Which topical antimicrobial used in burns is associated with metabolic acidosis as a potential adverse effect?

• A. Silver sulfadiazine.
• B. Mafenide acetate.
• C. Povidone-iodine.
• D. Neomycin.

Answer: (B)

Topical antimicrobials used on burn wounds can be absorbed into the circulation, and one agent in particular has a well-known metabolic complication. Mafenide acetate can penetrate burned tissue and, when absorbed systemically, acts similarly to carbonic anhydrase inhibitors in the kidney. This inhibits tubular bicarbonate reabsorption, leading to loss of bicarbonate and a non‑anion gap metabolic acidosis. In patients with large burn areas, this acidosis can be clinically meaningful, so acid-base status should be monitored and the drug reconsidered if acidosis develops.

Other topical agents used in burns have different adverse effect profiles and are not typically associated with metabolic acidosis. For example, silver sulfadiazine can cause neutropenia and hypersensitivity reactions, povidone-iodine can affect thyroid function with significant uptake in some patients, and neomycin carries risks of nephrotoxicity and ototoxicity if absorbed.