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The Biopharmaceutics Classification System is a system to differentiate the drugs on the basis of their solubility and permeability. It is a guide for predicting the intestinal drug absorption provided by the U.S. Food and Drug Administration(). The fundamental basis for the BCS was established by Gordon Amidon, who was presented with a Distinguished Science Award at the August 2006 International Pharmaceutical Federation (FIP) congress in Salvador, Brazil. This system restricts the prediction using the parameters solubility and intestinal permeability. The solubility classification is based on a United States Pharmacopoeia (USP) aperture. The intestinal permeability classification is based on a comparison to the intravenous injection. All those factors are highly important because 85% of the most sold drugs in the United States and Europe are orally administered. ==BCS classes== According to the Biopharmaceutics Classification System, 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, bicalutamide, ezetimibe,phenytoin * * 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 criteria can be applied. *Class IV - low permeability, low solubility * * Example: hydrochlorothiazide, Bifonazole * * Those compounds have a poor bioavailability. Usually they are not well absorbed over the intestinal mucosa and a high variability is expected. The drugs are classified in BCS on the basis of following parameters: 1. Solubility 2. Permeability 3. Dissolution The class boundaries for these parameters are: 1. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Biopharmaceutics Classification System」の詳細全文を読む スポンサード リンク
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