Naphazoline intoxication: course and therapy

Abstract

As potent alpha-adrenergic agonists imidazoline derivatives like naphazoline are frequently used drugs because of their vasoconstrictive and decongestant properties. Beside their well-known local side effects also rare systemic ones like hypertension, excitability and nausea are possible. In case of intoxication this can enhance to ischemia of vital organs, bradycardia with arrhythmia, respiratory depression, hypothermia, excitation or marked sedation. Two cases of intoxication after application of naphazoline for haemostasis under the operation, the postoperative course and therapy are reported. No specific antidote is available but a symptomatic drug therapy with intravenous administration of 5 mg phentolamine, an alpha-adrenoceptor antagonist acts against the vasoconstrictive side effects. Because of the serious side effects and the narrow therapeutic to toxic window of naphazoline a strict observance of guidelines and contradictions, such as maximum dose, is necessary.