Which drug class is associated with metallic taste, tingling in extremities, metabolic acidosis, and myopic shifts?

• A. Topical carbonic anhydrase inhibitors
• B. Prostaglandin analogs
• C. Beta blockers
• D. Oral carbonic anhydrase inhibitors

Answer: (D)

This set of symptoms points to the systemic effects of oral carbonic anhydrase inhibitors. When taken systemically, these drugs block carbonic anhydrase in the kidney, causing bicarbonate loss and a non‑anion gap metabolic acidosis. That bicarbonate loss can produce a metallic taste and tingling in the extremities (paresthesias) as the body responds to the acid–base disturbance. In the eye, lower bicarbonate levels in the aqueous humor and changes in ciliary body dynamics can lead to a forward shift of the lens-iris diaphragm, causing a transient myopic shift. Topical carbonic anhydrase inhibitors can cause taste disturbance but rarely produce the full metabolic acidosis and paresthesias seen with the oral form, and the other drug classes listed have different adverse effect profiles.