Biopharmaceutics Classification System

Encyclopedia : B : BI : BIO : Biopharmaceutics Classification System

For other uses of the abbreviation BCS, please see BCS (disambiguation).

This system is a guidance for predicting the intestinal drug absorption provided by the U.S. Food and Drug Administration[link]. This system allows to restrict the prediction using the parameters solubility and intestinal permeability. The solubility classification is based on a United States Pharmacopoeia (USP) apperature. The intestinal permeability classification is based on a comparison to the intravenous injection. All those factors are highly important, since 85% of the most sold drugs in the USA and Europe are orally administered.

According to the Biopharmaceutics Classification System (BCS (disambiguation)), drug substances are classified as follows:

Class I - High Permeability, High Solubility
* Example: Metoprolol
* Those compounds are well absorbed and their absorption rate is usually higher than excretion.
Class II - High Permeability, Low Solubility
* Example: Glibenclamide
* The bioavailability of those products is limited by their solvation rate. A correlation between the in vivo bioavailability and the in vitro solvation can be found.
Class III - Low Permeability, High Solubility
* Example: Cimetidine
* The absorption is limited by the permeation rate but the drug is solvated very fast. If the formulation does not change the permeability or gastro-intestinal duration time, then class I criterias can be applied.
Class IV - Low Permeability, Low Solubility
* Example: Hydrochlorothiazide
* Those compounds have a poor bioavailability. Usually they are not good absorbed over the intestinal mucosa and a high variability is expected.

References

H. Waterbeemd, H. Lennernäs, P. Artursson (editors), Drug bioavailability: estimation of solubility, permeability, absorption and bioavailability, Wiley-VCH, Weinheim, Germany, 2003. ISBN 3-527-30438-X

From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.