Old and new anticoagulant drugs: a minireview

Efficacy and Safety of Direct Oral Anticoagulants in Stable Coronary Artery Disease and Atrial Fibrillation: A Systematic Review and Network Meta-Analysis

Direct Oral Anticoagulants (DOACs) , which partially replace warfarin, have been developed as a safe and effective therapy for patients with stable coronary artery disease (SCAD) and atrial fibrillation (AF). However, the choice of DOACs and warfarin remains controversial. We conducted a network meta-analysis (NMA) using randomized controlled trials (RCTs) through a systematic literature review to evaluate the the efficacy and safety of DOACs in SCAD and AF patients. Five RCTs with 6524 patients were included. The results showed that patients taking DOACs had a lower risk of stroke/systemic embolism (OR, 0.64; 95% CI, 0.54-0.76, P < .00001, I2 = 89%), intracranial bleeding (OR, 0.41; 95% CI, 0.26-0.64, P = .0001, I2 = 0%), major bleeding (OR, 0.98; 95% CI, 0.81-1.148, P = .80, I2 = 88%), and all-cause mortality (OR, 1.04; 95% CI, 0.88-1.22, P = .66, I2 = 51%) than those taking warfarin. Compared to warfarin, rivaroxaban (20 mg, once/day) was more advantageous in preventing stroke/systemic embolism, as was apixaban (5 mg or 2.5 mg, twice/day) in reducing major bleeding (OR, 0.79; 95% CI, 0.48-1.3) and all-cause mortality (OR, 0.97; 95% CI, 0.69-1.4). Different doses of DOACs showed obvious advantages against intracranial hemorrhage, without significant differences. Thus, DOACs have more effective than warfarin in clinical efficacy and safety.

Smart Responsive Microarray Patches for Transdermal Drug Delivery and Biological Monitoring

Traditional drug delivery routes possess various disadvantages which make them unsuitable for certain population groups, or indeed unsuitable for drugs with certain physicochemical properties. As a result, a variety of alternative drug delivery routes have been explored in recent decades, including transdermal drug delivery. One of the most promising novel transdermal drug delivery technologies is a microarray patch (MAP), which can bypass the outermost skin barrier and deliver drugs directly into the viable epidermis and dermis. Unlike traditional MAPs which release loaded cargo simultaneously upon insertion into the skin, stimuli responsive MAPs based on biological stimuli are able to precisely release the drug in response to the need for additional doses. Thus, smart MAPs that are only responsive to certain external stimuli are highly desirable, as they provide safer and more efficient drug delivery. In addition to drug delivery, they can also be used for biological monitoring, which further expands their applications.

Effect of anticoagulants on fibrin clot structure: A comparison between vitamin K antagonists and factor Xa inhibitors

BACKGROUND

Abnormal clot structure has been identified in patients with thrombotic disorders. Anticoagulant therapy offers clear benefits for thrombosis prevention and treatment by reducing blood clot formation and size; nevertheless, there are limited data on the effects of different anticoagulants, where clotting is initiated with different triggers, on clot structure.

OBJECTIVES

Our aim was to investigate the effects of vitamin K antagonists and factor Xa inhibitors on clot structure.

METHODS

Clots from pooled plasma spiked with rivaroxaban, apixaban, or enoxaparin, as well as plasma from patients on warfarin, were compared to plasma without anticoagulation. The kinetic profile of polymerizing clots was obtained by turbidity, fiber density was determined by confocal microscopy, clot pore size was investigated by permeation, and fiber size was analyzed using scanning electron microscopy. Clotting agonist was either tissue factor or thrombin.

RESULTS

Following clotting with tissue factor, all anticoagulated clots had a significantly increased lag time, with the exception of enoxaparin. Rivaroxaban additionally led to significantly less dense and more permeable clots, with thicker fibers. In contrast, turbidity analysis following initiation with thrombin showed few effects of anticoagulation, with only enoxaparin leading to a prolonged lag time. Enoxaparin clots made with thrombin were less dense and more permeable.

CONCLUSION

Our results show that anticoagulants modulate clot structure particularly when induced by tissue factor, most likely due to reduction of thrombin generation. We propose that the effects of different anticoagulants could be assessed with a global clot structure measurement such as permeation or turbidity, providing information on clot phenotype.

Therapeutic potential of coumarin bearing metal complexes: Where are we headed?

