This study was designed to assess the phototoxic potential of diacerein 1% ointment when application is followed by light exposure.

This was a single-center, randomized, within-subject comparison of diacerein 1% ointment and vehicle ointment applied to 2 sites on opposite sides of the the infrascapular area of the back under occlusive patch conditions for approximately 24 (±2) hours. Product was applied according to the randomization scheme in an amount of 0.2 mL, once during the study.

Patches were removed and 1 of the skin sites for each product was irradiated and 1 remained non-irradiated. The irradiated and non-irradiated sites were compared with each other and with an untreated irradiated control site.

Key Inclusion Criteria:

• Is a healthy male or female (to be confirmed by medical history);
• Is 18 years of age or older;
• In the case of a female of childbearing potential, is using two acceptable forms of birth control;
• In the case of a female of childbearing potential, has a negative urine pregnancy test (UPT) at Day 1 and are willing to submit to a UPT at the end of study (EOS);
• Is free of any systemic or dermatological disorder, which, in the opinion of the Investigator, will interfere with the study results or increase the risk of adverse events (AEs);
• Is of any Fitzpatrick Skin Type or race, providing the skin pigmentation will allow discernment of erythema

Key Exclusion Criteria:

• Has a history of photosensitivity or photoallergy;
• Has any visible skin disease at the application site which, in the opinion of the Investigator, will interfere with the evaluation of the test site reaction;
• Is using systemic/topical corticosteroids within 3 weeks prior to and/or during the study, or systemic/topical antihistamines 72 hours prior to and during the study;
• Is not willing to refrain from using systemic/topical anti-inflammatory analgesics such as aspirin (occasional use of acetaminophen will be permitted);
• Is taking medication known to cause phototoxic reactions (eg, tetracyclines, thiazides, nonsteroidal anti-inflammatory drugs [NSAIDs]);
• Has psoriasis and/or active atopic dermatitis/eczema;
• Has known sensitivity or allergy to constituents of materials being evaluated including diacerein, mineral oil, petrolatum, cetyl alcohol, D&C Yellow #10 and/or ethyl paraben;
• Has damaged skin in or around the test sites, including sunburn, excessively deep tans,uneven skin tones, tattoos, scars, excessive hair, numerous freckles, or other disfigurations of the test site;
• Has received treatment for any type of internal cancer within 5 years prior to study entry;
• Has any known sensitivity to adhesives; and/or
• Has received any investigational drug(s) within 4 weeks prior to study entry

Adverse Events (AEs) were to be reported from first dose through completion of the last study visit (i.e. Four days).

Adverse events were not assessed at a patch site-specific level.

There were no limitations or caveats in this trial.