Topical isotretinoin vs. topical retinoic acid in the treatment of acne vulgaris
Authors: Domínguez Judith , Hojyo María Teresa , Celayo José Luís , Domínguez‐Soto Luciano , Teixeira Fernanda 
Published: March 2003

This is a clinical, prospective, and longitudinal study comparing the efficacy and incidence of averse effects of topical isotretinoin against those of topical retinoic acid in the treatment of acne vulgaris. The 30 participants were recruited from the patients attending the outpatient clinic of the Department of Dermatology of “Dr Manuel Gea González” General Hospital in Mexico City. They belonged to either sex and any race, their ages ranged between 13 and 30 years, and they presented with 15 to 100 facial inflammatory lesions (papulo‐pustules) and/or 15 to 100 noninflammatory lesions (comedones) and no more than three nodulo‐cystic lesions. The criteria of exclusion were as follows: pregnancy or lactation, systemic treatment with steroids, antibiotics, antiandrogens, or oral retinoids in the preceding 24 months, treatment with ultraviolet radiation, hypersensitivity to retinoids, or a severe systemic illness. From 44 interviewed patients, 14 were excluded. A detailed clinical history was obtained from the remaining individuals, the degree of seborrhea was recorded, and acne lesions were counted. Each patient received either isotretinoin gel 0.05% or retinoic acid cream 0.05%. The patients were instructed to wash their faces in the mornings and evenings with a neutral soap, and to apply the product after the evening cleansing.

The patients were examined again after 2, 4, 8, and 12 weeks of treatment and, at each appointment, the number of lesions was recorded and the severity of acne was graded according to the classification of Plewig and Kligman.1 The seriousness of the adverse effects, such as stinging, pruritus, erythema, xerosis, and desquamation, was evaluated blindly by an investigator who did not know what group the patient belonged to, and graded as 1=mild, 2=moderate, and 3=severe.

The efficacy of each drug was determined by the reduction in the number of lesions between weeks 0 and 12 of treatment. An excellent response corresponded to a 76%–100% reduction of the lesions, a good response to a 51%–75% reduction, a fair response to a 26%–50% reduction, and a poor response to a 0%–25% reduction. The results were analyzed statistically using the chi‐square test, the exact test of Fisher and the test of Wilcoxon–Mann–Whitney. The changes in the numbers of lesions between weeks 0 and 12 were analyzed separately for each group of treatment, and the level of statistical significance was fixed at 0.05. The analysis was performed with the aid of a Stat program, version 4.0.

Results The patients were assigned randomly to either Group I (isotretinoin) or Group II (retinoic acid). Each group was composed of 15 individuals and, as a coincidence, in each group there were nine women and six men. The clinical differences between the groups at the first visit were not statistically significant.

In both groups, there was, in general, a good response to treatment (Fig. 1). Both drugs had a similar degree of efficacy on inflammatory lesions. At the first visit, grades III and IV predominated, whereas, after 12 weeks of treatment, most patients were classified in grades I or II (Fig. 2). Similar results were observed regarding noninflammatory lesions (Fig. 3).

Ten of the patients of Group II complained of stinging associated with the treatment, especially at weeks 8 and 12, as well as erythema and desquamation at the 12th week. Erythema and stinging lasted for minutes or hours, whereas desquamation persisted for several days. Seven individuals receiving isotretinoin mentioned irritation, which was of a mild degree.