Antipruritic therapy with the oral opioid receptor antagonist naltrexone. Open, non-placebo controlled administration in 133 patients

Background and Objectives.The perception of pruritus is modified by endogenous and exogenous opioids via central opiate receptors and can be suppressed with opioid receptor antagonists. The aim of this investigation was to describe the efficacy and safety of naltrexone, an orally active opiate antagonist, in the treatment of severe, otherwise intractable pruritus of varying origins. Patients. A total of 133 patients with pruritus caused by inflammatory skin diseases (asteatotic dermatitis, atopic dermatitis, prurigo, and psoriasis vulgaris), liver- and renal diseases, cutaneous lymphoma, as well as with pruritus of unknown origin were treated with naltrexone (Nemexin™) 50 to 150 mg daily. Results. A therapeutic response was achieved in 86 of the 133 (64.6%) patients. Naltrexone was most effective in prurigo nodularis, cutaneous lymphoma and pruritus of unknown origin. Tachyphylaxis occurred in 13% of the patients, but appeared late, and could be counterbalanced by raising the dosage. Adverse drug effects were restricted to the first two weeks of treatment and included mainly neurological (dizziness, headache, fatigue) and gastrointestinal (nausea, vomiting, diarrhea) symptoms. Conclusions. The oral opiate antagonists may well be an effective, well-tolerated therapy for intractable pruritus in many diseases.