Pharmaceutical Stability Flashcards
1
Q
What is drug stability
A
The extent to which a product retains, within specified limits and throughout its period of storage and use, the same properties and characteristics it possessed at the time of manufacture
2
Q
What factors affect drug stability
A
- temp
- moisture
- light
- oxygen
3
Q
How do we measure the quality of a drug
A
- the content of the active substance
- purity of the active substance
- te physiochemical properties of the product
- the organoleptic (how they act on organs) and aesthetic properties of the product
4
Q
What are the four modes of product degradation
A
- chemical
- physical
- microbial
- biological
5
Q
What are the five types of chemical degradation of a product
A
- hydrolysis
- oxidation
- photolysis
- isomerisation
- dimerisation/ polymerisation
6
Q
What is is hydrolysis and what drugs are likely to undergo hydrolysis degradation
A
- it is broken down in an acid or base hydrolysis reaction as it is catalysed by hydrogen ions or hydroxyl ions.
- esters, - these are broken down into alcohols and carbolysic acids .
Such as ASPRIN, COCAINE, PROCAINE, TETRACAINE - amides- these are broken down into carboxylic acids and ammonia salts or amines
Such as DIBUCAINE, CHLORAMPHENICAL SPIRONOLACTONE - lactams , GO OVERsuch as PENICILLINS, CEPHALOSPORINS, NITRAZEPAM.
7
Q
How can hydrolysis be minimised
A
- minimise the contact to moisture or remove moisture - create solid dosage forms ( desiccant- where you remove all moisture)
- adjust the pH - so that it can not be catalysed to start an acid/ base hydrolysis.
- reduce the solubility, use less soluble salts, solvents - the drug will not be hydrolysed if it is not in a solvent, a suspension and by formed such as penicillin suspensions
- alter dielectric constant by addition of non aqueous solvents - use glycerin or propylene glycol or ethanol
- form complexes- for example the addition of caffeine to benzocaine, procaine and amethocaine.
