Developability Classification system (DCS):
A Develop-ability Classification System (DCS) that connects biopharmaceutical
space areas with formulation strategy He classified chemicals based on how
difficult they were to formulate for maximum oral absorption. The Class II is
divided into two categories: IIa (dissolution-limited absorption chemicals) and IIb
(dissolution-unlimited absorption compounds) (solubility limited absorption
compounds). Standard technologies could be used to create Class IIa drugs, with a
focus on particle size distribution. More difficult formulation processes, such as
solid dispersion and lipid formulations, are required for Class IIb drugs.
The revised system is designed to place a greater focus on drug development
ability. The revised system needed to consider intestinal solubility, the
compensatory nature of solubility and permeability in the small intestine, and an
estimate of the particle size required to overcome dissolution rate limited
absorption.
The BCS categorizes solubility over the Gl pHrange (pH 1.2-6.8) in simple buffer
systems. to be an under-estimation of the true in vivo solubility at the site of
absorption, as many drugshave pH-dependent solubility and the intestinal fluid
have components such asbile acids and phospholipids, which can increase
solubilization.
Biopharmaceutics Classification System (BCS):
(BCS) where molecules are classified according to their aqueous solubility and
permeability
using BCS as a comparison tool for the evaluation of permeability and solubility
properties, we can observe that there is a significant increase in the number of
Class II (poorly soluble molecules) and Class IV (poorly soluble/permeable)
molecules in clinical development compared to the distribution seen for marketed
drugs
Advantages of (DCS):
The DCS applied solubility in fasted state simulated intestinal fluid to estimate
intestinal solubility, assessed the compensatory nature of permeability and
solubility during oral absorption.
 The DCS is incorporated into a formulation strategy and, if used properly by
trained scientists, can shave two years off the drug development process.
 Uses a visual ranking to predict the factors that are critical to in vivo
performance, such as drug solubility.
 The DCS is development friendly, removing the requirement for in vivo
permeability data and relaxing the dose.
 The Class II category is split into two new categories (Class IIa and Class
IIb) to ensure the barriers to oral absorption are fully understood.
 Drug bioavailability of Class IIa drugs is limited by the rate of dissolution
 Class IIb drugs are limited by the solubility of the compound and as such,
require complex preformulation techniques (i.e., amorphous solid
dispersions
 The DCS has subsequently been updated to the Refined DCS (rDCS) which
takes into other physicochemical properties
 Useful in evaluating new drug candidates
Difference between DCS and BCS:
The main difference between of DCS to that BCS is that class 2 compounds are
subdivided into 2a (dissolution rate-limited) and 2b (solubility-limited) and this
information can be used to define strategies for formulation optimization
The permeability in DCS is a problem could be overcome by using different
permeability enhancers but their toxicity is often a limiting factor
The Relation between DCS and BCS:
The DCS was adapted from the BCS to include a more biorelevant solubility
assessment by using Fasted State Simulated Intestinal Fluid media (FaSSiF) to
estimate the extent of human absorption, a dissolution rate based on particle size
rather than dose-to-solubility ratio, and a solubility-limited absorbable dose
(SLAD) for Class 2 compounds.
According to the Biopharmaceutical Classification System (BCS), the solubility
and the permeability are the predominant factors determining the ability of drugs to
be absorbed in the Gastrointestinal (GI) tract and thus impacting the oral
bioavailability.