Which instrument can determine the amount of dissolved drug?

Which instrument can determine the amount of dissolved drug?

• A. Analytical balance
• B. Dissolution tester
• C. Brookfield viscometer
• D. Dioctyl phthalate spray

Answer: (B)

Determining how much drug has dissolved requires a device that directly monitors the release of drug from a dosage form into a liquid medium over time. A dissolution tester is designed for this purpose: it places the dosage form in a controlled dissolution medium, maintains the specified temperature and agitation, and at set intervals withdraws samples. The drug content in those samples is then quantified, giving the amount dissolved at each time point. This directly measures dissolved drug rather than solid mass, viscosity, or unrelated properties. An analytical balance weighs solids, a Brookfield viscometer measures how thick the liquid is, and a dioctyl phthalate spray isn’t an instrument for measuring dissolution. Hence, the dissolution tester is the appropriate instrument to determine the amount dissolved.