Bronchoprovocation Study to Demonstrate the Pharmacodynamic Bioequivalence of Albuterol Sulfate HFA Inhalation Aerosol (E.Q. 90 mcg of Albuterol Base/Inh) of Macleods Pharmaceuticals Ltd

This is a pharmacodynamic bioequivalence bronchoprovocation study using single-dose, double-blind, double-dummy, randomized, study consisting of four study treatments (zero dose \[Placebo\], E.Q. 90 mcg Base dose of R inhalation aerosol, E.Q. 180 mcg Base dose of R inhalation aerosol, E.Q. 90 mcg Base dose of T inhalation aerosol) and four Periods (Period 1 to Period 4). Randomization procedure at Period 1 will assign any one study treatment to be administered in each Period in a cross-over manner. By the end of Period 4, a subject who completes dosing in all four Periods would have administered all four treatments in the study. The efficacy variable, post-dose PC20 obtained during each Period is the provocative concentration of the methacholine challenge agent required to reduce the FEV1 by 20% following administration of differing doses of albuterol (or placebo) by inhalation. The 20% reduction in FEV1 is determined as compared to post-saline FEV1 measured before the Placebo or Albuterol administration. The pharmacodynamic equivalence will be based on the dose-scale method of analysis of the post-dose PC20 If the 90% confidence interval for the relative bioavailability (F) falls within 67.00% -150.00% then it will be considered that pharmacodynamic equivalence is established.