The successfully application of some metallodrugs such as salvarsan, silver sulfadiazine and cisplatin in modern medicine launched the biological investigation of organometallic and metal-organic complexes. The availability and tunability of various ligands including N-heterocycles, phosphines, N-heterocyclic carbenes present an extended research area to chemists. In recent years, the preparation of the metal complexes of bioactive organic compounds is a new strategy. Coumarin derivatives are one of the classes of compounds used for this purpose, and many complexes of coumarin derivatives were prepared for enhanced biological activity, especially anticancer and antimicrobial. In this paper, we discuss the current situation of this topic.

Factors Influencing Various Aspects of Patients' Knowledge of Oral Anticoagulation

OBJECTIVES

To identify and examine individual characteristics and socioeconomic factors that contribute to the knowledge of patients who receive warfarin anticoagulation.

METHODS

All patients treated using warfarin for anticoagulation were enrolled during a 6-month period at a university-affiliated cardiac clinic. All relevant demographic and clinical information were collected and the Anticoagulation Knowledge Assessment (AKA) questionnaire consisting of 29 questions was administered. After completion, the questionnaires were scored and the percent correct answers were analyzed for overall scores, as well as the following categories: drug/food interactions, pharmacological knowledge, recognition of complications, and patient compliance. Multiple linear regression analysis was used to identify the contributing factors to the knowledge level of the patients in each category.

RESULTS

One hundred fifty patients (79 men and 71 women) with a median age of 61.5 years completed the AKA questionnaire. The average overall score was 29.3%. Living alone (P = 0.008), higher levels of education (P = 0.001), and durations of ≥3 years of warfarin therapy (P = 0.018) positively impacted overall AKA scores.

CONCLUSIONS

Socioeconomic factors and level of general education remain the most important elements determining the patient awareness of therapeutic goals, possible drug/food interaction, recognition of adverse effects, and compliance of warfarin treatment.

Anticoagulant and Antithrombotic Properties of Three Structurally Correlated Sea Urchin Sulfated Glycans and Their Low-Molecular-Weight Derivatives

The anticoagulant and antithrombotic properties of three structurally correlated sea urchin-derived 3-linked sulfated α-glycans and their low molecular-weight derivatives were screened comparatively through various in vitro and in vivo methods. These methods include activated partial thromboplastin time, the inhibitory activity of antithrombin over thrombin and factor Xa, venous antithrombosis, the inhibition of platelet aggregation, the activation of factor XII, and bleeding. While the 2-sulfated fucan from Strongylocentrotus franciscanus was observed to be poorly active in most assays, the 4-sulfated fucan from Lytechinus variegatus, the 2-sulfated galactan from Echinometra lucunter and their derivatives showed multiple effects. All marine compounds showed no capacity to activate factor XII and similar low bleeding tendencies regardless of the dose concentrations used to achieve the highest antithrombotic effect observed. The 2-sulfated galactan showed the best combination of results. Our work improves the background about the structure-function relationship of the marine sulfated glycans in anticoagulation and antithrombosis. Besides confirming the negative effect of the 2-sulfated fucose and the positive effect of the 2-sulfated galactose on anticoagulation in vitro, our results also demonstrate the importance of this set of structural requirements on antithrombosis in vivo, and further support the involvement of high-molecular weight and 4-sulfated fucose in both activities.

Direct oral anticoagulants and venous thromboembolism

Venous thromboembolism (VTE), consisting of deep vein thrombosis and pulmonary embolism, is a major clinical concern associated with significant morbidity and mortality. The cornerstone of management of VTE is anticoagulation, and traditional anticoagulants include parenteral heparins and oral vitamin K antagonists. Recently, new oral anticoagulant drugs have been developed and licensed, including direct factor Xa inhibitors (e.g. rivaroxaban, apixaban and edoxaban) and thrombin inhibitors (e.g. dabigatran etexilate). This narrative review focusses on the characteristics of these direct anticoagulants and the main results of published clinical studies on their use in the prevention and treatment of VTE.

[Posttraumatic thromboembolic complications: Incidence, risk factors, pathophysiology and prevention]

Venous thromboembolism (VTE) remains a major challenge in critically ill patients. Subjects admitted in intensive care unit (ICU), in particular trauma patients, are at high-risk for both deep vein thrombosis (DVT) and pulmonary embolism (PE). The rate of symptomatic PE in injured patients has been reported previously ranging from 1 to 6%. The high incidence of posttraumatic venous thromboembolic events is well known. In fact, major trauma is a hypercoagulable state. Several factors placing the individual patient at a higher risk for the development of DVT and PE have been suggested: high ISS score, meningeal hemorrhage and spinal cord injuries have frequently been reported as a significant risk factor for VTEs after trauma. Posttraumatic pulmonary embolism traditionally occurs after a period of at least 5 days from trauma. The prevention can reduce the incidence and mortality associated with the pulmonary embolism if it is effective. There is no consensus is now available about the prevention of venous thromboembolism in trauma patients.

