FAMOTIDINE PHARMACOKINETICS IN PATIENTS UNDERGOING CARDIAC-SURGERY

In order to study the pharmacokinetics of famotidine in cardiac surgery patients, we administered famotidine 20mg by intravenous injection at the beginning of surgery and 12 hours after surgery in 8 patients undergoing elective cardiac surgery with cardiopulmonary bypass. Total body clearance, volume of distribution, and elimination half-life were calculated using noncompartmental analysis and compared with published normal parameters (control) using a 2-tailed, 1-sample t-test. Intra- and postoperative clearances were 2.93 +/- 1.06 and 3.18 +/- 1.06 ml/min/kg, respectively, which were more than 50% less than the control value (6.07 ml/min/kg; p<0.0005). The volume of distribution (1.0 L/kg) was unaltered during the study and did not differ from the control value (1.19 L/kg; p>0.08). Intra- and postoperative half-lives were 4.52 +/- 2.21 hours and 4.27 +/- 1.58 hours, respectively, which were more than 50% longer than control (2.92 hours; p<0.03). Famotidine pharmacokinetics are significantly altered during cardiac surgery with cardiopulmonary bypass, and these changes persist for up to 24 hours after surgery.