Tuberc Respir Dis.  1987 Sep;34(3):233-239. 10.4046/trd.1987.34.3.233.

The Effect of H2-Receptor Blocker, Ranitidine, on the Theophylline Metabolism

• KMID: 2528647
• DOI: http://doi.org/10.4046/trd.1987.34.3.233

Abstract

Because of the increased incidence of peptic ulcer disease in patients with chronic obstructive pulmonary disease (COPD), sometimes it is necessary to use H ₂-blocking agents and aminophylline at the same time. Among the H ₂-blockers, cimetidine is well known to impair the theophylline metabolism. But there are some controversies about the effect of ranitidine on the metabolism of theophylline. So we have done the pharmacokinetic studies of aminophylline with and without ranitidine on 6 normal subjects and also measured the serum aminophylline levels following the administration of ranitidine for 7 days on 9 patients with COPD. In 6 normal subjects, serum theophylline levels were measured at 1/ 2 hour, 2 hours, 4 hours, 6 hours and 8 hours after the infusion of 7 mg/ kg of aminophylline. The serum theophylline levels were measured again after the subjects took 300 mg/ day ranitidine for 4- 7 days. There were no significant differences in serum theophylline levels between pre. and post-ranitidine administration. Also no significant differences were found with and without ranitidine in β (elimination rate constant: 0.0803±0.0143 hr^- 1 vs 0.0737±0.0125 hr^-), T1/ 2 (elimination half life: 8.91±1.79 hours vs 9. 64±1.64 hours), A.U.C (area under the time concentration cuπe: 184.37± 32.07 ug/ ml / hr vs 189 .67±22.77 μg/ml/hr) ， M.R.T. (mean residence time: 11.88±2.85 hours vs 12.88± 2.78 hours), V d (volume of distribution: 0.49±0.06 L/ kg vs 0.52±0.08 L/ kg) and c.L. (clearance: 2.52±0.40 L/ kg vs 2.43±0.29 L/ kg). In 9 patients with COPD, serum trough levels of theophylline were compared before and after taking ranitidine for 7 days. Again no significant effects of ranitidine on the theophylline level were found (10.5±2.6 ng/ ml vs 10.0±2.5 ng/ ml). Our data suggest that ranitidine does not have significant effect on the aminophylline metabolism