Isotretinoin effect on the repair of bone defects - a study in rat calvaria.
Isotretinoin is a vitamin A derivative, indicated for the treatment of patients with severe acne, which shows several side effects on bone metabolism. This study analyzed the process of bone repair in rats receiving 7.5 mg/kg/day of oral isotretinoin. Thirty-three male albino Wistar rats, at approximately 60 days of age, were randomly assigned to control (n = 15) and experimental (n = 18) groups. Only the experimental group underwent oral isotretinoin therapy. In both groups, a 2-mm cavity was established in the calvarium of each animal. The animals were euthanize 21, 28 and 90 days postoperatively. The parietal bone was removed and the surgical specimens underwent histological examination. Computed histomorphometry allowed the measurement of the total area of bone defects and the proportion of newly formed bone at the different observation time points. In the experimental group, the results, expressed as mean percentage of newly formed bone, were: 25.37% (±9.14) at day 21; 41.78% (±7.00) at day 28; and 57.51% (±11.62) at day 90. In the control group, the results were: 17.10% (±9.23) at day 21; 34.42% (±7.70) at day 28; and 48.49% (±16.40) at day 90. These results enabled us to conclude that isotretinoin promoted acceleration in the process of new bone formation in rat calvaria, although this increase was not statistically significant.