Large-dose infusions of heparinoid ORG 10172 in ischemic stroke

Danaparoid use for haemodialysis in a morbidly obese patient with heparin-induced thrombocytopenia - Need for a higher than recommended weight-based dosing

WHAT IS KNOWN AND OBJECTIVE

Heparin is widely used to prevent clotting of the extracorporeal circuit during haemodialysis (HD). Heparin-induced thrombocytopenia (HIT) is a potentially devastating immune mediated adverse drug reaction caused by the emergence of antibodies that activate platelets in the presence of heparin, leading to a pro-thrombotic state. Danaparoid is an alternative anticoagulant used in patients on HD with HIT but its dosing recommendations in obese patients on HD are relatively scarce.

CASE SUMMARY

We report a case of a 48-year-old morbidly obese patient who received weight-based dosing of danaparoid for HD with monitoring of anti-Xa activity. However, despite the patient's anti-Xa level being within the therapeutic range at various time points, the circuit lines kept clotting during HD.

WHAT IS NEW AND CONCLUSION

The report provides evidence that the manufacturer's recommendations on dosing danaparoid based on body weight may lead to sub-optimal therapeutic benefit and highlight the need for higher than recommended weight-based dosing in obese individuals on dialysis.

Frequency and risk factors for spontaneous hemorrhagic transformation of cerebral infarction

OBJECTIVE

Hemorrhagic transformation of cerebral infarction (HTI) occurs spontaneously but its frequency and risk factors are uncertain with mixed results in previous studies. We aimed to determine the overall frequency of and risk factors for HTI.

METHODS

We performed a systematic review according to Cochrane Collaboration methods of published reports of HTI with reliable, systematic follow-up with computed tomography or magnetic resonance imaging.

RESULTS

In all, 28 observational studies and 19 randomized controlled trials in stroke were identified that included follow-up imaging data. Problems with inconsistent definitions or small and biased patient populations limited detailed interpretation. The overall frequency of any HTI in untreated patients was 8.5% (95% confidence interval 7%-10%). Severe HTI (i.e., HTI accompanied by neurologic deterioration or parenchymal hematoma formation) occurred in 1.5% (95% confidence interval 0.8%-2.2%). The frequency of HTI increased markedly with increasing use of antithrombotic or thrombolytic drugs. Magnetic resonance imaging detected more HTI than did computed tomography. The published data were generally inadequate to undertake more detailed analysis of risk factors. However, in the 8 studies that did provide the information, HTI was associated with large infarcts, mass effect, hypodensity observed early after the stroke, and age older than 70 years, but not hypertension or cardioembolic stroke.

CONCLUSIONS

Severe HTI is uncommon in patients not receiving antithrombotic or thrombolytic agents. The methods used to assess the frequency of and risk factors for HTI, particularly a standard of definitions in future prospective studies, could be improved.

Recent advances in the acute management of ischaemic stroke

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Design of the Trial of Org 10172 in Acute Stroke Treatment (TOAST)

TOAST is a multicenter, randomized, placebo-controlled clinical trial testing the usefulness of a new antithrombotic drug in improving the outcome of persons with acute ischemic stroke. Until recently, no clinical trial testing a treatment for ischemic stroke had demonstrated efficacy in outcome. Design problems of previously conducted trials with inconclusive results may partly explain their failures. During the design of TOAST, the investigators addressed several issues so the trial could test the treatment accurately. We report the strategies used in designing, implementing, and coordinating the trial.

Danaparoid in the prevention of thromboembolic complications

OBJECTIVE

To review the therapies used to prevent postoperative thromboembolic complications with a focus on the role of danaparoid, a new low-molecular-weight glycosaminoglycan.

DATA SOURCES

A MEDLINE search was performed to identify pertinent English-language literature including studies, abstracts, and review articles. Key search terms included danaparoid, heparinoid, lomoparin, heparin, prophylaxis, thrombosis, embolism, thromboembolism, and thromboembolic and postoperative complications. The manufacturer of danaparoid was contracted for additional information related to this compound.

STUDY SELECTION AND DATA EXTRACTION

All identified articles were reviewed for possible inclusion in this review. Comparisons primarily focused on data obtained from prospective, randomized, controlled, blind clinical trials. Another important consideration was the use of venography to determine the presence of deep venous thrombosis.

DATA SYNTHESIS

Various therapies are available for the prevention of postoperative thromboembolic complications. Effective pharmacologic treatments currently available include adjusted-dose heparin, warfarin, aspirin, dextran, and low-molecular-weight heparins (LMWHs). Until recently, warfarin was considered the drug of choice for thromboprophylaxis in high-risk patients, including patients undergoing orthopedic surgical procedures. Because of their comparable efficacy and greater ease of use, LMWHs are gaining favor over warfarin in this patient population. In well-designed clinical trials involving patients undergoing elective total hip replacement or fractured hip surgery, danaparoid has demonstrated greater efficacy than other active treatments, including warfarin, dextran, aspirin, and heparin plus dihydroergotamine. While studies comparing danaparoid with LMWHs have not yet been published, danaparoid may be more useful in patients with heparin-associated thrombocytopenia.

