Which of the following drug used in gout act by conveing uric acid into allantoin ?
**Core Concept**
The question is testing the student's knowledge of uric acid metabolism and the pharmacological treatment of gout. Specifically, it is asking about drugs that convert uric acid into allantoin, which is a soluble compound that can be easily excreted in the urine.
**Why the Correct Answer is Right**
The correct answer is **Febuxostat**. Febuxostat is a xanthine oxidase inhibitor that works by blocking the enzyme xanthine oxidase, which is responsible for converting hypoxanthine to xanthine and xanthine to uric acid. By inhibiting this enzyme, Febuxostat reduces the production of uric acid. Additionally, it also has a mild uric acid oxidase activity which converts uric acid into allantoin, making it more soluble and easier to excrete in the urine.
**Why Each Wrong Option is Incorrect**
* **Option A:** Allopurinol is a xanthine oxidase inhibitor, but it does not convert uric acid into allantoin. Instead, it reduces uric acid production by blocking the enzyme.
* **Option B:** Probenecid works by increasing the excretion of uric acid in the urine, but it does not convert uric acid into allantoin.
* **Option D:** Colchicine is a medication used to treat gout attacks, but it does not have any effect on uric acid metabolism.
**Clinical Pearl / High-Yield Fact**
Febuxostat is a useful alternative to allopurinol for patients who cannot tolerate allopurinol due to side effects such as skin rash or liver enzyme elevations.
**Correct Answer:** C. Febuxostat.