Acetazolamide is used in gout due to what effect on urine?

• A. It acidifies urine, promoting the elimination of uric acid
• B. It has no effect on urine pH
• C. It decreases uric acid excretion
• D. It alkalinizes urine, promoting uric acid excretion

Answer: (D)

The key idea is that urine pH affects how soluble uric acid is. Acetazolamide blocks carbonic anhydrase in the proximal tubule, causing bicarbonate to spill into the urine. This bicarbonate loss makes the urine more alkaline. Uric acid is more soluble in alkaline urine, so this alkaline urine environment increases the solubility of uric acid and promotes its excretion, helping to reduce uric acid buildup. If urine were acidified, uric acid would be less soluble and could crystallize or be excreted less efficiently. So, the reason this drug helps in gout is its ability to alkalinize urine, thereby promoting uric acid excretion.