Ｒａｎｉｔｉｄｉｎｅ注射液の１日１００ｍｇ点滴静注時および１日３００ｍｇ点滴静注時における安全性ならびに薬物動態の検討

Abstract

The pharmacokinetics and safety of ranitidine injection, a histamine H2-receptor antagonist, were studied in 7 healthy male volunteers. The study was carried out by an intravenous (iv) drip infusion of ranitidine of 100mg for 1hr, given on a once daily schedule and on a thrice daily schedule at the same speed.The ranitidine plasma concentration time curve after completion of the iv drip infusion was examined by the two compartment model. Its Cmax was about 1, 760ng·ml-1.In the ranitidine iv drip infusion of 300mg daily, the ranitidine plasma concentration time curve was well in agreement with the actual measured values after the first and second administrations. We surmise that there is no accumulation of ranitidine in this administration method, because the Cmax and the elimination curve after the third dose were similar to those after the first and the second doses.The cummulative urinary excretion rate of unchanged ranitidine as measured up to 24hr after the iv drip infusion of 100mg was about 89%.Although the gastrin, secretin, and prolactin levels in plasma showed somewhat irregular fluctuation, in comparison with the preadministration value they were not affected by ranitidine.No abnormality attributable to ranitidine was noted in blood pressures, pulse, or clinical laboratory findings.