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Contrast-Induced Nephropathy Prevention Pregnancy: Generally considered safe — used for paracetamol overdose in pregnancy; risk/benefit for CIN prevention low risk

N-Acetylcysteine (Contrast Nephropathy)

Brand names: Parvolex (IV), effervescent tablets (oral)

Adult dose

Dose: 600 mg twice daily orally on the day before and day of contrast administration (total 4 doses). IV: 150 mg/kg in 500 mL NS over 30 min pre-contrast, then 50 mg/kg in 500 mL NS over 4 hours.
Route: Oral or IV
Frequency: BD oral (day before + day of); IV as single pre-procedure course
Max: 600 mg BD oral; IV doses per protocol
Antioxidant — proposed mechanism is free radical scavenging to protect tubular cells from contrast-induced oxidative stress. High volume IV saline hydration remains the primary prophylaxis. Evidence for NAC in CIN is controversial — PRESERVE trial was negative.

Paediatric dose

Route: Oral or IV
Frequency: Per protocol
Max: Per protocol
Seek specialist opinion for paediatric contrast nephropathy protocols

Dose adjustments

Renal

No adjustment needed — used specifically in pre-existing renal impairment as the target population

Hepatic

No dose adjustment required

Clinical pearls

  • PRESERVE trial (Weisbord et al. NEJM 2018): largest RCT of CIN prevention — IV NAC vs IV sodium bicarbonate vs isotonic saline; 2x2 factorial design (5,177 patients). Neither NAC nor bicarbonate reduced AKI or dialysis requirement vs isotonic saline alone. Definitively negative for NAC benefit in high-risk patients.
  • Despite PRESERVE, NAC is still widely used empirically because it is cheap, safe, and there is biological plausibility. NICE and many centres do not mandate its use but also do not prohibit it.
  • IV normal saline (0.9% NaCl) remains the only proven intervention for CIN prevention: 1 mL/kg/hour for 6-12 hours before and 6-12 hours after contrast. This should NEVER be omitted in favour of or alongside NAC.
  • CIN risk factors: eGFR <60, diabetes, heart failure, dehydration, nephrotoxic drugs (NSAIDs, aminoglycosides), contrast volume >100 mL, high-osmolar contrast. Use iso-osmolar contrast (iodixanol) in high-risk patients.
  • NAC also has a well-established role in paracetamol overdose (via N-acetylcysteine IV) and as nebulised mucolytic — do not confuse these different pharmacological uses.

Contraindications

  • Hypersensitivity to acetylcysteine

Side effects

  • Oral: nausea, vomiting, rash (generally mild)
  • IV: anaphylactoid reactions (histamine release — more common at higher doses/rapid infusion; pre-medicate in high-risk)

Interactions

  • Activated charcoal — reduces oral absorption; do not co-administer
  • Nitroglycerin — hypotension when combined IV

Monitoring

  • Creatinine/eGFR at 48-72 hours post-contrast
  • Urinary output during and after contrast procedure
  • Signs of anaphylactoid reaction (IV route)

Reference: BNFc; BNF 90; PRESERVE Trial (Weisbord et al. NEJM 2018); NICE CKD Guidelines; SPC Parvolex; RCR Guidance on Contrast Media. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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