Initiating warfarin therapy

Considerations for Systemic Anticoagulation in ESRD

In the setting of end-stage kidney disease, the incidence and risk for thrombotic events are increased and use of anticoagulants is common. The incidence of bleeding, however, is also a frequent issue and creates additional challenges in the management of anticoagulation therapy. Patients with end-stage renal disease are typically excluded from large clinical trials exploring the use of anticoagulants, which limits our knowledge of optimal management approaches. Furthermore, varying degrees of renal failure in addition to conditions that alter the pharmacokinetics of various anticoagulants or pharmacodynamic response may warrant alternative approaches to dosing. This review will explore systemic chronic anticoagulation therapy in the setting of chronic kidney disease where hemodialysis is required. Agents discussed include vitamin K antagonists, low-molecular-weight heparins, fondaparinux, oral factor Xa antagonists, and direct thrombin inhibitors. Clinical challenges, approaches to dosing regimens, and tools for measuring responses and reversal will be explored.

Systemic anticoagulation considerations in chronic kidney disease

Anticoagulation therapy is commonly required in patients with chronic kidney disease for treatment or prevention of thromboembolic disorders. Anticoagulant management plans can involve use of a single agent, or in some cases, a combination of agents to meet both short- and long-term goals. Systemic anticoagulation in the setting of renal insufficiency poses unique challenges secondary to renal failure-associated hypercoagulable conditions and increased risks for bleeding. Evidence supporting dosing regimens and monitoring approaches in the setting of severe renal impairment or hemodialysis is limited because this population is typically excluded in clinical trials. This review explores concepts of systemic anticoagulation in the chronic kidney disease setting with warfarin, unfractionated heparin, low-molecular-weight heparin, fondaparinux, direct thrombin inhibitors, and anticoagulants in advanced stages of development. Potential strategies for anticoagulant reversal are also briefly described.

Assessing Anticoagulation Knowledge in Patients New to Warfarin Therapy

Background:

Warfarin is highly efficacious for the treatment and prevention of thromboembolic disorders. However, anticoagulation control has been a longstanding challenge, as patients' lack of knowledge of warfarin therapy is a predictor of nonadherence and compromised patient safety.

Objective:

To ascertain whether hospitalized patients newly initiated on warfarin are provided adequate anticoagulation education during hospitalization, as measured at discharge, as well as determine whether there is a difference in the knowledge obtained by patients educated via a structured program versus those counseled by “usual care.”

Methods:

A prospective evaluation of warfarin education of inpatients new to warfarin therapy was performed at Bassett Medical Center, Cooperstown, NY. Patients who were admitted to the hospital and receiving warfarin for any given diagnosis, were >18 years of age and able to give informed consent, and spoke English were recruited. Patients with dementia or cognitive impairment, those who were pregnant, or those who had previously been on warfarin therapy were excluded. Recruited patients received warfarin education in the form of a structured program provided by a pharmacist or counseling by usual care during hospitalization. Prior to discharge, the Oral Anticoagulation Knowledge (OAK) test, a prevalidated tool used to measure warfarin knowledge, was administered to evaluate outcomes. Further warfarin education was provided post-test if necessary.

Results:

The intervention group (n = 20) scored significantly higher on the OAK test than the usual care group (n = 20): 74% versus 55%, respectively (p = 0.004).

Conclusions:

This preliminary study demonstrated that there is a large amount of variability regarding patient knowledge of warfarin on discharge from an inpatient facility. A formalized inpatient warfarin education program may empower patients to achieve a larger degree of initial warfarin knowledge than those educated by usual care. Previous studies have demonstrated that this may improve adherence and subsequently increase long-term safety associated with oral anticoagulation. Larger, prospective, randomized studies are necessary to further evaluate patient education and safety outcomes.

Practical application of the 10-mg warfarin initiation nomogram

Initiation of warfarin therapy is a clinical challenge. A 10-mg warfarin initiation nomogram was recently validated in a randomized controlled trial. We sought to determine the efficacy and safety of this 10-mg warfarin initiation nomogram in 'real-life' daily practice. A retrospective cohort including all outpatients beginning concurrent treatment with warfarin and low-molecular-weight heparin over a 24-month period in our Thrombosis Unit was reviewed. Eight hundred and forty-one patients were included; of them, 640 (76.1%) were started on the nomogram. The nomogram was entirely followed in 324 patients (38.5%). The efficacy and safety profile was similar to that observed in the original clinical trial; 86% of patients managed according to the nomogram reached the international normalized ratio target of 2.0-3.0 within 5 days. Mean duration of low-molecular-weight heparin treatment was 6.0 +/- 1.9 days, and 3.7% of patients had an international normalized ratio of at least 5.0 in the first 4 weeks of treatment. The 10-mg nomogram effectively results in an early therapeutic international normalized ratio with a good safety profile in 'real-life' daily practice.

