Efficacy and safety of naltrexone, an oral opiate receptor antagonist, in the treatment of pruritus in internal and dermatological diseases

Background: The perception of pruritus is modified by endogenous opiates vi a central opiate receptors in a histamine-independent manner. Objective: The aim of this pilot study was to evaluate the efficacy and saf ety of naltrexone, an orally active opiate antagonist, in the treatment of severe, otherwise intractable pruritus of different origin in an open-label clinical trial. Methods: A total of 50 patients with pruritus caused by internal diseases, hydroxyethyl starch, contact with water, cutaneous lymphoma, atopic dermati tis, xerosis cutis, macular amyloidosis, psoriasis, and other skin disorder s as well as with pruritus of unknown origin were randomly selected to rece ive naltrexone 50 mg daily The pruritus intensity was rated by the patients before and during therapy in a visual analogue scale. Results: A significant therapeutic response nas achieved in 35 of the 50 pa tients within 1 week (confidence limits of 0.55 and 0.82 at a confidence le vel of 0.95). Naltrexone uas of high antipruritic effect in 3 of 17 cases o f prurigo nodularis and contributed to healing of the skin lesions. Tachyph ylaxis plas infrequent (6/50), occurred late, and could be counterbalanced by raising the dosage in 2 patients. Adverse drug effects were restricted t o the first 2 weeks of treatment and included nausea (11/50), fatigue (3/50 ), dizziness, heartburn, and diarrhea (1/50 each). Conclusion: The study suggests that oral opiate antagonists might be a well -tolerated and effective therapy for pruritic symptoms in many diseases.