A drug should be dissolved before it is absorbed. TRUE or FALSE
TRUE
What is Dissolution ?
The process by which a drug molecule (or ion, i.e. salts) moves from the solid phase to the liquid
phase
Low solubility of drug in the body means dissolution maybe the rate-limiting step to absorption and, thereafter,
therapeutic effect. TRUE or FALSE
TRUE
Define ‘Solutions’
Homogeneous mixtures of two or more pure substances
In a solution, the solute is dispersed uniformly throughout the solvent. TRUE or FALSE
TRUE
Molality is more accurate than Molarity. Why ?
Molality is unaffected by temperature
How does a solution form ? Use NaCl in water as an example
- NaCl is the solute, water is the solvent
- Hydrogen bonds between water molecules are disrupted (thermodynamics)
- NaCl dissociates into Na+ and Cl-
- Ion-dipole interactions form b/wn Na-OH2 and ClH2O
- This means ions are solvated by water
(water = solvent, Ions are hydrated)
If intermolecular forces b/wn solute and solvent are stronger then it is more likely that the solute will dissolve in the solvent. TRUE or FALSE
TRUE
State 4 types of intermolecular forces
1) Hydrogen bonds
2) Dipole-dipole interactions
3) Van der Waals
4) ion-dipole interactions (for ionic species)
The degree of hydrogen bonding can influence solubility in Glucose and cyclohexane. TRUE or FALSE
TRUE
Which vitamins are soluble in non-polar solvents (e.g: oils)
VIt A, D, K and E
Which vitamins are water-soluble ?
Vit B and C
How does a solution form ?
- Solvent molecules are attracted to surface ions
- Each ion is surrounded by solvent molecules
- Energy change results in solvation/hydration
e. g: NaCl (or other ionic solids) in water
