Use of Low Molecular Weight Heparin (Tinzaparin) to Treat Blood Clots in Patients With Kidney Failure
Information source: St. Joseph's Healthcare Hamilton
ClinicalTrials.gov processed this data on August 23, 2015 Link to the current ClinicalTrials.gov record.
Condition(s) targeted: Venous Thrombosis; Pulmonary Embolism
Intervention: Tinzaparin (Drug)
Phase: N/A
Status: Recruiting
Sponsored by: St. Joseph's Healthcare Hamilton Official(s) and/or principal investigator(s): Wendy Lim, MD, Principal Investigator, Affiliation: St Joseph's Healthcare Hamilton / McMaster University Mark A Crowther, MD, Principal Investigator, Affiliation: St Joseph's Healthcare Hamilton / McMaster University
Overall contact: Wendy Lim, MD, Phone: 905-521-6024, Email: limwp@mcmaster.ca
Summary
Blood clots in the leg veins, known as deep vein thrombosis, are important because they may
travel to the lung (known as pulmonary embolism) and cause death. Blood clots are treated
with blood thinners, or anticoagulants. The preferred treatment is an anticoagulant known
as low molecular weight heparin (LMWH). LMWH is given by an injection under the skin, which
is convenient for patients because they can self-administer this medication at home, and no
blood testing is required. However, LMWH is cleared from the body through the kidneys, so
patients who have kidney failure are generally not treated with LMWH because they may be at
a higher risk of bleeding.
One type of LMWH, known as tinzaparin, may be less dependent on the kidneys for clearance
and may not increase in patients with kidney failure. The investigators would like to use
tinzaparin to treat patients who have deep vein thrombosis or pulmonary embolism, and who
also have kidney failure.
The purpose of this study is to determine whether the blood thinning effects of tinzaparin
build up, or accumulate, in patients with varying degrees of kidney failure compared to
patients without kidney failure. The blood thinning effects will be measured using a blood
test known as an anti-Xa level. Patients will be followed over the time they receive
tinzaparin and those patients who are found to have potentially high levels of tinzaparin
(based on the anti-Xa level) will have their tinzaparin dose adjusted. The investigators
believe that the levels of tinzaparin will not accumulate to potentially dangerous levels in
a significant number of patients with kidney failure.
Clinical Details
Official title: Tinzaparin for Treatment of Venous Thromboembolism in Renal Insufficiency: A Pilot Study
Study design: Endpoint Classification: Pharmacokinetics Study, Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Treatment
Primary outcome: Anti-Xa level measured on any two of Days 3, 5 or 7 of treatment
Detailed description:
Background and rationale. Venous thromboembolism (VTE) is an important clinical problem
because it is common, preventable, contributes to morbidity and mortality, and is costly.
Low molecular weight heparin (LMWH) is the preferred anticoagulant for VTE treatment, but is
renally excreted. Consequently, LMWH use in patients with renal insufficiency may result in
accumulation of the anticoagulant effects and the potential for avoidable bleeding
complications. As a result, most patients with renal insufficiency who also have VTE are
unable to benefit from LMWH treatment. These patients are therefore generally treated in
hospital using unfractionated heparin (UFH), since it is eliminated by extra-renal
mechanisms. In addition to those patients with known renal insufficiency, many elderly
patients have previously unrecognized renal insufficiency and treatment of these patients
with LMWH can be associated with accumulation of the anticoagulant effect and avoidable
bleeding.
Tinzaparin, relative to other LMWHs, has a higher molecular weight and greater negative
charge: both biochemical features that favour non-renal clearance. There is limited
evidence to support the hypothesis that tinzaparin, unlike other LMWHs, does not accumulate
in patients with renal insufficiency. 1) Observational studies demonstrated no increase in
anti-Xa levels (i. e., no accumulation) when tinzaparin was used for VTE treatment in elderly
patients with renal insufficiency. 2) One study showed undetectable LMWH anticoagulant
activity by 24 hours after dosing in hemodialysis patients. 3) A systematic review and
meta-analysis of the literature in this area performed by our research group found no
difference in bleeding and thrombosis complication rates when LMWH (compared to UFH) was
used to maintain dialysis circuit patency in patients on hemodialysis.
