Aspects of Pharmacokinetic Study Design to Differentiate Between Different Orally Inhaled Drug Products
Borgstrom L, Olsson B.
Respiratory Drug Delivery 2010. Volume 1, 2010: 285-292.
Abstract:
A basic requirement for claiming bioequivalence (BE) is that the compared formulations are pharmaceutically equivalent but, in addition, there is a need to evaluate the in vivo clinical pharmacokinetics (in vivo PK) and the therapeutic effects of the formulations. In vivo PK-studies should evaluate both the local (lung) availability as well as the systemic availability of the inhaled drug. Lung availability can be estimated using two approaches; (i) measurement of plasma levels after charcoal blockage of the gastrointestinal absorption and (ii) measurement of amount of drug in the urine 30 minutes following inhalation. Because concurrent disease may change the lung geometry and lung wall properties, acutely and over time, in vivo PK BE studies should be undertaken in patient populations. Clinical effect studies are also needed in a comprehensive BE evaluation and should include two different dose levels for both formulations on the uprising part of the dose response curve to allow appropriate conclusions to be drawn.
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