AN INVESTIGATION OF THE DOSE PROPORTIONALITY OF DEFLAZACORT PHARMACOKINETICS

The dose proportionality of deflazacort was assessed following single- dose oral administration at doses of 3, 6, and 36 mg to 24 healthy you ng adult volunteers. The active metabolite of deflazacort (21-desacety l deflazacort) was monitored in plasma using a sensitive, semi-microbo re liquid chromatographic method. C-max averaged 10.4+/-5.0, 19.8+/-7. 5, and 132.6+/-52.5 ng mL(-1) for the 3, 6, and 36 mg doses, respectiv ely. AUC(0-infinity) averaged 38.5+/-37.1, 64.9+/-20.8, and 411.7+/-14 8.5 ng h mL(-1) for the same three doses, respectively. Elimination ha lf-life ranged from 1.9+/-0.5 h at the 6 mg dose to 2.4+/-1.5 h at the 36 mg dose. Regression analyses of dose versus C-max and AUC(0-infini ty) yielded intercepts which were not significantly different from zer o (p>0.05) and slopes which were significant (p<0.05). Regression anal ysis of dose versus apparent oral clearance yielded a slope which was not significantly different from zero (p>0.05). These data indicate th at deflazacort exhibits dose-proportional pharmacokinetics.