The current factors which limit the use of tinzaparin in the treatment of patients with VTE
and renal insufficiency are: 1) the true risk of accumulation is unknown in a spectrum of
patients with varying renal function, and 2) the bleeding risk associated with tinzaparin
use is unknown.
Hypothesis. We hypothesize that accumulation during a 5-day course of tinzaparin will not
be related to the degree of renal insufficiency.
Study design and methods. We will perform a prospective cohort study of 200 patients with
acute VTE, stratified into 4 equal-sized groups by renal function, who will receive initial
anticoagulation with tinzaparin for 5 days concurrent with oral anticoagulants. The LMWH
anticoagulant effect will be assessed at days 3 and 5 (+/- 1) using trough anti-Xa heparin
levels. If accumulation occurs, defined as a trough anti-Xa level > 0. 5 IU/mL, the
tinzaparin dose will be adjusted according to a nomogram. Patients with an anti-Xa level ≤
0. 5 IU/mL will have no dose adjustment; patients with levels > 0. 5 IU/mL will have their
tinzaparin dose reduced.
The primary outcome of this study is the proportion of patients in each renal function group
with accumulation on or before day 5. We will follow the patients for 48 hours after their
final tinzaparin injection. Secondary outcomes are bleeding, recurrent thrombosis,
accumulation by day 3, and trough anti-Xa levels > 1. 0 IU/mL at any point in the study.
Significance. We hypothesize that tinzaparin does not accumulate in patients with renal
insufficiency. However, if accumulation occurs, we hypothesize that dose adjustment
according to our novel nomogram will prevent potentially-dangerous levels occurring by day
5. In either case, we will be able to proceed to the next stage in our research plan: an
application for funding for a large simple randomized controlled trial examining the safety
and efficacy of tinzaparin compared with UFH in patients with renal insufficiency. If
accumulation occurs despite the use of the nomogram, then this surrogate outcome suggests
that the use of therapeutic-dose tinzaparin is unlikely to be safe in patients with renal
insufficiency, a finding which will limit the need to expend further resources on this line
of research.
Eligibility
Minimum age: 18 Years.
Maximum age: 70 Years.
Gender(s): Both.
Criteria:
Inclusion Criteria:
- Adult patients 18 years of age or older
- Objectively confirmed VTE requiring anticoagulant therapy, including lower extremity
and upper extremity deep vein thrombosis (catheter and non-catheter related,
including dialysis access thrombosis [i. e., graft, fistula]); peripheral vein
thrombosis (e. g., portal vein, mesenteric vein, cerebral vein thrombosis), and
pulmonary embolism
Exclusion Criteria:
- Weight exceeding 105 kg
- Unstable declining renal function, defined as documented change in creatinine > 20%
in the past 3 months or clinical circumstances likely to be associated with change in
renal function, such as dehydration or severe intercurrent illness. Where no
previous creatinine values exist and the patient is otherwise stable, patients will
not be excluded on the basis of unknown previous renal function.
- Known allergy to heparin/LMWHs or history of heparin induced thrombocytopenia
- Treatment with UFH, LMWH, danaparoid, oral direct thrombin inhibitors for >48 h
- Bleeding requiring hospitalization or blood transfusion within 6 months(exception is
blood transfusion given in relation to surgical procedures within 6 months)
- History of intracerebral hemorrhage
- Known active liver disease (AST or ALT > 3 times the upper limit of normal, or
bilirubin > 50 umol/L)
- Known active peptic ulcer disease, with ongoing symptoms or need for anti-ulcer
medical therapy
- Thrombocytopenia (platelet count of < 100 x 109/L)
- Ongoing need for antiplatelet agents (clopidogrel, ticlopidine, aspirin > 325 mg
daily)
- Pregnancy or lactation
- Geographic inaccessibility
- Unable, or unwilling, to provide written informed consent
Locations and Contacts
Wendy Lim, MD, Phone: 905-521-6024, Email: limwp@mcmaster.ca
St Joseph's Healthcare Hamilton, Hamilton, Ontario L8N 4A6, Canada; Recruiting Wendy Lim, MD, Phone: 905-521-6024, Email: limwp@mcmaster.ca Mark Crowther, MD, Phone: 905-521-6024, Email: crowthrm@mcmaster.ca Wendy Lim, MD, Principal Investigator
Additional Information
Starting date: March 2005
Last updated: May 19, 2015
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