A 55-year-old man with acute primary angle closure is given oral acetazolamide 500 mg along with topical agents. Two hours later he reports tingling around the mouth and fingers and general malaise. The biochemical abnormality responsible is:
- A Hyperchloremic metabolic alkalosis
- B Metabolic acidosis with hypokalemia ✓
- C Respiratory acidosis with hyperkalemia
- D Lactic acidosis with normal electrolytes
Correct answer: B. Metabolic acidosis with hypokalemia
Explanation
Acetazolamide inhibits carbonic anhydrase in the proximal renal tubule, causing bicarbonate diuresis with sodium and potassium loss, producing a hyperchloremic metabolic acidosis and hypokalemia. The same enzyme inhibition in the ciliary processes lowers aqueous secretion. Paresthesias are the classic dose-related symptom. Respiratory acidosis is impossible with this drug, and lactic acidosis is associated with metformin, not acetazolamide.
Reference: Katzung, Basic and Clinical Pharmacology, 16th ed.
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