Pharmacopoeial testing Flashcards
what are the official pharmacopoeia tests?
unifromity of weight
uniformity of drug content
disintegration test
dissolution rate
friability
what is the uniformity of weight test?
to ensure a constant dose of drug between each tablet
two separate tests:
weight uniformity
content uniformity
what is dissolution?
the process by which a solid becomes a solute forming a solution
what is the purpose of dissolution testing?
‘assessment of production quality
assessment of bioequivalence
Prediction of in-vivo availability
Optimisation of therapeutic effectiveness during product development’
what is the Whitney-Noyes equation?
dW/dt = k (Cs-C)
where k=DA/h
what is rate-limited dissolution
‘When dissolution is significantly slower than absorption than the drug absorption’
what happens if the drug is the greater part of the tablet?
then change in tablet weight changes active ingredient
what happens if the drug is potent?
then excipients form make up most of the weight then bad correlation between tablet weight and active ingredient
methods for testing weight variations in tablets?
weigh 20 tablets that were selected randomly or determine average weight of 20 tablets
how is uniformity of drug content tested?
30 drugs weighed
10 assayed
tablets pass if 9/10 are in the range
what is intrinsic dissolution rate described by?
dW/dt1 = kCs
what is sink conditions?
where C in intrinsic dissolution is assumed to be 0
what indicates no problems with dissolution rate?
if greater than 1 mg.min^-1.cm^-2
then no problems
if less than 0.1 mg.min-1.cm-2 then problem
why is pure water not used for dissolution testing?
pH of pure water cant be controlled so isn’t used
what do the properties of solvent that tablet dissolves in have to be like?
can’t be too different than physiological conditions
