Λεξικό .. Benzocaine

Benzocaine is a derivative of para-aminobenzoic acid (PABA) with local anesthetic properties. It is soluble in oil and may be incorporated in oily solutions, ointments and suppositories. For that reason is too slowly absorbed to be toxic. It can be applied directly to wounds and ulcerated surfaces, where it remains localized for long periods of time to produce sustained anesthetic action.

Benzocaine has been shown to be a potent sensitizer. In spite of that it is still widely used as a local surface anesthetic agent included in anti-pruritic preparations, burn and sunburn remedies, hemorrhoidal preparations, and agents used to treat poison-ivy rashes. Benzocaine can cross-react with other PABA esters, such as procaine (Novocaïne) and dubucaine (Nupercaine). Amide type local anesthetics (e.g. lidocaine) are rarely allergenic and do not cross-react with benzocaine. Benzocaine should be avoided because it can produce sensitization if applied to normal or relatively undamaged skin [1].

Severe methemoglobinemia resulting from the use of topical benzocaine has been reported in adults and  children as a rare complication[2]. Because of the potential for severe complications, methemoglobinemia should be corrected promptly in compromised patients and those with toxic benzocaine concentrations. The possibility of masking symptoms during general anesthesia carries special risk of use of this agent in the preanesthesia setting [3]..

1. Covino, B.G.: Clinical Pharmacology of Local Anaesthetic Agents. Br. J. anaesth. 1986:58(7):701-716.

2. Dahshan A, Donovan GK. Severe methemoglobinemia complicating topical benzocaine use during endoscopy in a toddler: a case report and review of the literature. Pediatrics. 2006 Apr;117(4):e806-9.

3.Rodriguez LF, Smolik LM, Zbehlik AJ. Benzocaine-induced methemoglobinemia: report of a severe reaction and review of the literature. Ann Pharmacother. 1994 May;28(5):643-9. Comment in: Ann Pharmacother. 2000 Sep;34(9):1077.