Liquid phenytoin suspensions should be shaken prior to pouring.

• A. Should
• B. Should not
• C. May
• D. Not necessary

Answer: (A)

Uniform distribution of drug particles in a suspension is essential for accurate dosing. Liquid phenytoin is a suspension, not a true solution, so the solid particles settle to the bottom over time. If you don’t shake, the portion you pour may be richer or poorer in drug than intended, leading to inconsistent, potentially subtherapeutic or toxic doses. Shaking re-suspends the particles so the entire mixture has a uniform concentration, ensuring each dose contains the intended amount of phenytoin. Because phenytoin has a narrow therapeutic index, this consistent dosing is crucial.