Clinical pharmacology of a new low molecular weight heparin (Alfa LMWH-Fluxum).
The anticoagulant effect of a Low Molecular Weight Heparin from Alfa Farmaceutici, Bologna, Italy, was studied in human volunteers of either sex. Assays of plasma anti Xa (S-2222) and anti IIa (cromozym TH) activities, and of PTT, were performed following single or repeated administration by intravenous (i.v.), subcutaneous (s.c.) or intramuscular (i.m.) route. Each set of experiments was carried out in groups of subjects ranging from 6 to 12. After i.v. adm. of 8000 and 16000 I.U. AXa peak level and half life in plasma of the anti Xa activity were about double than the corresponding values of anti IIa activity and the effect on PTT, when compared with the same reference material (heparin, Third Internat. Standard). Similar differences between these pharmacological effects were found in the response curves obtained after s.c. or i.m. adm. of 16000 and 8000 I.U. Appreciable anti Xa activity was found in plasma 16-20 hours after adm. of 16000 I.U., and 10 hours after 8000 I.U. After repeated i.m. or s.c. adm. for 7 days, no cumulative effect was observed with 16000 I.U. once daily. By giving 8000 b.i.d., mean peak levels of .35-.40 U/ml of anti Xa activity were reached in the first day and of .45-.55 U/ml in the following days, a residual activity in the order of .1-.2 U/ml being always detected in the samples drawn immediately before the following injection.