Topical PTH (1–34) is a novel, safe and effective treatment for psoriasis: a randomized self-controlled trial and an open trial
Background There continues to be a need to develop new pharmacological approaches for treating the common skin disease psoriasis. Human skin produces parathyroid hormone related peptide. This peptide is a potent inhibitor of epidermal cell growth.
Objectives A programme was initiated to determine whether an agonist of this peptide's receptor, PTH (1–34), could be developed as a drug to treat psoriasis.
Methods PTH (1–34) was formulated in Novasome A® cream. Fifteen adult patients with chronic plaque psoriasis who had failed to respond to at least one standard treatment were enrolled in a randomized double-blinded placebo self-controlled trial. The patients topically applied to a 25-cm2 psoriatic lesion 0·1 g of either Novasome A® cream or Novasome A® cream that contained 20 μg of PTH (1–34) twice a day for 2 months. At the end of the double-blind study, patients were enrolled in an open large area study. Ten patients applied PTH (1–34) (50 μg per 0·1 g) once daily to their psoriatic lesions. The patients were evaluated for their global improvement and calcium metabolism.
Results Novasome A® cream enhanced the percutaneous absorption of PTH (1–34) in human skin in comparison with formulations in propylene glycol or normal saline. Psoriatic lesions treated with PTH (1–34) showed marked improvement in scaling, erythema and induration. There was a 67·3% improvement in the global severity score for the lesion treated with PTH (1–34) compared with the placebo-treated lesion, which only showed a 17·8% improvement. Ten patients topically applied PTH (1–34) on all of their lesions in a stepwise manner. A Psoriasis Area and Severity Index score analysis of all the patients revealed improvement of 42·6% (P < 0·02). None of the patients experienced hypercalcaemia or hypercalciuria or developed any side-effect to the medication.
Conclusions Patients who were resistant to at least one standard therapy for psoriasis had a remarkable improvement in their psoriasis when they applied PTH (1–34) to their lesion(s). No untoward toxicity was observed in any of the subjects. This pilot study suggests that topical PTH (1–34) is a safe and effective novel therapy for psoriasis.