A Study Comparing the Clinical Pharmacokinetics, Pharmacodynamics, and Tolerability of Triamcinolone Acetonide HFA‐134a Metered‐Dose Inhaler and Budesonide Dry‐Powder Inhaler following Inhalation Administration

The impending phaseout of chlorofluorocarbons as propellants in pressurized metered-dose inhalers used in the treatment of asthma has resulted in the development of alternative devices to deliver drug to the pulmonary airways. These alternative devices include metered-dose inhalers using environmentally friendly hydroflurocarbon propellants and breath-actuated dry-powder inhalers. The purpose of this study was to compare the single- and multiple-dose pharmacokinetics, pharmacodynamics, and tolerability of a newly developed hydroflurocarbon formulation of triamcinolone acetonide (Azmacort® HFA 225 mcg Inhalation Aerosol) to that of the dry-powder formulation of budesonide (Pulmicort®Turbuhaler 200 mcg). This three-way crossover study used 18 normal healthy subjects each receiving a 675 mcg dose of triamcinolone acetonide, 600 mcg dose of budesonide, or placebo twice a day for 5 days. Serial plasma samples were collected after the first and last dose of test medication for pharmacokinetic analysis. Pharmacodynamics were assessed by changes in hypothalamic-pituitary-adrenal axis function as measured by 8 a.m. serum cortisol, 24-hour overnight serum cortisol AUC (0-24) , and 24-hour urinary-free cortisol after the last evening dose of test drug. Tolerability was assessed through physical examinations, vital signs, 12-lead ECG, routine clinical labs, and adverse events recording. Both compounds were systemically absorbed. However, no significant drug accumulation was noted with chronic dosing. Chronic dosing did result in a statistically significant 20% reduction in basal 24-hour serum cortisol AUC (0-24) for both compounds. There were no clinically significant abnormalities in physical examination, vital signs, 12-lead ECG, or routine clinical labs noted during the study. Overall, the study drugs were well tolerated, with adverse events characterized as mild to moderate in severity.