Flashcards in Oral (Solutions) Deck (13)
Advantages of oral solutions: (3)
fast onset of action
easy to swallow and easy to manufacture
Disadvantages of oral solutions: (3)
increased drug instability compared to in solid state
packaging costs higher
many drugs are poorly soluble in water
Oral solutions must be... (4)
at physiological pH
Most common solvent is water, why?
lack of toxicity
purified water is used - produced by distillation
What can be added to drugs to make them more water soluble?
co-solvents e.g. ethanol, glycerol
Excipients in solutions: (5)
flavouring, colouring agents
Factors effecting chemical degradation: (4)
How to enhance solution stability? (3)
package in containers that reduce light transmission
formulate at suitable pH
How does pH affect solubility?
Ions are more water soluble than neutral molecules
alter pH can increase drug ionisation which increases drug solubility
Weakly acidic drugs are ionised when...
solvent pH increases
Lower solvent pH increases ionisation of...
weakly basic drugs
When are co-solvents used?
For non-ionic drugs where solubility cannot be adjusted by pH control
like dissolves like when choosing them