Heparin-induced
thrombocytopenia (HIT), a serious side effect of
heparin treatment, requires alternative anticoagulation in most affected patients. The recombinant
hirudin (r-
hirudin)
lepirudin has been approved for this purpose after two prospective trials in laboratory-confirmed HIT patients. Other drugs available for this purpose are
danaparoid sodium (a
heparinoid) and
argatroban, a synthetic
direct thrombin inhibitor. In this article, recommendations for optimal use of r-
hirudin in HIT are given, covering
therapy in uncomplicated patients as well as in special situations such as
heparin reexposure of HIT patients. Because
lepirudin's half-life depends on renal function, it may vary between 1 and 200 hours, which requires individual dose adjustments.
Lepirudin compares favorably with
danaparoid, based on retrospective data. No direct comparisons of
lepirudin with
argatroban are available, but
argatroban might offer advantages in patients with
renal failure, because it is mainly eliminated hepatically. Major
hemorrhage, the main risk of
lepirudin treatment, occurring in about 15% of patients, makes close monitoring important. New monitoring tools, such as the
ecarin clotting time (ECT), might further reduce
bleeding risks. Antihirudin
antibodies, which can alter the pharmacokinetics as well as the pharmacodynamics of
hirudin, can also be countered by close monitoring and appropriate dose adjustments. Whereas
hirudins have not yet managed to gain importance in non-HIT indications such as unstable coronary syndromes, they have a major role to play in the treatment of HIT. The choice between the available drugs for HIT, namely
lepirudin,
danaparoid, and
argatroban, has to be made according to the clinical presentation of the patient.