The purpose of this trial is to compare the anti-psoriatic effect of eight different formulations of vitamin D analogues using a psoriasis plaque test design

Inclusion Criteria:

• Subjects having understood and signed an informed consent form.
• Either sex
• Age 18 years or above
• All skin types and any ethnic origin
• Subjects with a diagnosis of psoriasis vulgaris with lesions located on arms, legs or trunk.

Exclusion Criteria:

• Females who are pregnant, or who wish to become pregnant during the study, or who are breast feeding

• Systemic treatment with biological therapies (marketed or not marketed) with a possible effect on psoriasis vulgaris within 4 weeks (etanercept), 2 months (adalimumab, alefacept, infliximab), 4 months (ustekinumab) or 4 weeks/5 half-lives (which-ever is longer) for experimental biological products prior to randomisation

• Systemic treatments with all other therapies than biologicals, with a potential effect on psoriasis vulgaris (e.g., corticosteroids, vitamin D analogues, retinoids, immuno-suppressants) within the 4-week period prior to randomisation

• Subjects using one of the following topical drugs for the treatment of psoriasis within the 4 week period prior to randomisation and during the study:

  • Potent or very potent (WHO group III-IV) corticosteroids
  • PUVA or Grenz ray therapy

• Subjects using one of the following topical drugs for the treatment of psoriasis within two weeks prior to randomisation and during the study:

  • WHO group I-II corticosteroids (except if used for treatment of scalp psoriasis)
  • Topical retinoids
  • Vitamin D analogues
  • Topical immunomodulators (e.g. macrolides)
  • Anthracen derivatives
  • Tar
  • Salicylic acid
  • UVB therapy

• Subjects known to be non-responder to topical vitamin D analogues (e.g., known history of no improvement or worsening of psoriasis with e.g., calcipotriol, calcitriol or tacalcitol when used according to current SmPc)

• Subjects who have received treatment with any non-marketed drug substance (i.e., an agent which has not yet been made available for clinical use following registration) within the 4 week period prior to randomisation or longer, if the class of the substance requires a longer washout as defined above (e.g., biological treatments)

• Subjects with current participation in any other interventional clinical, based on interview of the subject

• Subjects with current diagnosis of guttate, erythrodermic, exfoliative or pustular psoriasis

• Subjects with known or suspected hypersensitivity to component(s) of the investigational products

• Subjects with known/suspected disorders of calcium metabolism associated with hypercalcaemia

• Subjects with known severe hepatic and/or severe renal insufficiency

• Subjects with any concomitant medical or dermatological disorder(s) which might preclude accurate evaluation of the psoriasis