Enhanced intestinal reabsorption due to reduced metabolism of ceftriaxone

Abstract

The polyherbal drug (Fibrosin(R)) is often used as supportive therapy with intramuscular ceftriaxone injection for treatment of mastitis. A single dose of ceftriaxone at 50 mg kg-1 was administered intramuscularly in six healthy lactating goats and a single oral dose of Fibrosin(R) (1.9 gm) was given 1 hr prior to intramuscular ceftriaxone injection to study disposition of ceftriaxone. Plasma and urine samples were collected at predetermined time schedule and ceftriaxone/ceftizoxime was extracted and analyzed by HPLC. Ceftriaxone persisted for 3 hr in plasma of fibrosin treated healthy lactating goats. Mean t[1/2] K (distribution half life) following absorption phase and t[1/2] K'(elimination half life) following intestinal re-absorption phase were respectively, 0.091 {+/-} 0.01 and 0.43 {+/-} 0.03 hr with a re-absorption half life (t[1/2]Ka') of 0.18 {+/-} 0.003 hr.Ceftriaxone at a lower concentration (67.91 {+/-} 9.42 g ml-1) was recovered at 24 hr post dosing from urine. This is the first report of pharmacokinetic interaction of intramuscular ceftriaxone injection and the oral polyherbal drug (which was found to be a cytochrome P450 inhibitor).