Low-molecular-weight heparins in the treatment of deep-vein thrombosis.
OBJECTIVE
To compare the characteristics and clinical efficacy of low-molecular-weight heparins (LMWHs) and unfractionated heparin (UFH) in the treatment of deep-vein thrombosis (DVT). Adverse effects, dosing, and cost issues are also discussed.


METHODS
A MEDLINE search (January 1984-October 1997) was used to identify pertinent French and English literature, including clinical trials and reviews on LMWHs and their use in DVT.


METHODS
Trials comparing dalteparin, enoxaparin, tinzaparin, and nadroparin with UFH were selected. As studies were numerous, only randomized trials including more than 50 patients were reviewed. Moreover, all patients studied had a first episode of symptomatic DVT confirmed by objective tests (i.e., venography, duplex ultrasonography, impedance plethysmography). Clinical efficacy and safety of LMWHs were assessed in these trials.


METHODS
Results pertaining to venographic assessment, recurrent thromboembolism, total mortality, and bleeding complications were extracted from the selected studies.


RESULTS
Compared with UFH, LMWHs have a longer plasma half-life, better subcutaneous bioavailability, more predictable anticoagulant response, and require less intense laboratory monitoring. Most trials demonstrate comparable effects on thrombus extension and incidence of recurrent thromboembolism. Compared with UFH, LMWHs do not alter total mortality. Although animal trials predict a lower hemorrhagic potential for LMWHs, the incidence of bleeding complications is generally similar to that observed with UFH. Outpatient management of DVT with LMWHs has shown comparable safety and efficacy with inpatient UFH use but a shorter hospital stay.


CONCLUSIONS
Because LMWHs are as safe and as effective as UFH, and because of their more convenient method of administration, they can be considered valuable alternatives for the treatment of DVT. Savings generated by less intensive laboratory monitoring and the possibility of early hospital discharge and outpatient therapy may outweight the higher acquisition cost of LMWHs.
Martineau
P
P
Faculté de Pharmacie, Université de Montréal, Québec, Canada. martip@ere.umontreal.ca
Tawil
N
N
D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D002199:Capillary Permeability / Q000187:drug effects; D017985:Dalteparin / Q000627:therapeutic use; D017984:Enoxaparin / Q000627:therapeutic use; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D006470:Hemorrhage / Q000139:chemically induced; D006493:Heparin / Q000627:therapeutic use; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D006801:Humans; D017762:Nadroparin / Q000627:therapeutic use; D010024:Osteoporosis / Q000139:chemically induced; D016032:Randomized Controlled Trials as Topic; D013921:Thrombocytopenia / Q000139:chemically induced; D013927:Thrombosis / Q000188:drug therapy* / Q000191:economics / Q000378:metabolism; D000078222:Tinzaparin
D017984:Enoxaparin; D005343:Fibrinolytic Agents; D006495:Heparin, Low-Molecular-Weight; D017762:Nadroparin; D000078222:Tinzaparin; D006493:Heparin; D017985:Dalteparin