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Biopharmaceutics Classification System

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

The Biopharmaceutics Classification System is a guidance for predicting the intestinal drug absorption provided by the U.S. Food and Drug Administration [1]. 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.[citation needed]

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
  • 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
    • Those compounds have a poor bioavailability. Usually they are not well absorbed over the intestinal mucosa and a high variability is expected.

See also


  • 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
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Biopharmaceutics_Classification_System". A list of authors is available in Wikipedia.
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