Question & Answer Section

Q We have the following situation: a product releases about 90% of label claim in 7 min in pH 6.8 phosphate buffer, about 40% of label claim in 60 min in 0.1 N hydrochloric acid, and about 50% of label claim in 7 min and about 90% in 60 min in pH 4.6 acetate buffer. Which of these media is the most appropriate for this formulation?
A The discrimination power of the dissolution test needs to be considered when selecting the most appropriate dissolution medium. Fast dissolution is not discriminative enough and is appropriate only for drug substances that are classified as BCS I (highly soluble and highly permeable) when formulated in immediate-release dosage forms. Another aspect to be considered is that the dissolution test should be run in a feasible amount of time. Based on the results obtained with 0.1 N HCl, it looks like it will take some time to release 70–80% of the label claim. In this situation, other parameters such as medium volume and agitation speed could be modified to obtain a more appropriate dissolution profile. The results obtained with pH 4.6 acetate buffer look promising, but it is necessary to verify which medium, hydrochloric acid or acetate buffer, is more discriminative for the critical parameters of this formulation and manufacturing process.