What enzyme does allopurinol inhibit?

Allopurinol primarily acts by inhibiting xanthine oxidase, an enzyme that plays a crucial role in the purine degradation pathway. The inhibition of xanthine oxidase leads to a decrease in the conversion of hypoxanthine and xanthine to uric acid. As a result, allopurinol effectively lowers serum uric acid levels, making it beneficial for the treatment of conditions associated with elevated uric acid, such as gout and certain types of kidney stones.

By inhibiting this specific enzyme, allopurinol reduces the production of uric acid, thereby preventing the formation of uric acid crystals and alleviating associated symptoms in patients with gout. This targeted mechanism of action is important in managing hyperuricemia and its complications.

Other enzymes mentioned in the options have distinct roles and are targeted by different classes of drugs. For example, 5α reductase is involved in steroid metabolism, and its inhibitors are used primarily for conditions like benign prostatic hyperplasia. COX-1 is associated with prostaglandin synthesis, and inhibitors are typically nonsteroidal anti-inflammatory drugs (NSAIDs). Lastly, carbonic anhydrase is involved in bicarbonate transport and is inhibited by certain diuret