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Deep vein thromboses (DVT), which are serious because of their associated risk of pulmonary embolism and troublesome due to the possible development of a post-phlebitic syndrome, require rigorous management. However, the diagnosis is facilitated by Doppler ultrasound and treatment by low molecular weight heparins (LMWH) is simple to administer and follow. It is therefore logical to propose out patient treatment, provided certain rigorous rules are respected: establishment of an objective diagnosis of DVT, as the clinical signs are relatively nonspecific, admission to hospital of patients with a haemorrhagic risk or presenting a contraindication to anticoagulants, extensive DVT (extending beyond the mid-femoral zone), floating thrombus, patients with moderate signs may suggest pulmonary embolism. The recommended dosage for LMWH is 100 IU/kg twice a day (s.c.) (or 175 IU/kg once a day for the LMWH most recently available in France) which must be followed by oral anticoagulants for 5 months (aspirin is not sufficiently effective). Contention and rigorous clinical follow-up are obviously essential. The management of DVT is fascinating and requires coordination of several competent specialists.

Hirudin is a potent and specific thrombin inhibitor: compared with heparin thrombin inhibition occurs directly and does not require the presence of plasma cofactors. Recombinant hirudin is well tolerated in animals and in healthy volunteers. Its clearance half-life after IV administration range from 1 to 2 hours and its bioavailability after subcutaneous administration reaches 75%. In most of the experimental models the ratio of the haemorrhagic side effect against the antithrombotic efficacy is satisfactory. Hirudin analogs are mono or bivalent according to their recognition site on thrombin. Bivalent derivatives (Hirulogs) have been mostly evaluated: they exhibit pharmacologic properties similar experimental to that of recombinant hirudin and have been successfully used in several thrombosis models and in healthy volunteers. Taking into account these data the most appropriate use for hirudin and hirudin derivatives should be clinical situations where the role of thrombin is important or which are only partially controlled by heparin therapy.