Thrombin-Responsive Transcutaneous Patch for Auto-Anticoagulant Regulation

A thrombin-responsive closed-loop patch is developed for prolonged heparin delivery in a feedback-controlled manner. This microneedle-based patch can sense activated thrombin and subsequently releases heparin to prevent coagulation in the blood flow. This "smart" heparin patch can be transcutaneously inserted into skin without drug leakage and can sustainably regulate blood coagulation in response to thrombin.

Coagulation factor XI vaccination: an alternative strategy to prevent thrombosis

Essentials Coagulation Factor (F) XI is a safe target for the development of antithrombotics. We designed an antigen comprising the human FXI catalytic domain and diphtheria toxin T domain. Antigen immunization reduced plasma FXI activity by 54% and prevented thrombosis in mice. FXI vaccination can serve as an effective strategy for thrombosis prevention.

SUMMARY

Background Coagulation factor XI serves as a signal amplifier in the intrinsic coagulation pathway. Blockade of FXI by mAbs or small-molecule inhibitors inhibits thrombosis without causing severe bleeding, which is an inherent risk of currently available antithrombotic agents. Objectives To design an FXI vaccine and assess its efficacy in inhibiting FXI activity and preventing thrombosis. Methods An FXI antigen was generated by fusing the catalytic domain of human FXI to the C-terminus of the transmembrane domain of diphtheria toxin. The anti-FXI antibody response, plasma FXI activity and antithrombotic efficacy in mice immunized with the FXI antigen were examined. Results The antigen elicited a significant antibody response against mouse FXI, and reduced the plasma FXI activity by 54.0% in mice. FXI vaccination markedly reduced the levels of coagulation and inflammation in a mouse model of inferior vena cava stenosis. Significant protective effects were also observed in mouse models of venous thrombosis and pulmonary embolism. Conclusions Our data demonstrate that FXI vaccination can serve as an effective strategy for thrombosis prevention.

Profiles of direct oral anticoagulants and clinical usage-dosage and dose regimen differences

The availability of direct oral anticoagulants (DOACs) has caused a paradigm shift in thrombosis management. DOAC profiles do not differ greatly, though they are quite different from that of warfarin, whereas their dosage and dose regimens are not consistent. The direct thrombin inhibitor dabigatran seems to obstruct tenase by inhibiting thrombin generated in the initial phase and feedback to the amplification phase of cell-based coagulation reactions. Factor Xa inhibitors (rivaroxaban, apixaban, edoxaban) mainly inhibit factor Xa activity of the prothrombinase complex in the propagation phase. The dose regimens of these inhibitors can be classified into once (rivaroxaban, edoxaban) and twice (dabigatran, apixaban) daily. On the other hand, their plasma elimination half-life times are similar, which can be explained by differences in the type of aimed anticoagulation, such as persistent (e.g., warfarin) and intermittent (e.g., low-molecular-weight heparin). Because of the differences among DOACs, an indicator is necessary to compare them. We investigated relative potency to compare dosage and intensity by calculation of conversion using a profile comprised of molecular weight, bioavailability, protein-binding rate, inhibitory constant, and dosage. We found that the relative potencies were different, with that of apixaban higher than edoxaban (60 mg) and nearly twice that of rivaroxaban. However, dabigatran could not be evaluated with this profile, likely due to its different mode of action. These results suggest that rivaroxaban and apixaban differ in regard to anticoagulation type, as the former shows persistent and the latter intermittent anticoagulation.

The evolution of anticoagulant therapy

Arterial and venous thromboembolism are leading causes of morbidity and mortality around the world. For almost 70 years, heparins (unfractionated heparin and low molecular weight heparins) and vitamin K antagonists have been the leading therapeutic medical options for the treatment and prevention of thromboembolic disorders. Nevertheless, the many limitations of these traditional anticoagulants have fuelled the search for novel agents over the past 15 years, and a new class of oral anticoagulants that specifically target activated factor X and thrombin has been developed and is now commercially available. In this narrative review, the evolution of anticoagulant therapy is summarised, with a focus on newer oral anticoagulants.

