Effect and safety of 5% nicotinamide cream in the treatment of actinic keratosis

INTERVENTION: A randomized, double‐blind, intrasubject ,placebo‐controlled clinical trial will be conducted in which 80 immunocompetent individuals, without gender restriction, older than 18 years of age, with three to ten actinic keratoses on the forearms will be included. The 160 forearms will be randomized from computer simulation into two groups and clinically evaluated through actinic keratoses count, forearms photoaging evaluation, and actinic keratoses severity score. The actinic keratoses will be submitted to cryotherapy with liquid nitrogen, and after 14 days, according to randomization, one forearm will receive nicotinamide 5% cream and the other placebo, 2 Xa day, for 56 days. After two weeks of treatment, adverse events (skin dryness, itching, erythema, burning sensation and local irritation) and tolerability will be evaluated. After the end of the treatment (70 days after the first evaluation), the patients will undergo a new clinical evaluation (actinic keratoses count, severity score, forearm photoaging and adverse events evaluation). For each patient, the study will last 70 days, and during this time, broad‐spectrum sunscreens with sun protection factor 30 will be provided for application on both forearms. The studied area was delineated by the antecubital fossa and radiocarpal and radioulnar joints; the actinic keratoses count will be performed in duplicate, using skin marking, to ensure its reproducibility. Regarding blinding, both products will be white, of similar texture and will be packed in identical tubes and labeled only with the identification topic 1 and topic 2. All patients will be oriented by the researcher and receive a written prescription. D03.066.515.530 CONDITION: Actinic Keratosis C04.834 PRIMARY OUTCOME: An absence of new actinic keratoses on the forearms is expected after the application of 5% nicotinamide cream within a period of 70 days, which will be verified by counting the actinic keratoses, based on the verification of a variation of at least 15% in the pre and post measurements ‐intervention.; INCLUSION CRITERIA: Sign the Free and Informed Consent Form; age over 18 years of both sexes; present at least three and at most ten lesions clinically compatible with actinic keratoses on each forearm, bilaterally. SECONDARY OUTCOME: Evaluate the severity score of actinic keratoses on the forearms after the application of 5% nicotinamide cream over a period of 70 days, which will be verified through the degree of erythema, hyperkeratosis, infiltration and diameter of actinic keratoses. Each criterion is graded from zero to three. Lesions are characterized individually and values are summed. A variation of at least 15% is expected in pre‐ and post‐intervention measurements. Evaluate the side effects and tolerability of the application of 5% nicotinamide cream over a period of 70 days, which will be verified through clinical observation of edema, scaling, ulceration or blisters and the presence of symptoms of itching, burning, dryness, irritation and burning . A variation of at least 5% is expected in pre‐ and post‐intervention measurements. It is expected to find a reduction in the number of actinic keratoses on the forearms after the application of 5% nicotinamide cream over a period of 70 days, which will be verified by counting the actinic keratoses, based on the verification of a variation of at least 15% in the pre measurements and post‐intervention. ; The severity score takes into account the number of lesions, the degree of erythema, hyperkeratosis, infiltration, and the diameter (measured in millimeters) of the skin lesions. Each criterion is graded from zero to three. The lesions are characterized individually and the values are added up. It is expected to find a reduction in the photoaging scale of the forearms after the application of nicotinamide 5% cream within 70 days, which will be verified by evaluating the number of superficial and hypertrophic actinic keratoses, amount and severity of rhytids, number of sun lentigines, purpura, atrophic scars, elastosis and loss of elasticity. A change of at least 15% in pre‐ and post‐intervention measurements is expected.