Biopharmaceutical classification system

The biopharmaceutical classification system (English: Biopharmaceutics Classification System, BCS) classifies drugs according to their expected bioavailability . It enables a prognosis as to whether the extent and rate of absorption after oral administration are more determined by the physical properties of the drug or more by physiological factors. The concept is based on the fact that the oral bioavailability of an active ingredient is essentially determined by its solubility and its permeability .

The BCS was developed and published in the USA by Gordon Amidon in the mid-1990s and is now part of both a US FDA (Food and Drug Administration) guideline and a guideline of the European Medicines Agency for assessing the bioequivalence of drugs. Under certain conditions, pharmaceutical companies based on the BCS can justify the waiver of the otherwise mandatory implementation of in vivo studies to determine bioequivalence within the framework of the approval of generics or product line extensions (so-called biowaiver ).

Classification of drugs in BCS classes
class	solubility	Permeability	Absorption	Fabric example (s)
I.	high	high	good absorption, only controlled by the speed of gastric emptying	Metoprolol
II	low	high	absorption is controlled by the solubility and / or the rate of dissolution of the drug	Glibenclamide , ibuprofen , diclofenac
III	high	low	the absorption is independent of the physical properties of the drug	Cimetidine
IV	low	low	The rate and extent of absorption must be considered on a case-by-case basis

Explanations to the table:

↑ Solubility is rated as high if the drug can be completely dissolved in its highest therapeutic single dose in 250 milliliters of water in the physiological pH range from 1 to 8.
↑ A high permeation capacity is present when the drug is absorbed to more than 90%. In practice, the “permeability coefficient” Papp (unit: 10 ⁻⁶ cm · sec ⁻¹ ), which is determined in the CaCo-2 cell model based on the permeation through the membrane of adenocarcinoma cells , is often used for assessment . A cardboard larger than 10 is associated with an absorption of over 90%. A cardboard smaller than 0.1 means a low absorption rate.

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Amidon GL, Lennernäs H., Shah VP, Crison JR A Theoretical Basis For a Biopharmaceutics Drug Classification: The Correlation of In Vitro Drug Product Dissolution and In Vivo Bioavailability . Pharm Res 1995. Mar; 12 (3): 413-20. PMID 7617530
Waterbeemd H., Lennernäs H., Artursson P. (editors), Drug bioavailability: estimation of solubility, permeability, absorption and bioavailability , Wiley-VCH, Weinheim, Germany. 2003. ISBN 3-527-30438-X
Möller H., Potthast H. Biopharmaceutical characterization of medicinal substances and finished medicinal products . Pharm. Ztg. 144 (1999) 1640.
Announcement of the approval according to § 21 of the Medicines Act (bioavailability / bioequivalence) of December 18, 2002. BAnz. Of March 25, 2003 5296

Web links

The Biopharmaceutics Classification System (BCS) Guidance of the Food and Drug Administration , last updated April 1, 2009
Working Group on BCS and Biowaiver of the International Pharmaceutical Federation
Concept Paper on BCS-based Biowaiver of the European Medicines Agency (PDF file; 43 kB)

[1] Solubility is rated as high if the drug can be completely dissolved in its highest therapeutic single dose in 250 milliliters of water in the physiological pH range from 1 to 8.

[2] A high permeation capacity is present when the drug is absorbed to more than 90%. In practice, the “permeability coefficient” Papp (unit: 10 ⁻⁶ cm · sec ⁻¹ ), which is determined in the CaCo-2 cell model based on the permeation through the membrane of adenocarcinoma cells , is often used for assessment . A cardboard larger than 10 is associated with an absorption of over 90%. A cardboard smaller than 0.1 means a low absorption rate.