Biopharmaceutical Classification Flashcards
What is the salt form of a drug?
A more soluble form of the drug that readily ionises in aqueous media
How does the BCS classify drugs?
Based on solubility and permeability
What is a sink condition?
The volume of solvent required for complete dissolution
What is Overton’s Rule?
Membrane permeability of a molecule increases with its hydrophobicity
What is Lipinski’s Rule of 5?
That the lipophilicity of an orally administered drug should not exceed 100000 (LogP <5)
What are the two parameters that determine drug absorption?
Solubility and permeability
What is a class I drug?
High permeability and high solubility
What is a class II drug?
High permeability, low solubility
What is a class III drug?
Low permeability, high solubility
What is a class IV drug?
Low permeability, low solubility
What is the bioavailability of a class I drug?
Well absorbed with fast absorption rate
What is the bioavailability of a class II drug?
Bioavailability is limited by their solvation rate
What is the bioavailability of a class III drug?
Absorption is limited by permeation rate, but has fast solvation
What is the conditions for pH-solubility testing?
1 to 7.5 at 37 degrees
Why are the conditions for solubility what they are?
That is the temperature and pH of the GIT
How do we determine intestinal permeability in vivo?
By testing with humans or with animals
How do we determine intestinal permeability in vitro?
By using excised human or animal intestinal tissue
By doing experiments across epithelial cell layers
What does it mean when a drug is highly soluble in the BCS?
Highest strength dose should be soluble in 250 mL of aqueous media over a pH range of 1-7.5 at 37
Why is the graph of permeability and time not linear?
Because of the lag time (tL) required for a penetrant to establish a uniform concentration gradient within the membrane separating the donor from the receptor
What is a bio-waiver?
An exemption from conducting human bioequivalence studies for new dosage forms
What are the parameters for a bio-waiver?
Rapid and similar dissolution to a marketed formulation
High solubility
High permeability
Wide therapeutic window
