IV Acetaminophen

• •Acute mild-to-moderate pain
• •Multimodal analgesia (opioid-sparing component)
• •Antipyretic when NPO or unable to tolerate PO

Onset 5-10 min IV; peak 30 min; duration 4-6 hr; hepatic metabolism (glucuronidation + sulfation; minor CYP2E1 → toxic metabolite NAPQI cleared by glutathione).

• !Hepatotoxicity at supratherapeutic dose (>4 g/day adult; cumulative)
• !Hypotension (rare — typically with rapid infusion)
• !Hypersensitivity (rare; SJS/TEN very rare)

• ×Severe hepatic impairment (Child-Pugh C)
• ×Active alcohol abuse (depleted glutathione)
• ×Hypersensitivity to acetaminophen

N-acetylcysteine for hepatotoxicity (replenishes glutathione; most effective <8h post-ingestion but worthwhile up to 24h+).

• ★PERFECT MULTIMODAL ANCHOR: no bleeding, no renal effect, no platelet effect, no respiratory depression. Opioid-sparing 25-30% in most surgeries.
• ★DOSE STACKING: 4g/day total includes ALL routes (IV + PO + suppository). Combined OTC products (Vicodin, Percocet, Norco) often have 325 mg per pill — review meds list.
• ★HEPATIC DISEASE: Child-Pugh A/B → 2 g/day max; C → avoid. Chronic alcoholics: max 2 g/day.
• ★DON'T USE PROPHYLACTICALLY for hours — peak effect is 30 min after dose; given on schedule q6h around-the-clock for first 24-48 hr post-op.
• ★PRICE: IV form is ~50× more expensive than PO. Convert to oral as soon as patient tolerates.

• 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.

• Ketorolac

  Inhibits cyclooxygenase → ↓ prostaglandin synthesis → anti-inflammatory + analgesic + antipyretic.

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