Comparative bioavailability of two hydrofluoroalkane formulations of formoterol fumarate both delivered by pressurised metered dose inhaler.

A randomised, open-label, single dose, four-period crossover study was performed in healthy male human subjects to compare the pharmacokinetics of formoterol fumarate (CAS 43229-80-7) after inhalation from two different hydrofluoroalkane (HFA) pressurised metered dose inhaler (pMDI) formulations at two dose levels, 12 and 24 microg. This is the first study which has evaluated two HFA formulations of formoterol. Fourteen subjects were randomised, of which 13 completed the study. Each subject received in separate periods a single dose of 12 microg or 24 microg of each formulation. Blood samples for determination of formoterol plasma concentrations were taken pre-administration of study treatments and subsequently at 2, 5, 10, 20, 30, 45, 60, 90 min and 2, 3, 4, 6, 8, 12, 24 and 36 h post-administration of the study treatments. The pharmacokinetic profiles of both the formulations were similar in shape and a dose-related increase in formoterol plasma concentration was seen at all time points for both the test and reference formoterol HFA formulations between the dose levels 12 microg and 24 microg. Overall, the findings indicate that treatment with the test formoterol HFA preparation has a lung absorption pattern and systemic exposure comparable to the already licensed reference formoterol HFA preparation.