Orally administered ranitidine plasma concentrations before and after biliopancreatic diversion in morbidly obese patients

Background: Patients undergoing biliopancreatic diversion (BPD) may develop gastric ulcers, particularly within the first postoperative year. The prophylactic use of antisecretory compounds at the usual therapeutic doses, mainly conventional H-2-receptor antagonists such as ranitidine, may reduce the incidence of this complication, which occurs in similar to 5% of patients after BPD. Methods: The authors measured the plasma concentrations of ranitidine (300 mg orally) in obese patients, before and 8 months after BPD, and in control subjects of normal weight. The study included 11 obese patients undergoing BPD (age 45 +/- 14 years; preoperative and postoperative weights 124 +/- 21 and 92 +/- 11 kg) and 10 normal-weight subjects (age 37 +/- 13 years, weight 67 +/- 9 kg). Results: Postoperative ranitidine plasma concentrations showed only minor differences from preoperative levels, with slightly higher maximum concentrations occurring sooner. The mean area under the curve was on the average 30% higher than preoperatively. All parameters, however, were similar to those in control subjects. Conclusions: BPD per se does not greatly affect the pharmacokinetic behavior of ranitidine, and therefore a conventional dosage regimen appears adequate for the prophylaxis and therapy of gastric ulcers associated with this operation.