Summary
The effect of isotretinoin on fibrinolysis was investigated in 10 healthy, male volunteers
in a randomized, double-blind, crossover-designed study. Isotretinoin (40 mg) was
administered in the morning and in the evening for 5 days. t-PA, u-PA and PAI-1 antigen
and activity in plasma 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 significant stimulatory
effect on endogenous t-PA antigen and activity in morning 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
higher during isotretinoin than during placebo treatment. After treatment with isotretinoin
a significant rise of fasting triglyceride plasma levels was observed as compared
to placebo. The study shows that isotretinoin has no clinically significant effect
on endogenous fibrinolysis.
