Background The efficacy of conventional isotretinoin treatment (0·5–1·0 mg kg−1 daily for 16–32 weeks, reaching a cumulative dose of 120 mg kg−1) for acne has been well established. To date, there are many reports regarding the efficacy of low-dose and intermittent isotretinoin treatment in patients with acne. Data comparing these three therapeutic regimens simultaneously, however, are unavailable.
Objectives To evaluate the clinical efficacy and tolerability of low-dose and intermittent isotretinoin regimens and to compare them directly with conventional isotretinoin treatment.
Methods In this study, 60 patients with moderate acne were enrolled and randomized to receive either isotretinoin at 0·5–0·7 mg kg−1 daily (group A), isotretinoin at 0·25–0·4 mg kg−1 daily (group B) or isotretinoin at 0·5–0·7 mg kg−1 daily for 1 week out of every 4 weeks (group C). The total period of drug administration was 6 weeks in group C, and 24 weeks in groups A and B. Evaluations included global acne grading system (GAGS) scores, lesion counts (inflammatory and noninflammatory), patient satisfaction and side-effects. A 1-year follow-up evaluation after the end of treatment was also performed.
Results Differences in GAGS scores were statistically significant between groups A and C (P < 0·001) and groups B and C (P = 0·044). There was no significant difference between groups A and B. For the number of inflammatory lesions, there were statistically significant differences between groups B and C (P = 0·048) and groups C and A (P = 0·005). There was no significant difference between groups A and B. For the number of noninflammatory lesions, there were statistically significant differences between groups B and C (P = 0·046) and groups C and A (P = 0·006). There was no significant difference between groups A and B. These results suggest that the conventional and low-dose regimens have similar efficacy. Intermittent treatment had less effect than either conventional or low-dose treatments. Patient satisfaction was highest in group B (3·76), followed by group C (3·31), then A (3·06), with statistically significant differences between groups A and B (P = 0·003) and groups B and C (P = 0·019) but no significant difference between groups A and C. This result suggests that the low-dose regimen is superior to other regimens (conventional or intermittent) in terms of patient satisfaction. Side-effects were more frequent with conventional treatment compared with low-dose and intermittent treatments. One year after the end of treatment, two of 16 patients relapsed in group A, three of 17 patients relapsed in group B, and nine of 16 patients relapsed in group C.
Conclusions Our study suggests that, when considering tolerability, efficacy and patient satisfaction, low-dose treatment is most suitable for patients with moderate acne.