Facile chemoenzymatic synthesis of biotinylated heparosan hexasaccharide

A biotinylated heparosan hexasaccharide was synthesized using a one-pot multi-enzyme strategy, in situ activation and transfer of N-trifluoroacetylglucosamine (GlcNTFA) to a heparin backbone significantly improved the synthetic efficiency. The biotinylated hexasaccharide could serve as a flexible core to diversify its conversion into heparan sulfate isoforms with potential biological applications and therapeutics.

Novel oral anticoagulants: what dermatologists need to know

The development of novel oral anticoagulants provides clinicians and patients a welcome alternative to the challenges of warfarin therapy. Dermatologists must be aware of the potential impact of novel oral anticoagulants on their surgical and medical practice. This review provides a concise summary of the novel oral anticoagulants for dermatologists with particular emphasis on: (1) the pharmacokinetic properties of these drugs and how they differ from warfarin, (2) suggested management during cutaneous surgery, (3) adverse drug interactions with commonly prescribed medications in dermatology, and (4) potential use within dermatology for treatment of disorders of cutaneous thrombosis.

Self-titrating anticoagulant nanocomplexes that restore homeostatic regulation of the coagulation cascade

Antithrombotic therapy is a critical portion of the treatment regime for a number of life-threatening conditions, including cardiovascular disease, stroke, and cancer; yet, proper clinical management of anticoagulation remains a challenge because existing agents increase the propensity for bleeding in patients. Here, we describe the development of a bioresponsive peptide-polysaccharide nanocomplex that utilizes a negative feedback mechanism to self-titrate the release of anticoagulant in response to varying levels of coagulation activity. This nanoscale self-titrating activatable therapeutic, or nanoSTAT, consists of a cationic thrombin-cleavable peptide and heparin, an anionic polysaccharide and widely used clinical anticoagulant. Under nonthrombotic conditions, nanoSTATs circulate inactively, neither releasing anticoagulant nor significantly prolonging bleeding time. However, in response to life-threatening pulmonary embolism, nanoSTATs locally release their drug payload and prevent thrombosis. This autonomous negative feedback regulator may improve antithrombotic therapy by increasing the therapeutic window and decreasing the bleeding risk of anticoagulants.

Effects on bleeding complications of pharmacogenetic testing for initial dosing of vitamin K antagonists: a systematic review and meta-analysis

BACKGROUND

Although warfarin and other vitamin K antagonists (VKAs) are the most widely used oral anticoagulants for the prevention and treatment of thromboembolic events, a number of factors hamper their manageability, the most important being the inter-individual variability of the therapeutic dose requirement. Following the discovery of the influence of CYP2C9 and VKORC1 polymorphisms on VKA dose requirements, there has been interest in genotype-guided VKA dosing in order to reduce the risk of over-anticoagulation at the time of therapy initiation and hence the risk of bleeding, particularly prominent during the early days of treatment. To assess the impact on clinical outcomes of pharmacogenetic testing for initial VKA dosing, we have performed a systematic review and meta-analysis of the literature.

METHODS

MEDLINE, EMBASE and Cochrane databases were searched up to March 2014. Only randomized controlled trials comparing genotype-guided vs. clinically-guided warfarin dosing were included.

RESULTS

Nine trials including 2812 patients met the inclusion criteria and were pooled for meta-analytical evaluation. Risk of bias, assessed according to the Cochrane methodology, showed a low risk for the majority of domains analyzed in the included trials. A statistically significant reduction in the risk ratio (RR) for developing major bleeding events was observed in the pharmacogenetic-guided group compared with the control group (RR = 0.47; 95% CI, 0.23-0.96; P = 0.040).

CONCLUSIONS

The results of this meta-analysis show that genotype-guided initial VKA dosing is able to reduce serious bleeding events by approximately 50% compared with clinically-guided dosing approaches.

Anticoagulant therapy in pediatrics

Thromboembolic episodes are disorders encountered in both children and adults, but relatively more common in adults. However, the occurrence of venous thromboembolism and use of anticoagulants in pediatrics are increasing. Unfractionated Heparin (UH) is used as a treatment and prevention of thrombosis in adults and critically ill children. Heparin utilization in pediatric is limited by many factors and the most important ones are Heparin Induced Thrombocytopenia (HIT) and anaphylaxis. However, Low Molecular Weight Heparin (LMWH) appears to be an effective and safe alternative treatment. Hence, it is preferred over than UH due to favorable pharmacokinetic and side effect profile. Direct Thrombin Inhibitors (DTI) is a promising class over the other anticoagulants since it offers potential advantages. The aim of this review is to discuss the differences between adult and pediatric thromboembolism and to review the current anticoagulants in terms of pharmacological action, doses, drug reactions, pharmacokinetics, interactions, and parameters. This review also highlights the differences between old and new anticoagulant therapy in pediatrics.

