The current most important topical treatments for psoriasis are vitamin D3 analogues and/or corticosteroids. The possibility of another effective treatment for psoriasis could be based on the immunosuppressive efficacy of selective blockers of a lymphocyte potassium channel.

The aim of the clinical trial is to evaluate the safety, tolerability and anti-psoriatic efficacy of topical SPS4251 formulations in comparison to placebo and to a marketed topical Vitamin-D analogue ointment in a psoriasis plaque test.

Inclusion Criteria:

• men aged 18 years or older
• subjects with mild to moderate psoriasis vulgaris in a chronic stable phase
• subject with up to three stable plaques with an area sufficient for five treatment fields
• Plaques to be treated should have a comparable thickness of the Echo Lucent Band of at least 200 µm

Exclusion Criteria:

• Subjects with guttate psoriasis, punctate psoriasis, erythrodermic psoriasis, psoriatic arthropathy and pustular psoriasis
• Local treatment with antipsoriatics in the 4 weeks preceding and/or during the trial, and any topical antipsoriatic treatment on the plaques to be treated in this trial in the 8 weeks before first treatment and/or during the trial
• Systemic treatment with antipsoriatics e.g. corticosteroids, cytostatics, retinoids in the three months before first treatment and during the trial;
• Treatment with systemic medications or medications acting locally which might have countered or influenced the trial aim
• Contraindications according to summary of product characteristics of Daivonex® Ointment;
• UV-therapy within four weeks before first treatment and during the trial
• Symptoms of a clinically significant illness that may influence the outcome of the trial in the four weeks before baseline visit and during the trial
• Any history of cardiovascular disease
• Any evidence of ECG abnormality on screening ECG
• Close affiliation with the Investigator (e.g. a close relative) or persons working at bioskin GmbH or subject is an employee of the Sponsor;
• Subject is institutionalized because of legal or regulatory order.