Biopharmaceutical Classification Scheme

Guidance for Industry, waiver of in vivo bioavailability and bioequivalence studies for immediate release solid oral dosage forms based on a biopharmaceutics classification scheme. Food and Drug Administration, Center for Drug Evaluation and Research, Rockville, Maryland, USA, August 2000. 

Interestingly, increasing solubility is a pharmacokinetic as well as a pharmaceutical objective. Indeed, and as made explicit in the Biopharmaceutics Classification Scheme (BCS) [24], solubility is one of the main factors influencing oral absorption and hence oral bioavailability. 

Physicochemical profiling has gained considerable importance in the last years as most companies realized that inappropriate physicochemical properties could lead to compound withdrawal later in development. The basic physicochemical parameters of interest for drugability prediction are solubility and permeability, the two components of the Biopharmaceutical Classification Scheme. However, these two fundamental parameters are in turn influenced by other physicochemical parameters worth considering, particularly in the lead optimization phase. For example, permeability is influeneed by lipophilicity (induces membrane retention) and pH (ioniz-able compounds), solubility is influenced by pH (ionizable compounds), and dissolution rate is linked to particle size, polymorphism, and wettability. 

Rapid release granulation is expected to benefit the class of compound where absorption is highly dependent on the dissolution of the drugs in the gastrointestinal tract, termed as Class II compounds under the Biopharmaceutics Classification Scheme (Table 1). 

A biopharmaceutics drug classification scheme (BDCS) for correlating in vitro drug product dissolution and in vivo bioavailabUity is based on recognizing that drug dissolution and GI permeability are the fundamental parameters controlling the rate and extent of drug absorption. The BDCS is defined as ... 

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