[Dabigatran: transforming the management of oral anticoagulation]

The utility of oral anticoagulation with warfarin in thromboembolic disease has been demonstrated for several decades, although these drugs have significant problems in terms of adequate control, interactions and risk of bleeding. In the last decade, new anticoagulants have emerged. The first was dabigatran with a demonstrated anticoagulant effect approaching the ideal anticoagulant profile. The view that dabigatran transforms oral anticoagulation therapy has arisen from the RE-VOLUTION program, with more than 34000 patients analyzed. This program has confirmed the value of oral anticoagulation with dabigatran compared with other anticoagulants; this drug eliminates all the drawbacks of warfarin, benefitting both patients and the healthcare system. The growth of the aging population has increased the number of risk situations in which anticoagulation is used. There is now a drug that meets the criteria for the ideal anticoagulant, transforming the management of oral anticoagulation. The findings demonstrated with dabigatran in prior studies are progressively being transferred to clinical practice. Following the usual development of new drugs, and according to the latest Laurence Desmond stages, results in agreement with those of previous studies are expected, namely, indisputable improvements in oral anticoagulation for patients and the health system.

Patient preferences and willingness to pay for different options of anticoagulant therapy

New anticoagulant drugs alternative to vitamin K antagonists are currently under clinical evaluation. Patient's preferences should be considered in the development of new therapeutic strategies. Our study aim was to elicit patient preferences, and estimate their willingness to pay for the different treatment options. A Discrete Choice Experiment was administered to patients consecutively attending an anticoagulation clinic, either on stable oral anticoagulant therapy, or during their first visit at the time of starting therapy. Six treatment characteristics were analysed: route and number of medication administrations, frequency of monitoring, risk of some minor bleeding, the amount of attention required for drug/food interactions, requirement for dose adjustment, and out-of-pocket treatment cost. Relationships between patient's preferences and their characteristics were analysed. 255 patients participated (55 % men, with a mean age 64 years; 35.7 % on stable therapy). A statistically significant importance was attributed to all but two characteristics (the amount of attention required for interaction with other drugs/food and for dose adjustment.) Monthly patient willingness to pay was <euro> 79 for tablets versus injections; <euro> 41 for once-daily versus twice-daily tablets, <euro> 25 for drugs without risk of minor bleeding events and <euro> 20 for once-monthly versus twice-monthly monitoring. Patients on stable therapy considered more important the amount of attention required for drug/food interactions than did the starters. Younger or working patients considered the reduction of monitoring frequency more important than did the older or not working patients (retired, housewives). This study elicited preferences from patients on oral anticoagulant therapy with a simple and well established method, which allows to obtain information warranted for planning optimal healthcare.

New anticoagulants for treatment of venous thromboembolism

Venous thromboembolism (VTE) is a major cause of morbidity and mortality and anticoagulation is the cornerstone of treatment. Although effective, traditional anticoagulants (i.e., heparins and vitamin K antagonists) have significant limitations and there are several unmet needs. Therefore, new drugs have been developed, including direct factor Xa inhibitors (e.g., rivaroxaban, apixaban and edoxaban) and thrombin inhibitors (e.g., dabigatran etexilate). The characteristics of these agents and the main results of published clinical studies dealing with VTE treatment are critically summarized in this article.

Nucleic acid scavengers inhibit thrombosis without increasing bleeding

Development of effective, yet safe, antithrombotic agents has been challenging because such agents increase the propensity of patients to bleed. Recently, naturally occurring polyphosphates such as extracellular DNA, RNA, and inorganic polyphosphates have been shown to activate blood coagulation. In this report, we evaluate the anticoagulant and antithrombotic activity of nucleic acid-binding polymers in vitro and in vivo. Such polymers bind to DNA, RNA, and inorganic polyphosphate molecules with high affinity and inhibit RNA- and polyphosphate-induced clotting and the activation of the intrinsic pathway of coagulation in vitro. Moreover, [NH(2)(CH(2))(2)NH(2)](G = 3);dendri PAMAM(NH(2))(32) (PAMAM G-3) prevents thrombosis following carotid artery injury and pulmonary thromboembolism in mice without significantly increasing blood loss from surgically challenged animals. These studies indicate that nucleic acid-binding polymers are able to scavenge effectively prothrombotic nucleic acids and other polyphosphates in vivo and represent a new and potentially safer class of antithrombotic agents.

