The FDA announced this week that it has received information about the Innohep in Renal Insufficiency Study (IRIS) that was stopped in February because of an interim finding of increased all-cause mortality in patients who received Innohep. Innohep contains tinzaparin sodium, a low molecular weight heparin that is given to patients in conjunction with warfarin sodium intravenously to treat blood clots that have occurred deep in the veins of hospitalized patients who may or may not have also experienced the occurrence of blood clots in their lungs (pulmonary embolism).
At the time the study was stopped, 350 patients had completed a 90 days of follow-up. Twenty-three out of 176 patients who received tinzaparin died, compared to nine out of 174 who received unfractionated heparin. The FDA says it sees no clear pattern as to the cause of death nor do the deaths appear to be related to either over-dosing or under-dosing of an anti-coagulant.
In July, the company revised the prescribing information to restrict the use of Innohep in patients 90 years of age and older. However, preliminary data from IRIS suggests that the increased risk of mortality is not only limited to patients in that age range. Study results suggest that compared to unfractionated heparin, Innohep increases the risk of death for patients 70 years and older with renal insufficiency and deep vein thrombosis (DVT), pulmonary embolism (PE), or both. The FDA suggests health care professionals consider the use of alternative treatments for patients older than 70 years of age with those conditions.
The FDA has requested that the labeling for Innohep be revised to better describe the overall results of IRIS. The agency anticipates final IRIS results in January 2009, and will complete its review at that time.