Gamma scintigraphy: an in vivo technique for assessing the equivalence of inhaled products

Classical bioequivalence testing, based upon equal rates and extents of drug absorption, is inappropriate for showing equivalence of products containing inhaled asthma drugs, which act directly on the airway surface. The non-invasive imaging technique of gamma scintigraphy gives a measure of local b...

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Bibliographic Details
Published in:International Journal of Pharmaceutics 1998-08, Vol.170 (1), p.1-9
Main Authors: Newman, S.P., Wilding, I.R.
Format: Article
Language:English
Subjects:
Analysis
Bioequivalence
Biological and medical sciences
Drug delivery
Gamma scintigraphy
General pharmacology
Inhalers
Medical sciences
Pharmaceutical technology. Pharmaceutical industry
Pharmacology. Drug treatments
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Summary:Classical bioequivalence testing, based upon equal rates and extents of drug absorption, is inappropriate for showing equivalence of products containing inhaled asthma drugs, which act directly on the airway surface. The non-invasive imaging technique of gamma scintigraphy gives a measure of local bioavailability at the site of action in the lungs, and lung deposition data are strongly correlated with clinical response to inhaled asthma drugs. Therefore if two inhaler products have the same whole lung deposition and the same regional airway deposition pattern, they will be therapeutically equivalent. For assessing the equivalence of inhaled asthma medications, gamma scintigraphy determines in vivo drug delivery more precisely than in vitro testing, and is more incisive than clinical response studies. The approach requires fewer patients than clinical response studies, providing appropriate data in less time, and with the guarantee of strong endpoints. Gamma scintigraphy should therefore become a recognized technique by the regulatory authorities for assessing pulmonary bioequivalence of inhaled products.
ISSN:0378-5173
1873-3476
DOI:10.1016/S0378-5173(98)00029-5