coagulation counseling

Anna D. Garrett, PharmD, BCPS, CPP
Published Online: Tuesday, January 1, 2008

Dr. Garrett is a clinical pharmacist practitioner at Cornerstone Health Care in High Point, NC.


USE OF HEPARIN REDUCES RATE OF CATHETER-RELATED INFECTIONS

Catheter-related infection (CRI) is the most common life-threatening complication of central venous catheter placement. More than 200,000 cases are reported annually in the United States. Catheters are the most common cause of bloodstream infection and are associated with substantial excess in mortality, length of hospital stay, and cost.

Experimental studies suggest a close relationship between catheter thrombosis and infection. Several proteins found in clots are able to increase adherence of staphylococci and Candida species to catheters. Previous studies have demonstrated that a fibrin sheath surrounding the catheter greatly enhances catheter colonization. Animal studies have shown that subcutaneous enoxaparin, a low-molecular-weight heparin, is able to decrease the fibrin-sheath formation and the incidence of catheter colonization by Staphylococcus epidermidis.

Recent clinical trials suggest that heparin could reduce catheter-related bloodstream infections. A randomized double-blind study in critically ill children has shown that heparin-bonded catheters reduce thrombosis and positive blood cultures (drawn through the catheter). A significant decrease in CRI has also been demonstrated in bone marrow transplant patients who were given low daily doses of heparin. No adverse effects of heparin were noted in either study. These results, which need to be confirmed in larger studies, suggest that heparin may provide a low-cost method of reducing the incidence of a very expensive complication of catheter use.


EPTIFIBATIDE MAY HELP SICKLE-CELL PATIENTS

Researchers at the University of North Carolina have published results of a small study using eptifibatide (Integrilin; Schering-Plough) to treat sickle cell disease. Sickle cell disease, an inherited disorder, causes malformations in red blood cells that cause painful episodes (crises) when they block blood vessels. Hydroxyurea is the only medication currently approved to treat sickle cell disease.

A small phase 1 study done at the University of North Carolina evaluated the effect of eptifibatide on platelet aggregation and CD40 ligand (CD40L), both of which are thought to play a role in sickle cell crisis. The study included 4 patients who were not in an acute pain crisis. They were given intravenous infusions of eptifibatide, which is most commonly used in acute coronary syndrome (ACS) and during coronary stent placement. No patients experienced a pain crisis during the study. Decreases in platelet aggregation and CD40L were similar to those observed in ACS. Further study will be required in larger numbers of patients before eptifibatide can be recommended as a treatment for sickle cell disease.


HIGHER DOSE OF CLOPIDOGREL CUTS RISK OF CORONARY EVENTS

Pretreatment with a double dose of clopidogrel just before percutaneous coronary intervention (PCI) cuts the combined risk of heart attack and cardiac death by half, according to a new study. Researchers found that giving patients at least 600 mg of clopidogrel before stenting, rather than the standard 300-mg dose, halved the risk of major complications associated with thrombosis. The higher dose did not increase the risk of serious bleeding.

The research, which was a meta-analysis of data from 10 studies, included more than 1500 patients. Overall, pretreatment with high-dose clopidogrel (600 mg or more) was associated with a 50% reduction in the risk of cardiac death or nonfatal heart attack, both during the initial hospitalization and within 30 days of the PCI procedure, a finding that was very statistically significant. There was no statistically significant increase in major or minor bleeding. Findings remained the same when the analysis was restricted to randomized controlled trials only. Subanalysis showed that the higher the underlying risk of complications related to blood clotting, the greater the benefit from high-dose clopidogrel.


VITAMIN E LOWERS THROMBOSIS RISK

A recently published study found a decrease in the risk of venous thromboembolism (VTE) in women who received vitamin E supplementation. In this randomized, placebo-controlled study, 39,876 women aged 45 or older received a supplement of 600 IU of natural source vitamin E on alternate days.

During the 10-year study, VTE occurred in 482 women (213 in the vitamin E group, 269 in the placebo group). This represented a 21% hazard reduction. For unprovoked VTE, the reduction was 27%. In subgroup analyses, the 3% of participants who reported VTE before randomization had a 44% hazard reduction, whereas women without prior VTE had an 18% reduction. Women with either factor V Leiden or the prothrombin mutation had a 49% hazard reduction with vitamin E treatment. The researchers concluded that supplementation with vitamin E may reduce the risk of VTE in women, particularly those with a prior history of VTE or a genetic predisposition.



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