Pharmacokinetics of triamcinolone acetonide and its phosphate ester

Triamcinolone acetonide in the form of its phosphate ester was given intravenously in two different doses (10 mg/kg and 80 mg). Plasma levels of the ester and triamcinolone acetonide were measured and pharmacokinetic parameters were calculated. The pharmacokinetics both of the phosphate and the free alcohol were dose-dependent. No unchanged ester was found in the urine, indicating complete conversion of the pro-drug. Triamcinolone was not a major metabolite of triamcinolone acetonide in humans. Renal clearance was low and independent of the dose. Only about 1% of the dose was found in the urine as triamcinolone acetonide.