Drug-Induced Liver Injury (DILI) - Management According to Sleisenger and Fordtran's Gastrointestinal and Liver Disease

1. Core Principle: Prevention Over Treatment

• Prevention and early detection
• Prompt withdrawal of the offending agent
• Safe use of OTC agents (acetaminophen, NSAIDs, complementary and alternative medicine [CAM] preparations)

2. Prevention Strategies

A. Idiosyncratic Hepatotoxins

• Avoid overuse - e.g., amoxicillin-clavulanic acid, flucloxacillin
• Avoid polypharmacy when possible
• Post-marketing surveillance and adverse effect reporting to monitoring agencies is mandatory

B. Dose-Dependent Hepatotoxins

• Adhere to dosage guidelines or monitor blood levels
• This approach has virtually abolished certain forms of DILI:
  • Tetracycline-induced fatty liver
  • Aspirin hepatitis
  • Methotrexate-induced hepatic fibrosis
• Specific contraindications:
  • Avoid valproic acid with other drugs in children < 3 years
  • Avoid methotrexate in excess alcohol consumers
  • Moderate acetaminophen doses are contraindicated in heavy drinkers and after prolonged fasting
  • Halothane should NOT be readministered within 28 days or in patients with suspected prior sensitivity to a haloalkane anesthetic

3. Early Detection

• Warn patients to report: unexplained nausea, malaise, right hypochondrial pain, lethargy, or fever - these may represent the prodrome of drug-induced hepatitis
• These symptoms are an indication for liver biochemical testing
• If liver tests suggest injury - stop the drug

Protocol Screening Recommendations:

• Routine (protocol) screening is NOT generally recommended, as:
  • Liver injury onset can be rapid, making monthly screening futile
  • Up to 7.5% of placebo-treated patients have persistently raised ALT
• Exceptions where protocol screening IS recommended:
  • Methotrexate (with biopsy/noninvasive fibrosis assessment)
  • Valproic acid, isoniazid, pyrazinamide, ketoconazole, dantrolene, thiazolidinediones, synthetic retinoids

Threshold for Stopping a Drug (using isoniazid as the model):

• Stop if serum ALT > 250 U/L or > 5x ULN
• Clearer indications to stop: elevated serum bilirubin, decreased albumin, prolonged prothrombin time, or any pertinent symptoms
• Note: Rise in serum GGTP or minor elevation of alkaline phosphatase usually indicates hepatic adaptation, not injury

4. General Management of Established DILI

"Failure to discontinue the offending drug is the single most important factor leading to poor outcomes, such as ALF and chronic liver disease."

• Aspiration of stomach contents (metals, acetaminophen)
• Methods to remove absorbed toxins: charcoal hemoperfusion, hemodialysis (limited efficacy)

• NAC (N-acetylcysteine): Can be used in acute liver failure (ALF) from DILI (not just acetaminophen)
• UDCA (ursodeoxycholic acid): May help in managing drug-induced cholestasis
• Glucocorticoids: Generally ineffective in drug-induced liver disease
  • Reserved for atypical/refractory cases - occasional effectiveness reported with etretinate, allopurinol, diclofenac, or ketoconazole
  • Should be reserved especially for cases associated with vasculitis
• Early referral for liver transplantation in ALF

5. Specific Management - Acetaminophen (Paracetamol) Hepatotoxicity

Initial Steps:

Risk Assessment:

• Measure serum acetaminophen levels (wait until >4 hours post-ingestion for reliable interpretation)
• Use the Rumack-Matthew nomogram (blood level vs. time after ingestion) to estimate hepatotoxicity risk
• Indications for antidote therapy:
  • Reliable history of major poisoning (>10 g)
  • Blood levels in moderate- or high-risk bands on nomogram

Antidote - N-Acetylcysteine (NAC):

• IV route: higher rate of hypersensitivity reactions (rash, angioedema, shock) - must be administered under close supervision
• In NAC-sensitized patients: methionine is an alternative (not commercially available; causes vomiting)
• Timing is critical: outcomes worsen with presentation > 16 hours after ingestion

Prognosis / LT Criteria:

• Assess candidacy for LT in established severe hepatic injury
• King's College Criteria are used (pH < 7.30 regardless of grade of encephalopathy; or PT > 100s + creatinine > 300 µmol/L + grade III-IV encephalopathy)

6. Valproic Acid - Specific Management

• Treatment is supportive
• IV L-carnitine supplementation can reduce hyperammonemia and improve survival in severe cases (small nonrandomized studies)
  • Also useful for hyperammonemic encephalopathy without overt liver disease (psychiatric patients)
• LT has been performed but poor outcomes reported in children; may be good in selected adults
• Prevention: Avoid in children < 3 years with polypharmacy; screen high-risk groups for POLG mutations

Summary Table