Drug Solubility 2 Flashcards
Co-solvents
Substances added to a primary solvent to increase solubility of a poorly-water soluble drug
Surfactant - hydrophilic + hydrophobic
- Reduces interfacial tension
- Increases drug solubilisation in water
Critical Micelle Concentration
the concentration of lipid required for micelle formation
Surfactant - CMC
- above CMC, surfactant forms micelle and encapsulates drug in hydrophobic core
- enhances solubility of drug in solution
What kind of surfactant is better for drug solubilisation?
Ionic surfactants, due to ionic exchange
What kind of surfactants can dispersed self-assembled amphillic molecules form?
- Surfactants with hydrophilic core and hydrophobic layers
- Can load both water soluble and insoluble drug
- Changes pharmacokinetics/dynamics
Surfactant toxicity
Ionic surfactants are more toxic than non-ionic ones
Molecular complexation - cyclodextrins
- Modified starches
- Ring is cylindrical with hydrophilic outer layer and hydrophobic interior
- Appropriately sized lipophilic molecules may be housed in central portion
What kinds of rings can be formed with cyclodextrins?
Alpha, beta and gamma
Alpha Rings
6 units
Beta rings
7 units
Gamma rings
8 units
Particle size reduction
- Increases surface area, increases dissolution rate
- Higher concentration at point of absorption
Preparation for particle size reduction
Top-down approach via nanomilling, stabilised with anti-crystallisation excipients
Solid dispersion - Amorphous
- Drug lattice energy = 0
- Enhanced surface area
- Enhanced hygroscopicity
