Question

The anti-tubercular drug safe in liver disease is

• A. INH
• B. Rifampicin
• C. Ethambutol
• D. Pyrazinamide

Hint:

Think about which first-line ATT drug's toxicity is ocular rather than hepatic.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks which first-line anti-tubercular drug can be used without a major risk of causing further liver injury in a patient who already has liver disease.

Step 2: Key Concept or Approach:
Among the standard four-drug ATT regimen (Isoniazid, Rifampicin, Pyrazinamide, Ethambutol), three are recognised hepatotoxic agents, while Ethambutol has a different toxicity profile that spares the liver. Its main adverse effect is optic neuritis (red-green colour blindness, reduced visual acuity), not hepatitis, which is why it is preferred when hepatic function is already compromised.

Step 3: Working Through the Options:
Isoniazid causes dose-independent hepatocellular injury and is a well-known cause of drug-induced hepatitis, so it is unsafe. Rifampicin can cause cholestatic jaundice and adds to the hepatotoxic burden when combined with isoniazid. Pyrazinamide is the most hepatotoxic of the first-line drugs and is usually the first one withdrawn if liver enzymes rise sharply. Ethambutol, in contrast, is eliminated mainly by the kidney and does not carry a significant hepatotoxic risk, which is why it is retained even in patients with liver disease.

Step 4: Conclusion:
The anti-tubercular drug that is safe in liver disease is Ethambutol.