Severe Adverse Reactions to Dental Local Anaesthetics

Abstract

In the article by Sambrook et al.,1 articaine is wrongly blamed to be a risk factor for methaemoglobinaemia in humans. In the article by Wilburn-Goo and Lloyd,2 cited as reference 18 by Sambrook et al., articaine is not even mentioned at all. Higher doses of articaine than commonly administered in dental practice did not increase methaemoglobin in humans undergoing liposuction.3, 4 Besides, prilocaine which is without any doubt the local anaesthetic with the highest potency to induce methaemoglobinaemia, the second amide local anaesthetic mentioned by Wilburn-Goo and Lloyd2 is lidocaine. This is in line with conclusions from an extensive review of local anaesthetics that metabolize to 2,6-xylidine (bupivacaine, etidocaine, lidocaine, mepivacaine and ropivacaine) or o-toluidine (prilocaine).5 These two metabolites of amide local anaesthetics have a carcinogenic potential. Whereas 2,6-xylidine is classified by the International Agency for Research on Cancer as possibly carcinogenic (group 2B), o-toluidine is classified as carcinogenic to humans (group 1).6 Recently, oral administration of prilocaine has been shown to result in high adduct levels of o-toluidine, a direct proof of its metabolic activation to a carcinogen.7 This should be another reason to avoid therapeutic use of prilocaine when ever possible.