PHARMACOKINETICS OF DIMINAZENE IN FEMALE BORAN (BOS-INDICUS) CATTLE

The disposition kinetics and bioavailability of diminazene in five hea lthy heifers were determined after single intravenous (i.v.) and intra muscular (i.m.) administration of the drug in sequence with a wash-out period between administrations of 6 weeks. Intact diminazene in plasm a, whole blood and urine samples was analysed using high-performance l iquid chromatography. Non-linear regression analysis of the i.v. and i .m. data indicated that, for either route, the plasma disappearance cu rves of diminazene were best described by triexponential equations. Th e i.v. bolus was followed by rapid and biphasic distribution with half -life values of 0.04 h and 0.58 h, V(d(ss)) was 1.91 +/- 0.42 l/kg, el imination half-life was 31.71 h while Cl averaged 1.74 +/- 0.40 ml/min /kg. Within 30 min of the i.v. dose, the erythrocyte/plasma partition ratio of diminazene was 0.30 +/- 0.15. Diminazene was rapidly absorbed following i.m. administration; t1/2k(a) was 0.60 h. C(max), 4.68 +/- 1.12 mug/ml, was attained in 10-15 min and systemic availability was 1 02.42 +/- 7.25%. The half-life of the terminal disappearance phase was 145.48 h. About 8.26% of the i.m. dose was excreted intact in the uri ne within the first 24 h of treatment. In vitro, diminazene was bound to bovine plasma albumin to the extent of 38.01-91.10%.