摘要
We report the first case of a life-threatening immediate-type hypersensitivity caused by Dynexan., a local anaesthetic gel. After mucosal application by his dentist, a 63-year-old man rapidly developed urticaria, dyspnea and, at last, he collapsed and remained unconscious for 2 hr despite emergency care. While the standard prick tests were negative to all local anaesthetics tested including lidocaine, a 1-fold positive reaction was detected to Meyprogat 60., an ingredient of Dynexan.. As the gelling agent Meyprogat 60. represents a derivative of guar (synonymous guar gum, guaran, E-412), we subsequently tested different guar products derived from Cyamopsis tetragonolobabeansand,ascontrol,thecloselyrelatedlocustbeangum E-410. In the prick-to-prick tests, the guar-derived food additive Provigel. NAG 905 provoked a 1-fold positive reaction. Native guar beans pounded and resuspended in water showed a 2-fold positive reaction, whereas no reaction was found to derivatives of locust bean gum. Specific immunoglobulin E were negative in all cases. Despite the common use of guar as versatile food additive or gelling agent, this is the first case of a severe immediate-type hypersensitivity after mucosal contact.
We report the first case of a life-threatening immediate-type hypersensitivity caused by Dynexan., a local anaesthetic gel. After mucosal application by his dentist, a 63-year-old man rapidly developed urticaria, dyspnea and, at last, he collapsed and remained unconscious for 2 hr despite emergency care. While the standard prick tests were negative to all local anaesthetics tested including lidocaine, a 1-fold positive reaction was detected to Meyprogat 60., an ingredient of Dynexan.. As the gelling agent Meyprogat 60. represents a derivative of guar (synonymous guar gum, guaran, E-412), we subsequently tested different guar products derived from Cyamopsis tetragonolobabeansand,ascontrol,thecloselyrelatedlocustbeangum E-410. In the prick-to-prick tests, the guar-derived food additive Provigel. NAG 905 provoked a 1-fold positive reaction. Native guar beans pounded and resuspended in water showed a 2-fold positive reaction, whereas no reaction was found to derivatives of locust bean gum. Specific immunoglobulin E were negative in all cases. Despite the common use of guar as versatile food additive or gelling agent, this is the first case of a severe immediate-type hypersensitivity after mucosal contact.
