Anticoagulation Patients May Need Liver Monitoring
This viewpoint offers commentary on important clinical research in the area of pharmacy.

Arora N, Gladhaber SZ
Circulation. 2006;113:e698-702

Medications that cause liver injury or acute liver failure often are marked with black box warnings and/or are removed from the market. However, drug-induced liver injury frequently is not identified until the drug has been used in a wide population of patients outside of controlled clinical trials. Recently, ximelagatran, an oral direct thrombin inhibitor, was denied US Food and Drug Adminstration approval because of concerns that it could cause liver damage and failure.

The authors of this article present 2 cases of patients receiving anticoagulant therapy who had elevated serum transaminases (case 1 -- warfarin; case 2 -- enoxaparin). In both cases, serum transaminases improved after the oral anticoagulant was discontinued. In case 1, a rechallenge with warfarin resulted in a repeat hospitalization due to worsening liver function. Although a temporal relationship between the elevated liver enzymes and the medications was apparent, a clear cause of the acute liver injury was not determined. However, the improvement in symptoms is suggestive of a causal relationship.

The authors provide a discussion of elevated serum transaminases, a review of anticoagulants and the potential for liver injury, and an outline of the diagnosis and treatment of patients with potential anticoagulant-induced liver injury. They suggest the need for further research to understand the mechanism of liver injury and an increased awareness of the potential for damage.

Drug-induced adverse effects are often difficult to identify because of confounding factors. The authors present important information that should be taken into consideration in the treatment of patients with anticoagulant therapy. The incidence of liver failure with the currently available agents may be low; however, as patients receive more complicated medication regimens that include multiple medications with hepatic metabolism, a closer evaluation of transaminases may be necessary. Pharmacists caring for such complicated patients may need to consider the incorporation of liver function monitoring into the therapeutic plan. The authors of this study suggest that consideration should be given to assessing liver function before the initiation of anticoagulant therapy in a patient with preexisting liver dysfunction.

Abstract