Скачать или смотреть Bioavailability & Bioequivalence

Dr Chan wishes to prescribe generic medicines to his patients but is uncertain if the medicines are interchangeable with the brand products.

Let me explain from the beginning...

The area-under-the concentration- time curve (AUC) of an intravenously administerd drug is determined by the Dose/Clearance of the drug. For an orally administered drug, the AUC is determined by F*Dose/Clearance, where F is the bioavailbility of the drug. It can be measured by applying the trapezoidal rule. The sum of the trapezoids beneath the concentration-time curve will be the AUC.

Since it is the same drug being administered intraveously and orally, if we can assume the Dose and Clearance of the drug is the same, the intravenous and oral equations can be solved simultaneously, to become F = AUCoral/AUCiv.

The bioavailibilityof any drug can be affected by a variety of reasons. For a generic drug however, the main concern is whether the different formulation methods affect the bioavailability of the drug, thereby affecting safety and efficacy.

The relative bioavailability between the generic formulation and the reference proprietary product can be estimated by AUCgeneric/AUCreference product.

The European definition for bioequivalence is : "Two medicinal products are bioequivalent if they are pharmaceutically equivalent or pharmaceutical alternatives: and if their bioavailabilities after administration in the same molar dose are similar to such a degree that their effects, with respect to both efficacy and safety, will be essentially the same."

Essentially, the generic product must be interchangeable or substitutable with the proprietary product. Pharmacokinetically, the Cmax and AUC of the generic product must be between 80-125% of the proprietary product.

Generic medicines if regulated properly are as efficacious and safe as the branded drug.

For more educational materials please visit www.pharmacologytutorials.com
Edmund J.D. Lee

The background music is
PACIFIC SUN by Nicolai Heidlas Music   / nicolai-heidlas  
Creative Commons — Attribution 3.0 Unported— CC BY 3.0
http://creativecommons.org/licenses/b...
Music promoted by Audio Library    • Видео