Solution Flashcards
What is a solution
Molecules of solute and solvent
What is a suspension
Solid particles and molecules of continuous phase
What is an emulsion
One liquid dispersed in another liquid
Advantages of liquids
Different doses easily administered
Easily swallowed for children or elderly
Easier to manufacture
Rapid action (intravenous route or oral)
Easy to inject
Easy to apply
Disadvantage of liquids
Bulky and inconvenient
Stability of ingredients is poor
Media for microbial growth
Accurate dosing more difficult (overdosing/ underdosing)
Taste of drug more pronounced
Examples of solutions
Mixtures
Ear drops
Eye drops
Cough syrups
Nasal products
Mouthwashe
What is the drug dissolution process
Solute molecule is removed from its crystal
Cavity for the molecule is created in the solvent
Solute molecule is inserted into cavity
How can we increase drug solubility
Ph medium
Use mixed solvents
Cyclodextrins as solubilising agents
Surfactants as solubilisers
Additives
What does a surfactants self assemble to
Micelle
Effect of flocculation on sedimentation rate
Faster sedimentation rate as floc is larger
Greater sediment volume
Suspension is easy to redisperse
How are emulsifiers used to stop emulsion breaking
Absorbs quickly around the dispersed drop
Macromolecules/ polymers
Surfactants
Difference between suspension and solution
A stage when the solute can no longer dissolve is a saturated solution
Solute above the solubility ends in a suspension
Super saturation
More molecules of solute than solvent
Concentration is higher than the solubility
Ideal gas law
PV=nRT
Henry’s law
C=kP
C= conc of dissolved gas
K= constant characteristic for the gas
P= partial pressure
Factors affecting solubility
Strength of solid solid bonds
Strength of solvent solvent bonds
Interaction between solute and solvent
Bioavailability
% of drug that you administer that gets into the bloodstream
What are formulation issues needed to consider for solutions
Quality of water= needs to be pure
Solubility of drug
Ph
Sterility
Chemical stability
Aesthetic = taste smell and look
How can you manipulate solubility
Temperature
Cosolvents- affects the solvent properties of water to increase solubility
Ph- ionised form is more soluble
Salt formations
Surfactants
Complexing agents
Routes of degradation
Oxidation= oxygen
Photolysis= light
Hydrolysis= water
What are some chemical stability enhancers
Packaging to match degradation route
Buffer to maintain ph
Anti-oxidant
Reduce 02 permeation into package = glass
Light= use amber glass
