Hydromorphone
Dilaudid
Semisynthetic μ-opioid agonist (hydrogenated ketone of morphine)
μ-opioid agonist ~5–7× more potent than morphine. No clinically significant active metabolites → safer than morphine in renal failure. Less histamine release.
Indications
- •Postop analgesia
- •PCA
- •Chronic/cancer pain
- •Neuraxial analgesia
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| IV bolus | 0.2–1 mg (0.01–0.02 mg/kg) q2–3h | 0.01–0.02 mg/kg IV |
| PCA | 0.1–0.3 mg q6–10 min | — |
| Epidural | 0.5–1 mg | — |
Pharmacokinetics
Onset ~5 min IV, peak 10–20 min, duration 3–4 h. Hepatic glucuronidation.
Hemodynamic effects
Minimal; less histamine release than morphine.
Respiratory effects
Dose-dependent respiratory depression.
Side effects
- !Respiratory depression
- !N/V
- !Pruritus (less than morphine)
- !Sedation, constipation
Contraindications
- ×MAOI within 14 days (relative)
Reversal / antidote
Naloxone
Clinical pearls
- ★Preferred over morphine in renal failure (no active renally-cleared metabolite).
- ★~1.5 mg IV ≈ 10 mg IV morphine — the 5–7:1 potency ratio makes dosing errors a known 'never event'; double-check.
- ★Cleaner side-effect profile than morphine (less histamine, less pruritus).
Other drugs in Narcotics & Analgesics
- Fentanyl
μ-opioid receptor agonist. ~100× potency of morphine.
- Remifentanil
μ-opioid agonist. Ester linkage hydrolyzed by nonspecific tissue + plasma esterases — no organ-dependent clearance.
- Morphine
μ-opioid receptor agonist. Active metabolite morphine-6-glucuronide (M6G) is analgesic and renally cleared — accumulates in renal failure → prolonged sedation/respiratory depression. Causes histamine release.
- Sufentanil
Most potent opioid in common clinical use — ~1000× morphine, ~10× fentanyl. High lipid solubility.
- Alfentanil
μ-opioid agonist ~1/5–1/10 the potency of fentanyl but FASTEST onset of the family — low pKa means a high non-ionized fraction at physiologic pH.
- Meperidine
μ-opioid agonist ~1/10 morphine, plus κ-agonism (anti-shivering). Active metabolite normeperidine is renally cleared, proconvulsant, and neurotoxic.
- Methadone
μ-opioid agonist with NMDA-receptor antagonism (blunts tolerance + opioid-induced hyperalgesia) and monoamine reuptake inhibition. Very long, variable half-life.
Suggested reading
- •Stoelting & Hines, Pharmacology & Physiology in Anesthetic Practice, 6e
- •Miller's Anesthesia, 9e
- •FDA package insert
