As exemplified by sorbitol, some common excipients have unexpected effect on bioavailability/bioequivalence, depending on the pharmacokinetic characteristics of the drug, as well as the type and amount of the excipient present in the formulation. More research is warranted to examine other 'common' excipients that may have unintended influence on bioavailability/bioequivalence.

The closed-face cassette sampler is capable of a higher collection of airborne TDI and the technique involved is as simple and feasible as that of the open-face sampler.