ABSTRACT

The inhaled route is the most effective way to treat asthma, COPD and other respiratory diseases. Since target directed administration is employed, plasma levels are not a good marker of bioavailability. That is why; it is not possible to demonstrate interchangeability of this kind of formulations using drug serum concentrations. In order to establish the interchangeability of inhaled bronchodilators, several methods have been proposed to demonstrate interchangeability, such as measurement of particle size, lung gamma scintigraphy, measurement of plasma and urinary concentrations. However none of these studies measure the effect of the drug. In the case of these drugs acting on airway, plasma concentrations do not reflect the effect of the drug and can be associated with systemic side effects. For all these reasons the best way to evaluate these products through clinical efficacy studies to determine bioequivalence. These studies may be bronchodilation or bronchoprotection but only bronchodilation studies evaluate directly the effect of and the duration of it, and it’s not necessary to administer a bonchoconstrictor agent. In the case of inhaled corticosteroids it’s also recommended clinical efficacy studies to determine interchangeability.

KEYWORDS

Bioequivalence, bronchodilators, inhaled corticosteroids, interchangeability, generic medicines, inhaled medicines.

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