CONCLUSIONS

Danaparoid is an antithrombotic agent with characteristics that distinguish it from heparin and LMWHs. Based on the efficacy and safety data reviewed, danaparoid should be considered one of the drugs of choice for the prevention of thromboembolic complications in patients undergoing orthopedic hip procedures and the drug of choice for the management of any patient with heparin-induced thrombocytopenia who requires anticoagulant therapy.

Low molecular weight heparin(oid)s. Clinical investigations and practical recommendations

Unfractionated heparin (UFH) is traditionally used for prevention and treatment of thrombosis. However, its use is associated with a clinically relevant bleeding risk. Low molecular weight heparin(oid) [LMWH] preparations have been designed to improve upon the efficacy and safety ratio of UFH. They have been investigated in clinical studies following the favourable outcome of extensive animal experimentation to determine their efficacy in the prevention and treatment of venous thromboembolism and in arterial thrombotic conditions such as ischaemic stroke, percutaneous transluminal coronary angioplasty (PTCA) and unstable angina. Indeed, an improved efficacy/safety ratio of LMWHs in the prevention of postoperative venous thrombosis in high risk orthopaedic surgery patients has been observed as compared to UFH prophylaxis. No significant differences with respect to antithrombotic efficacy and bleeding complications were observed in patients with relatively lower risk such as in those undergoing general surgery. Subsequently, these agents have been investigated for the treatment of venous thromboembolism. The results of a series of clinical trials reveal that LMWHs are at least as safe and effective as UFH for initial treatment, with the additional advantage of the possibility of home treatment without the requirement of laboratory control and with a reduced risk of heparin-induced thrombocytopenia. Preliminary data suggest that LMHWs may be suitable for thromboprophylaxis in neurosurgery and stroke patients; in addition, they may have a place in the treatment of patients with acute stroke, unstable angina and individuals in the post-myocardial infarction stage. However, additional confirmatory data for these potential indications are required before definite recommendations can be given. LMWH compounds have at least a similar efficacy and safety as UFH in haemodialysis. In addition, they simplify the anticoagulant regimen because of the efficacy of a single predialysis bolus injection.

Developments in antithrombotic therapy: state of the art anno 1996

This review aims to discuss recent developments in antithrombotic therapy. New and specific inhibitors of platelet dependent thrombosis appear to moderately improve the outcome in coronary vascular disease. Further studies will need to address the cost-benefit ratio of this additional intervention. Hirudin and analogues are potent inhibitors of thrombin, and are clinically efficious, but at current dosage levels still complicated by bleeding. Low molecular weight heparin have markedly improved the efficacy of prevention and treatment of venous thromboembolism.

[Treatment of cerebral ischemia in its acute phase and prospectives]

At the acute stage of cerebral ischemia, the "therapeutic window" probably does not last more than 6-12 hours. Despite similar treatments, patients admitted in stroke specialist units are more likely to survive and to have a good functional outcome than patients treated in general wards. In most cases acute arterial hypertension should not be treated. Thrombolytic agents given within 6 hours after onset, are now under evaluation in several clinical trials. There is no scientific evidence to support the use of anti-coagulation as a curative treatment of acute cerebral ischemia; however, clinical trials remain necessary, especially in progressing stroke. Neuroprotective drugs protect neurons against the consequences of hypoxia in animals: most clinical trials with oral nimodipine led to negative results but the meta-analysis suggests that patients receiving nimodipine within 12 hours after stroke onset might have a lower mortality rate and a better functional outcome. Other clinical trials with neuroprotective drugs are currently running: anti-NMDA drugs, chlomethiazol, tirilazad, ganglioside GM 1, etc Most therapeutic agents are now under evaluation. An early admission of patients with acute stroke is required to evaluate therapeutics agents which probably cannot be effective if started more than 6-12 hours after stroke onset.

Comparison of the antithrombotic effects of low molecular weight heparinoid KB-101 and heparin in a rat experimental model

1. We compared the low molecular weight heparinoid KB-101 and heparin with regard to suppression of experimental thrombus formation and effects on bleeding time, prothrombin time (PT), and activated partial thromboplastin time (APTT) in rats. 2. KB-101 exerted a similar antithrombotic activity as that of heparin. 3. Heparin prolonged bleeding time, PT, and APTT more than KB-101 did. 4. These results suggested that KB-101 is superior to heparin as an anticoagulant.

Hospital arrival time after onset of stroke

To estimate the proportion of patients with stroke likely to be eligible for a trial of anticoagulant treatment for acute ischaemic stroke, the interval between onset of symptoms and arrival at hospital was analysed prospectively. Of 773 patients with stroke admitted in one year, 63% arrived at hospital within 12 hours, 76% within 24 hours, and 85% within 48 hours of ictus. The arrival time varied significantly with stroke subtype. Patients with intracerebral haemorrhage tended to arrive earlier than those with cerebral infarct, who arrived sooner than those with lacunar infarct. The results suggest that about half of all patients with ischaemic stroke in Hong Kong would present within 12 hours of ictus, in time for inclusion in a therapeutic trial.