PHRM 100 Lecture 3: PDD 3 and 4
Document Summary
Pharmaceutical stability: extent to which product retains same properties and characteristics. Chemical stability: active ingredient retains its chemical integrity and potency: degradation reactions: hydrolysis > oxidation/ photolysis. Hydrolysis is mediated by water and promoted at certain ph values: lactams, esters and amides. Oxidation: atmospheric oxygen (often trace amounts of impurities) Microbiological stability: sterility or resistance to microbiological growth. Physical instability of emulsions: coalescence, flocculation, creaming, breaking. Capsules: cracking, tackiness, mottling of coatings, hardening or softening of shell. Storage (environment and time) and handling: suboptimal storage temperature decrease stability affect therapeutic outcome. Shelf life: the time product is expected to remain within approved specifications. Rate of reaction is proportional to molar concentration of reactants to the power of number of moles of substance undergoing reaction. First order: rate depends on reactant concentration, log c= log c0 (kt)/ 2. 303, plot log concentration vs time to give linear line.
