Biopharmaceutics classification system (BCS Classification)
The Four BCS Classes
- Class 1: High solubility and High permeability.
- Drugs in this class dissolve rapidly in the gastrointestinal tract and are easily absorbed into the bloodstream. They are not significantly affected by dissolution rate or permeability issues, making them ideal candidates for biowaivers.
- Class 2: Low solubility and High permeability.
- Drugs in this class are well-absorbed once dissolved, but their absorption is limited by their poor solubility. Strategies like particle size reduction, salt formation, or use of solubility enhancers are often needed to improve their dissolution.
- Class 3: High solubility and Low permeability.
- These drugs dissolve easily but face challenges crossing biological membranes due to their low permeability. Their absorption is limited by their transport through the intestinal wall.
- Class 4: Low solubility and Low permeability.
- Drugs in this class exhibit poor solubility and permeability, making them the most challenging for formulation and absorption. Their bioavailability is typically poor, requiring advanced formulation strategies like nanoparticles or liposomes
