COMPARATIVE PHARMACOKINETICS OF DIMINAZENE IN NONINFECTED BORAN (BOS-INDICUS) CATTLE AND BORAN CATTLE INFECTED WITH TRYPANOSOMA-CONGOLENSE

The pharmacokinetics of diminazene in five female Boran (Bos indicus) cattle before and then during acute and chronic phases of experimental infections with Trypanosoma congolense were investigated. A 7.0% (wt/ vol) solution of diminazene aceturate (Berenil) was used in all three phases of the study and administered as a single intramuscular dose of 3.5 mg of diminazene base per kg of body weight. There were no signif icant differences between the values of pharmacokinetic parameters for the noninfected cattle and the values for cattle with a chronic T. co ngolense infection. However, the maximum concentration of the drug in plasma during the acute phase of infection (8.25 +/- 1.72 mug/ml) was significantly (P < 0.01) greater than that during chronic infection (5 .04 +/- 0.26 mug/ml) and that in the noninfected state (4.76 +/- 0.76 mug/ml). Similarly, the time to maximum concentration of the drug in p lasma when diminazene was administered during the acute phase of infec tion (18.00 +/- 6.71 min) was significantly (P < 0.02) shorter than th at for noninfected cattle (36.00 +/- 8.22 min) and that during chronic infection (33.75 +/- 7.50 min). The volume of distribution at steady state during acute infection (1.01 +/- 0.31 liter/kg) was significantl y (P < 0.01) smaller than that in the noninfected state (1.37 +/-0.17 liter/kg) and that in chronic infection (1.51 +/- 0.24 liter/kg). Eigh t hours after the drug had been administered, the concentration-time d ata profiles for each of the three study phases were very similar. Mea n concentrations of diminazene in plasma 48 h after administration of the drug were 0.43 +/- 0.07 mug/ml in noninfected cattle, 0.43 +/- 0.1 1 mug/ml during the acute phase of trypanosome infection, and 0.44 +/- 0.09 mug/ml during the chronic phase of the infection. Results of the present study indicate that the area under the concentration-time cur ve for diminazene in trypanosome-infected cattle did not differ signif icantly from that for noninfected cattle. It, therefore, appears that the total amount of diminazene attained and maintained in the plasma o f cattle is not significantly altered during infection with T. congole nse.