Anti TB drug not toxic to liver is-
**Core Concept**
Anti-tubercular therapy involves the use of multiple drugs to combat Mycobacterium tuberculosis infection, with varying degrees of hepatotoxicity. The liver is a common organ affected by these drugs, leading to the need for careful monitoring and selection of medications with minimal risk of liver damage.
**Why the Correct Answer is Right**
The correct answer, Ethambutol, is not significantly hepatotoxic compared to other anti-tubercular drugs. Ethambutol is primarily metabolized by the kidneys and does not undergo significant hepatic metabolism, making it a safer choice for patients with liver dysfunction. Its mechanism of action involves inhibiting the synthesis of the mycobacterial cell wall, which is crucial for bacterial survival.
**Why Each Wrong Option is Incorrect**
**Option A:** Isoniazid is a well-known hepatotoxin, causing liver damage in a significant proportion of patients, particularly those with pre-existing liver disease. It is metabolized by the liver and can lead to severe hepatotoxicity, making it a less desirable choice for patients with liver issues.
**Option B:** Rifampicin is another hepatotoxic anti-tubercular drug, causing liver damage through the induction of cytochrome P450 enzymes, which can lead to increased oxidative stress and liver injury.
**Option C:** Pyrazinamide is also hepatotoxic, with a risk of liver damage that is higher than Ethambutol. It is metabolized by the liver and can cause severe hepatotoxicity, particularly when used in combination with other hepatotoxic drugs.
**Option D:** Streptomycin is an aminoglycoside antibiotic used in the treatment of tuberculosis. While it is not hepatotoxic, it is not the correct answer as the question specifically asks for an anti-tubercular drug not toxic to the liver.
**Clinical Pearl / High-Yield Fact**
When initiating anti-tubercular therapy, it is essential to monitor liver function tests regularly, particularly in patients with pre-existing liver disease or those taking other hepatotoxic medications.
**Correct Answer:** C. Pyrazinamide is also hepatotoxic, with a risk of liver damage that is higher than Ethambutol.