The perception of pruritus is modified by endogenous opiates via central opiate receptors in a histamine-independent manner.

The aim of this pilot study was to evaluate the efficacy and safety of naltrexone, an orally active opiate antagonist, in the treatment of severe, otherwise intractable pruritus of different origin in an openlabel clinical trial.

A total of 50 patients with pruritus caused by internal diseases, hydroxyethyl starch, contact with water, cutaneous lymphoma, atopic dermatitis, xerosis cutis, macular amyloidosis, psoriasis, and other skin disorders as well as with pruritus of unknown origin were randomly selected to receive naltrexone 50 mg daily. The pruritus intensity was rated by the patients before and during therapy in a visual analogue scale.

A significant therapeutic response was achieved in 35 of the 50 patients within 1 week (confidence limits of 0.55 and 0.82 at a confidence level of 0.95). Naltrexone was of high antipruritic effect in 9 of 17 cases of prurigo nodularis and contributed to healing of the skin lesions. Tachyphylaxis was infrequent (6/50), occurred late, and could be counterbalanced by raising the dosage in 2 patients. Adverse drug effects were restricted to the first 2 weeks of treatment and included nausea (11/50), fatigue (3/50), dizziness, heartburn, and diarrhea (1/50 each).

The study suggests that oral opiate antagonists might be a well-tolerated and effective therapy for pruritic symptoms in many diseases.