Budesonide administered using chlorofluorocarbon and hydrofluoroalkane pressurized metered-dose inhalers: pharmacokinetics, pharmacodynamics and clinical equivalence.

OBJECTIVE: The traditional chlorofluorocarbon (CFC) propellants used in pressurized metered-dose inhalers (pMDIs) have unacceptable environmental effects and are being replaced by alternatives such as hydrofluoroalkanes (HFAs). However, there is a need to ensure that pMDIs with these novel propellants are as effective and safe as their older counterparts.

MATERIALS AND METHODS: Single-dose pharmacokinetic and multiple high-dose Phase I studies in healthy volunteers and randomized, controlled 12-week Phase III clinical trials in children, adolescents and adults with mild-to-moderate asthma have been performed to compare the efficacy and safety of HFA-based budesonide inhaler therapy with the traditional CFC-based pMDI.

RESULTS: The pharmacokinetic study in 40 persons showed comparable characteristics of CFC and HFApMDIs, with good dose-proportionality, at doses of 400, 800 and 1,600 microg. The high-dosage (1,600 microg/day) study in 48 subjects showed both inhaler types to be similar in terms of effects on hypothalamic-pituitary-adrenal axis function over 4 weeks. The pediatric clinical study involved 159 children and showed noninferiority of the HFA pMDI in terms of 12-week change in forced expiratory volume in 1 sec, other spirometric parameters and symptomatic measures. The adolescent/adult study in 321 subjects also showed similarity between the two formulations, in terms of 12-week primary endpoint (changes in morning peak expiratory flow rates) and other lung function and symptom measures. Both formulations were well-tolerated, with no safety issues being identified for the novel HFA inhaler in any study.

CONCLUSION: Budesonide HFA pMDI is pharmacokinetically and clinically comparable to the traditional CFC-based inhaler, with similar safety profile.