Absorption, distribution, and excretion of Imidocarb dipropionate (3,3'-bis-(2-imidazolin-2-yl) carbanilide) in sheep

Abstract

Spectrophotometric and thin-layer chromatographic methods for quantitative and qualitative determination of imidocarb in biologic specimens are described. Imidocarb was extracted under basic conditions from plasma, urine, milk, bile and homogenized tissue samples into organic solvents. Following extraction and concentration in 0.82 N HCl, the drug can be qualitatively identified by thin-layer chromatography and spectrophotometry. The detection limit for estimation of pure imidocarb in aqueous solution by spectrophotometry is equivalent to a concentration of 1.0 μg/ml in plasma and other body fluids and 5.0 μg/Gm in tissues. With thin-layer chromatography, the minimum detection level is 0.21 μg. Following intravenous injection of imidocarb dipropionate (2.0 mg/kg of body weight) into sheep, the high initial plasma concentration of 10.8 μg/ml fell very rapidly to 1.9 μg/ml in 1 hour, and was less than 1 μg/ml in 4 hours post injection. When 4.5 mg/kg of body weight of imidocarb was injected intramuscularly into sheep, peak plasma concentrations of 7.9 μg/ml were attained within 4 hours. This was followed by a rapid decline within the next 2 hours to 4.6 μg/ml, and then by a very slow decline of several weeks duration. Trace amounts were still present in the plasma 4 weeks after treatment. The drug was bound to plasma proteins to the extent of 21-53%, and the apparent volume of distribution was slightly higher than the total body water. ...