The goal of this clinical trial is to evaluate the safety and effectiveness of topical diacerein in adults with psoriasis vulgaris. The primary objective of the study is to compare the proportion of participants who achieve a clinically meaningful improvement in disease severity between the topical diacerein group and the placebo group.

Participants will:

Be assigned to receive topical diacerein 1% or placebo twice daily for a treatment period of 2 months.

Attend follow-up visits at Weeks 2, 4, 6, and 8. Undergo an additional evaluation one month after treatment cessation.

This is a phase IV, randomized, placebo-controlled, double-blind clinical study designed to evaluate the efficacy and safety of topical diacerein in adults with psoriasis vulgaris. Participants who meet eligibility criteria will be randomized to receive either topical diacerein or matching placebo. The study treatment will be applied twice daily for two months. Participants will attend follow-up visits at Weeks 2, 4, 6, and 8, during which clinical evaluations, safety assessments, and efficacy measurements will be conducted.

The primary efficacy endpoint is the proportion of participants achieving at least a 75% improvement from baseline in the Psoriasis Area and Severity Index (PASI 75) at Week 8. Secondary endpoints may include additional PASI response thresholds, investigator global assessments, patient-reported outcomes, and safety endpoints. Safety will be monitored throughout the study through the collection of adverse events, physical examinations, and other relevant clinical assessments.

Inclusion Criteria:

• Age ≥18 years old of both genders.
• Patients with mild chronic plaque psoriasis body surface area (BSA < 10%) along with Psoriasis Area and Severity Index (PASI) score of < 10, and/or Dermatology Life Quality Index (DLQI) score of <10.

Exclusion Criteria:

• Documented hypersensitivity or idiosyncratic reaction to the investigational product or any excipients contained within the cream formulation.
• Intake of anti-psoriatic systemic therapy within the last 3 months, or topical treatments within the last 2 weeks.
• Patients with pustular psoriasis.
• Pregnant and breast-feeding individuals.
• Patients with psoriatic arthritis.

A decision regarding the sharing of individual participant data (IPD) has not yet been finalized. The availability of IPD will be determined at a later date based on ethical approvals, participant consent, data protection requirements, and institutional and sponsor policies.

Participants will be randomly assigned to study groups using a computer-generated allocation sequence. Allocation concealment will be ensured through the use of sequentially numbered, opaque, sealed envelopes prepared by an independent individual and opened only after eligibility confirmation and informed consent.

The investigational product and placebo will be identical in appearance and texture and prepared by qualified study personnel. Both participants and treating clinicians will remain blinded to treatment assignment for the duration of the study.