A patient receives dexamethasone for PONV prophylaxis. The optimal timing for its administration to achieve maximum antiemetic efficacy is:

• A 1 hour before induction
• B After nausea develops in the PACU
• C At the end of surgery
• D At induction of anaesthesia ✓

Explanation

Dexamethasone is most effective for PONV prophylaxis when given at induction of anaesthesia rather than at the end of surgery. This ensures adequate tissue levels during the emetogenic stimulus. Its action involves central prostaglandin inhibition and anti-inflammatory effects, which take time to develop. Administering it in the PACU after symptoms appear is treatment, not prophylaxis.

Reference: Miller's Anesthesia, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.