Risperidone microspheres release gradually and produce therapeutic levels in how many weeks?

• A. 2-3 weeks
• B. 3-4 weeks
• C. 5-6 weeks
• D. 1-2 weeks

Answer: (B)

Risperidone microspheres are a long-acting injectable formulation that releases the drug slowly over time. The polymer matrix gradually degrades, delivering risperidone in a steady, extended manner, so plasma concentrations rise gradually rather than immediately. Because of this slow release, therapeutic levels are typically reached only after about three to four weeks. That’s why this option is the best fit. A much shorter timeframe, like one to two weeks, would not align with the sustained-release design, and waiting five to six weeks would imply an even longer delay than usual for achieving therapeutic levels. In practice, this gradual onset explains why clinicians plan for the gradual buildup and may provide bridging coverage when starting therapy.