Ranitidine improves postoperative suppression of antibody response to preoperative vaccination.

The effect of the histamine-2 receptor antagonist ranitidine (100 mg intravenously every 12 hours for 72 hours) on postoperative serum antibody responses to preoperative immunization with six limit of flocculation tetanus toxoid and six limit of flocculation diphtheria toxoid was assessed in a double-blind, placebo-controlled randomized study in 26 patients undergoing major abdominal surgery. The preoperative antitetanus antibody level was less than 0.1 IU/ml in all patients, and they were inoculated with both antigens 48 hours before surgery. Serum samples for analysis of antitetanus toxoid and antidiphtheria toxoid were drawn before skin incision and on postoperative days 1, 3, 5, 7, 10, 14, 21, and 28. Ranitidine significantly increased the postoperative antibody response to tetanus toxoid, (p less than 0.01) and insignificantly increased that to diphtheria toxoid vaccination (p less than 0.2) compared with placebo.