Parnaparin is a low molecular weight (LMW)
heparin which, like other members of its class, apparently demonstrates a greater antithrombotic effect relative to its
anticoagulant activity when compared with the
unfractionated heparin (
heparin) from which it is derived. Moreover, subcutaneous
parnaparin has a greater bioavailability and longer half-life than
heparin, permitting once-daily administration for the prophylaxis of
deep venous thrombosis (DVT) or the treatment of established vascular disorders. Prophylaxis with a 7-day regimen of
parnaparin 3200 or 6400 IUaXa/day has consistently been associated with a lower incidence of confirmed DVT compared with usual prophylactic regimens of
heparin. This intertreatment difference reached statistical significance in a large multicentre study involving a total of 610 surgical patients (3.2% for
parnaparin vs 6.3% for
heparin). Thus far, however, comparisons of
parnaparin with other LMW heparins for this indication are unavailable.
Parnaparin has demonstrated equivalent efficacy to
heparin in the treatment of established vascular disorders, including phlebopathies and related syndromes, as well as
peripheral arterial occlusive disease.
Parnaparin also showed some benefit as an adjunctive
therapy in patients with
angina pectoris. The risk of general
bleeding appears to be similar with
parnaparin or
heparin, although
parnaparin results in fewer haematomas at the site of injection, partly because of the less frequent administration regimen.
Parnaparin has also been associated with a lower incidence of
pain and/or burning sensation at the injection site compared with
heparin. As with other LMW heparins, the possibility that
parnaparin will be infrequently associated with
thrombocytopenia cannot be excluded. Thus,
parnaparin may be preferred over traditional
heparin for the prophylaxis of thromboembolic events in surgical patients (particularly those at high risk for DVT), as well as the treatment of established vascular disorders with a thrombotic aetiology. Compared with
heparin,
parnaparin offers the advantages of a more convenient administration regimen coupled with improved local tolerability. However, the therapeutic advantages of
parnaparin relative to other LMW heparins have yet to be established in large scale comparative trials.