When Anticoagulants Go Head-to-Head

Tinzaparin versus warfarin for blood clot treatment in cancer patients

(RxWiki News) When two medications have the same effect, a head-to-head trial is often the best way to see which one is more effective.

A recent study from Canada compared the injected anticoagulant medication tinzaparin (brand name Innohep) with the oral anticoagulant medication warfarin (Coumadin). Both treatments were found to be effective, but cancer patients on tinzaparin were less likely to have bleeding — a side effect of treatment.

“Tinzaparin is one of many low molecular weight heparin medications that have been studied for the treatment of blood clots," said David Winter, MD, chief clinical officer, president and chairman of the board of Baylor Health Care System's HealthTexas Provider Network, in an interview with dailyRx News. "All have been shown to be of benefit but have the disadvantage of requiring injection for administration. Oral medications that work by a different mechanism are also available to treat blood clots. Head-to-head comparisons are sparse and the optimal treatment has yet to be determined.”

A blood clot, also known as a venous thromboembolism (VTE), is a serious side effect of cancer and cancer treatment. A clot in the veins can break off and be carried to the heart or lungs, which can cause life-threatening complications.

Tinzaparin and warfarin help keep the blood from clotting, but unexpected or excessive bleeding is a possible side effect.

Cancer patients on anticoagulants need regular lab tests to determine if their blood is in the right range.

Agnes Y. Y. Lee, MD, of the University of British Columbia at Vancouver, led this study, which looked at 900 patients with active cancer and documented VTE.

Dr. Lee and team randomly divided the patients into two groups.

The first group was given tinzaparin daily for six months. The second group was given tinzaparin for five to 10 days, and then warfarin for six months.

The tinzaparin-only group was found to be less likely to have bleeding. However, neither drug regimen changed patients' overall death rate or the rate of developing major bleeding.

The tinzaparin-only group also had a significantly lowered risk of recurrent VTEs. In the tinzaparin-only group, 7.2 percent of patients developed another VTE — while 10.5 percent developed another in the tinzaparin plus warfarin group.

"Together with the adverse events data, [this trial] demonstrated that tinzaparin, even when given at a full therapeutic dose for up to six months, is safe in a broad oncology population," Dr. Lee and colleagues wrote. "Further studies are needed to assess whether the efficacy outcomes would be different in patients at higher risk of recurrent VTE."

This study was published in the August issue of JAMA.

LEO Pharma, the Sondra and Stephen Hardis Endowed Chair in Oncology Research and the Scott Hamilton CARES Initiative funded this research.

Several study authors disclosed funding from companies that make drugs used in VTE or cancer treatment.

Review Date: 
August 17, 2015