Current and future management of pediatric venous thromboembolism

Venous thromboembolism (VTE) is an increasingly common complication encountered in tertiary care pediatric settings. The purpose of this review is to summarize the epidemiology, current and emerging pharmacotherapeutic options, and management of this disease. Over 70% of VTE occur in children with chronic diseases. Although they are seen in children of all ages, adolescents are at greatest risk. Pediatric VTE is associated with an increased risk of in-hospital mortality; recurrent VTE and post-thrombotic syndrome are commonly seen in survivors. In recent years, anticoagulation with low molecular weight heparin has emerged as the mainstay of therapy, but compliance is limited by its onerous subcutaneous administration route. New anticoagulants either already approved for use in adults or in the pipeline offer the possibility of improved dose stability and oral routes of administration. Current recommended anticoagulation course durations are derived from very limited case series and cohort data, or extrapolations from adult literature. However, the pathophysiologic underpinnings of pediatric VTE are dissimilar from those seen in adults and are often variable within groups of pediatric patients. Clinical studies and trials in pediatric VTE are underway which will hopefully improve the quality of evidence from which therapeutic guidelines are derived.

New oral anticoagulants: will they replace warfarin?

Vitamin K antagonists, such as warfarin, are considered to be the treatment of choice to prevent thromboembolic events, but problems, such as the need for frequent dose adjustment and monitoring of coagulation status, as well as multiple drug and food interactions, make their use difficult for both physician and patient. Two new anticoagulants are now being considered as possible replacements of vitamin K antagonists. Dabigatran, an oral direct thrombin inhibitor has already been approved in the USA for prevention of stroke in patients with atrial fibrillation. Rivaroxaban, a factor Xa inhibitor, and dabigatran are licensed in Europe and Canada for short-term thromboprophylaxis after elective hip or knee replacement surgery. The advantages of these drugs are that they are safe and effective, require no monitoring, have a direct mode of action against only one clotting factor (thrombin or factor Xa), have limited drug interactions, and have rapid peak blood levels. Based on the fact that dabigatran has already been approved for use in the USA, it would appear that it has an advantage over rivaroxaban in becoming the replacement drug for vitamin K antagonists.

Synthesis and biochemical evaluation of triazole/tetrazole-containing sulfonamides against thrombin and related serine proteases

A small library of 25 triazole/tetrazole-based sulfonamides have been synthesized and further evaluated for their inhibitory activity against thrombin, trypsin, tryptase and chymase. In general, the triazole-based sulfonamides inhibited thrombin more efficiently than the tetrazole counterparts. Particularly, compound 26 showed strong thrombin inhibition (K(i)=880 nM) and significant selectivity against other human related serine proteases like trypsin (K(i)=729 μM). Thrombin binding affinity of the same compound was determined by ITC and demonstrated that the binding of this new triazole-based scaffold is enthalpically driven, making it a good candidate for further development.

Challenges of Older Patients’ Knowledge About Warfarin Therapy

Objective: To review the challenges of warfarin education for older patients (aged 65 years or older) in terms of knowledge, access to warfarin education, and education resources. Methods: A quasi-systematic review of the literature was performed via electronic database searches (eg, Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, International Pharmaceutical Abstracts, Meditext, and Google Scholar) from 1990 to May 2011. Results: The 62 articles reviewed found that improved patient knowledge results in better anticoagulation control. The review also found that between 50% and 80% of older patients have inadequate knowledge about the basic aspects of warfarin therapy (eg, action, benefits and risks, interactions with other drugs or foods, international normalized ratio management). Demographic factors, such as advancing age, lower family income, and limited health literacy, were found to inversely affect patients’ warfarin knowledge, and access to warfarin education and information resources were often suboptimal in different practice settings. Finally, a number of educational strategies and resources that could be readily incorporated to improve the effectiveness of current warfarin education programs were extracted from the review. Conclusion: This comprehensive review highlights that education about warfarin in older patients is currently suboptimal and may in part contribute to poor therapeutic outcomes. This review article also acknowledges the need to identify, target, and develop educational strategies and resources to further improve older patients’ knowledge about their warfarin therapy.