mcg/ml (NS). The results of this study demonstrate that cefazolin achieved significantly higher plasma levels during the different phases of the operation and early postoperative period. Also, cefazolin and cephradine levels are above the minimal inhibitory concentrations for the gram positive and gram negative susceptible bacteria, except for the basal levels obtained by cephradine. The favourable pharmacokinetic characteristics of cefazolin, makes it a good choice for prophylactic use during cardiac surgery.