Cromoglicate in Psoriasis

Inclusion Criteria: * Signed informed consent has been obtained * Age 18 years or above * Either sex * Any race or ethnicity * Attending hospital outpatient clinic or the private practice of a dermatologist * Clinical diagnosis of stable plaque psoriasis of at least 6 months with a symmetric distribution * Two treatment areas with a symmetrical distribution each corresponding to 2-3% BSA (Body Surface Area) and each including at least one itchy psoriasis plaque * Itchy psoriasis on both intended treatment areas of at least 40mm on the Visual Analogue Scale (VAS) with a maximum difference of 10mm on the visual analogue scale between each of the two treatment areas * Disease severity graded mild, moderate or severe according to the Physician's global assessment (PGA) of disease severity on psoriasis plaques on each of the two treatment areas. The disease severity must be the same for both treatment areas Exclusion Criteria: * Systemic treatment with biological therapies, whether marketed or not, with a possible effect on psoriasis vulgaris within the following time periods prior to randomisation: * etanercept - within 4 weeks prior to randomisation * adalimumab, infliximab - within 8 weeks prior to randomisation * ustekinumab - within 16 weeks prior to randomisation * other products - 4 weeks/5 half-lives (whichever is longer) * Systemic treatment with all other therapies with a possible effect on psoriasis vulgaris (e.g., corticosteroids, retinoids, methotrexate, ciclosporin, fumaric acid derivatives, and other immunosuppressants) within 4 weeks prior to randomization * Any topical treatment of the treatment areas (except for emollients) within 2 weeks prior to randomisation. * Treatment with therapies, whether marketed or not, with a possible effect on itch within the following time periods prior to randomisation: * antihistamines - within 1 week prior to randomisation * gabapentin - within 4 weeks prior to randomisation * Subjects who have received treatment with any non-marketed drug substance (i.e. a drug 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 substance required a longer treatment free period as defined in exclusion criterion 1 for biological treatments * PUVA (Psoralen and Ultraviolet A Radiation) or Grenz ray therapy within 4 weeks prior to randomisation. * UVB therapy within 2 weeks prior to randomisation * Planned initiation of, or changes to concomitant medication that could affect psoriasis vulgaris (e.g., beta blockers, ACE inhibitors, anti-malaria drugs, lithium) within 2 weeks prior to randomisation * Subjects with current participation in any other interventional clinical trial * Subjects with any of the following conditions present on the treatment areas: viral (e.g. herpes or varicella) lesions of the skin, fungal and bacterial skin infections, parasitic infections, skin manifestations in relation to syphilis or tuberculosis, acne vulgaris, atrophic skin, striae atrophicae, fragility of skin veins, icthyosis, ulcers and wounds * Other inflammatory skin disorders (e.g. seborrhoeic dermatitis or contact dermatitis) on the treatment area that may confound the evaluation of psoriasis * Subjects with a history of serious allergy, allergic skin rash or sensitivity to any component of the investigational products or formulations being tested * Known or suspected severe renal insufficiency or severe hepatic disorders * Current diagnosis of erythrodermic, exfoliative, guttate or pustular psoriasis * Planned exposure to the sun during the study that may affect psoriasis vulgaris (i.e., normal lifestyle outdoor activities are permitted but deliberate exposure to sunlight or artificial ultraviolet light should be avoided) * Subjects previously randomised into this trial * Not all of the exclusion criteria listed due to limited space