Implementing anticoagulation management by pharmacists in the inpatient setting

PURPOSE

This article identifies approaches for implementing an inpatient anticoagulation program involving pharmacists; two successful inpatient anticoagulation programs previously reported in the literature are described with a discussion of steps to consider in developing or expanding such a service.

SUMMARY

Two institutions implemented pharmacist-managed anticoagulation services. One institution identified an undesirable incidence of medication-related adverse events occurring in hospitalized patients receiving anticoagulants. Pharmacists were asked to assist. Pharmacist activities included the selection of anticoagulants, patient education, verification of insurance coverage of the patient's anticoagulant, and coordination of follow-up. Physicians were available to assist. At the other institution, the department of pharmacy was asked by the orthopedic surgeons to manage warfarin for the prophylaxis against venous thromboembolism. The pharmacy department worked with the medical staff to gain approval of all policies, guidelines, and protocols to establish an anticoagulation service. Because of the success of the program, the pharmacy department expanded the service beyond warfarin. The steps to establishment of an anticoagulation service are described. The challenges facing such programs are discussed, including the potential anticoagulants in development that will create ongoing challenges in deciding which anticoagulation approach to use and in identifying patients for whom the newer agents may or may not be best suited.

CONCLUSION

Requirements for establishing a successful inpatient anticoagulation management program included defining the pharmacist's role in identifying patient needs, gaining support from other health care professionals, designing a program that addresses the needs of the patients, and managing unanticipated issues.

Ximelagatran: a new antithrombotic option in atrial fibrillation

Treatment strategies in patients with atrial fibrillation typically involve pharmacologic or interventional invasive therapies to suppress the rhythm, control ventricular contraction rates, or prevent thromboembolic complications. Current therapies used for rhythm conversion in atrial fibrillation may have undesirable risks or side effects that limit this approach. Lifelong anticoagulation may be necessary to prevent the formation of thrombus in the left atrial chamber that can travel into the cerebral circulation to cause a stroke. Currently, warfarin is the most commonly prescribed anticoagulant for this purpose. Unfortunately, many patients with atrial fibrillation may not receive warfarin because of the difficulties in dosing and maintaining desirable target goals. The oral direct thrombin inhibitor ximelagatran has several pharmacologic properties that provide a unique and potentially desirable treatment option. Clinical studies have demonstrated that ximelagatran, administered in twice-daily doses of 36 mg, is non-inferior to warfarin for thromboprophylaxis against stroke or systemic embolism in atrial fibrillation. The pharmacology of ximelagatran and clinical trials with its use in atrial fibrillation is reviewed.

Ximelagatran: an oral direct thrombin inhibitor

OBJECTIVE

To present the chemistry, pharmacology, and pharmacokinetics of ximelagatran, an oral direct thrombin inhibitor (DTI), and to review available comparative clinical trial data evaluating its efficacy and safety relative to other antithrombotic agents in the prevention and treatment of thromboembolism.

DATA SOURCES

A search of the PubMed and Cochrane databases (1995-August 2004), supplemented by a manual search of article bibliographies, conference abstracts, and data on file from the manufacturer, was conducted. Key search terms were ximelagatran, melagatran, H376/95, and direct thrombin inhibitors.

STUDY SELECTION AND DATA EXTRACTION

Pertinent information from available clinical trials, including study design, patient demographics, dosing regimens, anticoagulant comparators, methods for evaluating effectiveness, treatment outcomes, adverse events, and pharmacokinetic and pharmacodynamic evaluations, was extracted.

DATA SYNTHESIS

Ximelagatran is an orally administered DTI under development for use in the treatment of venous thromboembolism (VTE), long-term prevention of a second VTE event, stroke secondary to atrial fibrillation, prevention of VTE after orthopedic procedures, and recurrent ischemic events after acute myocardial infarction.

CONCLUSIONS

Ximelagatran, in twice-daily doses of 24 or 36 mg, is an alternative to low-molecular-weight heparins or warfarin in thromboprophylaxis following orthopedic knee replacement, atrial fibrillation, or initial treatment of VTE. Improved outcomes versus placebo were seen in the long-term prevention of VTE in patients who completed an initial 6 months of treatment. Liver-related effects need further clarification.