Which condition is a contraindication for oral CAIs?

• A. Asthma
• B. Renal failure
• C. Hyperlipidemia
• D. Migraine

Answer: (B)

Oral carbonic anhydrase inhibitors lower intraocular pressure by reducing aqueous humor production, achieved by blocking carbonic anhydrase in the eye and kidney. The kidney-facing effect is bicarbonate loss and a tendency toward metabolic acidosis. In renal failure, the kidneys can’t properly handle this bicarbonate loss or maintain acid-base balance, so the drug can accumulate and worsen acidosis and electrolyte disturbances. That makes renal failure a contraindication for systemic CAIs. The other conditions listed don’t inherently prevent their use; they don’t involve the critical need to preserve renal acid-base balance in the context of this medication.