The penetration of cefonicid and cefazolin into cardiac tissue was compared after a single 30-mg/kg dose in 30 patients undergoing aortocoronary artery bypass graft surgery. Samples of the right atrial appendage, pericardial fluid, and serum were obtained at various times and assayed for drug content. The concentrations of cefonicid in serum and the atrial appendage were at least twice those observed for cefazolin at a given time after a dose. The mean (± standard deviation) atrial appendage-serum ratio was 0.47 ± 0.14 for cefonicid and 0.34 ± 0.06 for cefazolin (P < 0.005). Pericardial Cefonicid is a new cephalosporin with an antimicrobial spectrum similar to that of cefamandole except that it is less active against S. aureus and S. epidermidis. Cefonicid is excreted slowly by the kidneys, with a serum elimination half-life of ca. 4 h. High binding to serum proteins (96 to 98%) results in high concentrations in serum but also reduced the in vitro activity of this agent (6, 7). The high and prolonged concentrations in serum achieved after a single dose may allow for single-dose prophylaxis of infection during certain surgical procedures. In view of the pharmacokinetic properties of cefonicid and the potential usefulness of this agent in surgical prophylaxis, we compared the concentrations of cefonicid and cefazolin in serum, the right atrial appendage, and pericardial fluid of patients undergoing coronary artery bypass graft surgery.( the following were excluded from entry: total body weight (TBW) greater than lean body weight, +/-40%; renal dysfunction (serum creatinine greater than 1.5 mg/dl); history of a significant hypersensitivity reaction to a betalactam antibiotic; requirement for circulatory support (i.e., use of an intro-aortic balloon pump); or inability or refusal to give informed consent. There were two women in the cefonicid group and three women in the cefazolin group. The mean (+ standard deviation) total and ideal weights in the cefonicid group were 70 ± 11 and 66 ± 9 kg, respectively; in the cefazolin group, these weights were 75 ± 10 and 85 ± 10 kg, respectively. The mean preoperative serum creatinine was 1.0 ± 0.2 in the cefonicid group and 1.1 ± 0.2 in the cefazolin group. Each patient underwent a prestudy physical examination, gave a complete medical history, and had the following laboratory tests performed: complete blood count, blood urea nitrogen, serum creatinine, serum bilirubin, serum glutamic-oxaloacetic transaminase, and urinalysis. All of these tests were within the normal range in all patients.Dosing and sample collection. Patients were randomly distributed so as to receive a single 30-mg/kg TBW dose of either cefonicid or cefazolin intravenously over 5 min before surgery. Additional antimicrobial agents were withheld until after the collection of serum and tissue samples. One to three serum samples were collected from each patient during surgery before cardiopulmonary bypass. Blood samples were centrifuged at 3,250 x g for 10 min, and the serum was harvested. Pericardial fluid ...