## Remifentanil: Ultra-Short Acting Opioid **Key Point:** Remifentanil is a synthetic opioid with an onset time of 1 minute and duration of action of only 3–5 minutes due to rapid ester hydrolysis by non-specific plasma and tissue esterases. **High-Yield:** Remifentanil is the opioid of choice for: - Rapid sequence intubation (RSI) - Short procedures requiring rapid recovery - Situations where quick offset is critical - Patients requiring rapid emergence from anesthesia ## Comparison of Common Opioids | Opioid | Onset (min) | Duration (min) | Metabolism | Clinical Use | |--------|-------------|----------------|------------|---------------| | Remifentanil | 1 | 3–5 | Ester hydrolysis | RSI, short procedures | | Fentanyl | 3–5 | 30–60 | Hepatic | General anesthesia, analgesia | | Morphine | 5–10 | 180–240 | Hepatic glucuronidation | Postoperative pain, chronic pain | | Codeine | 30–60 | 240–360 | Hepatic (prodrug) | Mild-to-moderate pain, cough | **Clinical Pearl:** Remifentanil's rapid offset is due to ester linkage hydrolysis, making it independent of hepatic or renal function — ideal in critically ill patients. **Mnemonic:** **REMIFENTANIL = RAPID ESTER METABOLISM** — the ester bond is cleaved rapidly, allowing quick recovery even with prolonged infusions. [cite:Harrison 21e Ch 473] 
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