Biopharmaceutics Classification of Drugs

As mentioned in Section 6.1.2, the first attempts to quantitatively correlate the physicochemical properties of drugs with the fraction of dose absorbed were 

In parallel, the current dissolution specifications [223] are not correlated with the drug s dimensionless solubility-dose ratio 1/0, which has been shown [90] to control both the extent of dissolution as well as the mean dissolution time, MDT, which is a global kinetic parameter of drug dissolution. 

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Lennernas H and Abrahamsson B (2005) The Use of Biopharmaceutic Classification of Drugs in Drug Discovery and Development Current Status and Future Extension. J Pharm Pharmacol 57 pp 273-285. 

Lennernas H, Abrahamsson B (2005) The use of biopharmaceutic classification of drugs in drug discovery and development Current status and future extension. J Pharm Pharmacol 57 273-285. 

More mechanistic studies in humans during Phase I must be performed for better feedback to discovery and pharmaceutical development, and thereby for faster performance through the clinical phases. It was recently suggested that a biopharmaceutical classification of drug permeability coefficients and dissolution issues must be determined early in the development program for rational drug design (Amidon 1996). 

Figure 3.1 The Biopharmaceutics Classification System as defined by Amidon et al. [6]. The BCS is a classification of drug substances according to their solubility and permeability properties, in orderto stand forthe most fundamental viewofthe drug intestinal absorption process following oral administration.

I 6 H-bonding Parameterization in Quantitative Structure-Activity Relationships i Drug Design Tab. 6.5 Biopharmaceutics classification for 254 Drugs on the basis of HYBOT descriptors. 

Fig. 12 Illustration of the Biopharmaceutical Classification System (BCS), which classifies drug absorption potential on the basis of aqueous solubility or membrane permeability. (Copyright 2000 Saguaro Technical Press, Inc., used with permission.)...

Bioavailability depends not only on having the drug in solution, but also on the drug s permeability. A jejunal permeability of at least 2-4 x 10 4cm/s, measured in human subjects by intubation, is considered high [97]. For many drugs and other substances, this permeability corresponds to a fraction absorbed of 90% or better. Amidon et al. [97] thus proposed a Biopharmaceutics Classification System (BCS) for drugs based on the above definitions of these two parameters. Table 3 defines the BCS and includes some drugs representative of each class. 

Waiver of in vivo bioavailability and bioequivalence studies for immediate release solid oral dosage forms based on a biopharmaceutics classification system. Center for Drug Evaluation and Research, Food and Drug Administration, issued 8/2000, posted 8/31/2000. http //www.fda.gov/cder/guidance/ index, htm... 

Based on their solubility and intestinal permeability characteristics, drugs have been classified into one of four categories according to the Biopharmaceutics Classification System (BCS) proposed by Amidon et al. [49]. 

CDER Waiver of in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms based on a biopharmaceutics classification system Food and Drug Administration, 2000. 

U.S. Department of Health and Human Services Food and Drug Administration Center for Drug Evaluation and Research (CDER). Guidance for Industry Waiver of In Vivo Bioavailability and Bioequivalence Studies for Immediate Release Solid Oral Dosage Forms Based on a Biopharmaceutics Classification System. 2000. 

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