EFFECT OF ISOTRETINOIN ON ENDOGENOUS TISSUE-TYPE PLASMINOGEN-ACTIVATOR (T-PA) AND PLASMINOGEN-ACTIVATOR INHIBITOR-1 (PAI-1) IN HUMANS

The effect of isotretinoin on fibrinolysis was investigated in 10 heal thy, male volunteers in a randomized, double-blind, crossover-designed study. Isotretinoin (40 mg) was administered in the morning and in th e evening for 5 days. t-PA, u-PA and PAI-1 antigen and activity in pla sma were measured every morning at 9 a. m. on days 1 to 4 and every 3 hours over 24 hours on day 5. Isotretinoin treatment had no significan t stimulatory effect on endogenous t-PA antigen and activity in mornin g plasma samples nor on their circadian variation. Also, u-PA antigen levels did not change after isotretinoin treatment. Mean PAI-1 antigen and PAI activity in 9 a.m. plasma samples were non-significantly high er during isotretinoin than during placebo treatment. After treatment with isotretinoin a significant rise of fasting triglyceride plasma le vels was observed as compared to placebo. The study shows that isotret inoin has no clinically significant effect on endogenous fibrinolysis.