Effect of isotretinoin on prothrombin time (PT), international normalized ratio (INR), and activated partial thromboplastin time (aPTT).

Patients with severe acne may need elective/urgent surgical interventions during treatment with isotretinoin and it is critical for the surgeon to consider the possible effects of this medication on coagulation systems. The aim of this study is to determine the changes in prothrombin time (PT), international normalized ratio (INR), and activated partial thromboplastin time (aPTT) during isotretinoin treatment. PT, aPTT, and INR values of 51 severe acne patients were evaluated during routine pre-treatment biochemical analysis. Only patients with normal values were included in the study. The results of before and after 1 month treatment were compared statistically. There were no statistically significant change in mean alanine aminotranferease (ALT), aspartate aminotransferase (AST), PT, and INR values after treatment. A significant increase in aPTT was detected. The INR values, which are more trusted and safe, showed no difference. Isotretinoin seems to have no effect on these coagulation parameters.