ATT causing orange coloured urine is:
**Core Concept**
The question is testing the knowledge of a specific side effect of a commonly used medication, ATT (Anti-Tuberculosis Therapy), specifically the color change in urine due to a particular drug.
**Why the Correct Answer is Right**
The correct answer is related to the mechanism of action of one of the ATT drugs, Rifampicin. Rifampicin is a potent inducer of the hepatic enzyme UDP-glucuronyltransferase, which is responsible for the glucuronidation of bilirubin. However, Rifampicin also inhibits the enzyme UGT1A1, which is involved in the glucuronidation of bilirubin, leading to an increase in unconjugated bilirubin. As a result, Rifampicin causes a rise in the levels of unconjugated bilirubin, which is then excreted in the urine, giving it a characteristic orange or reddish color. This is due to the oxidation of bilirubin to biliverdin, which is responsible for the orange color.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as it does not explain the mechanism of action of Rifampicin and its effect on bilirubin levels.
* **Option B:** This option is incorrect as it is a different ATT drug, Isoniazid, which has a different side effect profile and does not cause orange-colored urine.
* **Option C:** This option is incorrect as it does not explain the mechanism of action of Rifampicin and its effect on bilirubin levels.
* **Option D:** This option is incorrect as it is a different ATT drug, Pyrazinamide, which also has a different side effect profile and does not cause orange-colored urine.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that Rifampicin can cause a harmless but noticeable change in urine color, which can be a diagnostic clue in cases where a patient is suspected to be taking ATT medications.
**Correct Answer:** C. Rifampicin