Which of the following antitubercular drug is preferred in severe liver disease?
**Core Concept**
The management of tuberculosis (TB) in patients with severe liver disease requires careful consideration of antitubercular drugs with minimal hepatotoxicity. The liver plays a crucial role in the metabolism and elimination of many drugs, and in severe liver disease, the clearance of these drugs may be impaired, leading to increased levels and toxicity.
**Why the Correct Answer is Right**
Ethambutol is the preferred antitubercular drug in severe liver disease because it has minimal hepatotoxicity compared to other first-line antitubercular drugs such as isoniazid, rifampicin, and pyrazinamide. Ethambutol is primarily excreted unchanged in the urine and does not undergo significant hepatic metabolism, making it a safer option in patients with severe liver disease.
**Why Each Wrong Option is Incorrect**
* **Option A:** Isoniazid is a first-line antitubercular drug, but it is known to cause hepatotoxicity, particularly when used in combination with rifampicin and pyrazinamide. Its use in severe liver disease would be contraindicated.
* **Option B:** Rifampicin is also a first-line antitubercular drug, but it is known to cause hepatotoxicity and is a potent inducer of cytochrome P450 enzymes, which can increase the metabolism of other drugs and potentially worsen liver function.
* **Option D:** Pyrazinamide is a first-line antitubercular drug, but it is known to cause hepatotoxicity and is often associated with liver enzyme elevations.
**Clinical Pearl / High-Yield Fact**
In patients with severe liver disease, the use of antitubercular drugs with minimal hepatotoxicity, such as ethambutol, is crucial to prevent further liver injury. The liver function tests should be closely monitored in these patients, and the use of other antitubercular drugs should be avoided if possible.
**Correct Answer:** C. Ethambutol