PHARMACOKINETICS OF TRIAMCINOLONE ACETONIDE AFTER INTRAVENOUS, ORAL, AND INHALED ADMINISTRATION

The pharmacokinetics of triamcinolone acetonide were studied after int ravenous (2 mg), oral (5 mg), and inhaled (2 mg) administration. Triam cinolone acetonide concentrations were measured in plasma by high-perf ormance liquid chromatography/radioimmunoassay. After intravenous admi nistration, triamcinolone acetonide was eliminated with a total body c learance of 37 L/h and a half-life of 2.0 hours. The Volume of distrib ution was 103 L, and oral bioavailability averaged 23%. Absorption was rapid, achieving maximum triamcinolone acetonide levels of 10.5 ng/mL after 1 hour. After inhalation, bioavailability averaged 22% with max imum levels of 2.0 ng/mL observed after 2.1 hours. The resulting syste mic levels for all three treatments caused a significant decrease in t he number of lymphocytes in blood.