Regulatory respiratory data refinement with reduced animal usage

Measurement of PP-HOP in a stand-alone safety pharmacology study in conjunction with HOP assessment conducted as part of a toxicology study, represents an improved respiratory testing strategy for inhaled drugs. For compounds administered by other routes, we conclude that use of WBP using a crossover dosing design is a suitable alternative to parallel dosing groups, with a significant reduction in animal numbers and no loss of statistical power.