Q represents the targeted amount of active substance, expressed as a percentage of the label claim, which should be dissolved within a certain time. The ‘Q value’ should be seen as a “reference value” to which the dissolution results are compared. Such a comparison applies both to conventional-release dosage forms and the buffer stage of the dissolution test of gastro-resistant dosage forms.
For more information on dissolution testing, refer to general chapter 5.17.1. Recommendations on dissolution testing.