Pharmacology · patient case question
Which adverse effect can an ester local anaesthetic cause?
Patient case: Trauma, pigmented lesions, anaesthetics and confidentiality
Scenario: Four items.
Show answer and explanation
Correct answer: D. Methaemoglobinaemia
- A. Local anaesthetics are not characteristically nephrotoxic.
- B. Ototoxicity belongs to the aminoglycosides and to high-dose loop diuretics.
- C. Malignant hyperthermia is triggered by volatile anaesthetics and succinylcholine, not by local anaesthetics.
- D. Correct. Benzocaine, an ester, is the agent most associated with methaemoglobinaemia — the patient becomes cyanotic and the oxygen saturation fails to improve with oxygen. Methylene blue is the antidote.
Note: Prilocaine, an amide, causes methaemoglobinaemia by a different route — its metabolite o-toluidine. Esters are also the group associated with allergy, because of the PABA metabolite.