Biopharmaceutics Classification System
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2008-06-21T10:37:52Z
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{{for|other uses of the abbreviation '''BCS'''|BCS (disambiguation)}}
The '''Biopharmaceutics Classification System''' is a guidance for predicting the [[gastrointestinal tract|intestinal]] [[drug]] absorption provided by the [[U.S. Food and Drug Administration ]][http://www.fda.gov/]. The fundamental basis for the BCS was established by Dr. Gordon Amidon who was presented with a Distinguished Science Award at the August 2006 International Pharmaceutical Federation (FIP) congress in Salvador, Brazil.{{Fact|date=February 2007}}
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 [[Route of administration|intravenous injection]]. All those factors are highly important, since 85% of the most sold drugs in the [[USA]] and [[Europe]] are [[route of administration|orally administered]].
According to the Biopharmaceutics Classification System ([[BCS (disambiguation)]]), drug substances are classified as follows:
*'''Class I - High [[intestinal permeability|Permeability]], High [[Solubility]] '''
** Example: [[Metoprolol]]
** Those compounds are well absorbed and their absorption rate is usually higher than excretion.
*'''Class II - High [[intestinal permeability|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 [[intestinal permeability|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 criteria can be applied.
*'''Class IV - Low [[intestinal permeability|Permeability]], Low [[Solubility]] '''
** Example: [[Hydrochlorothiazide]]
** Those compounds have a poor [[bioavailability]]. Usually they are not well absorbed over the intestinal mucosa and a high variability is expected.
==See also==
*[[ADME]]
**[[Partition coefficient]]
**[[Bioavailability]]
**[[Drug metabolism]]
**[[First pass effect]]
*[[Polar surface area]]
==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
==External links==
* [http://www.fda.gov/cder/OPS/BCS_guidance.htm BCS guidance] of the [[U.S. Food and Drug Administration]]
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[[Category:Pharmacology]]
[[Category:Pharmacy]]