Anticoagulation for non-valvular atrial aibrillation - towards a new beginning with ximelagatran

Rivaroxaban for treatment of intraventricular thrombus in Chagas disease

Chagas disease leads to congestive heart failure, apical aneurysm, and may cause stroke or systemic embolism for intraventricular thrombus. We present a case of a 61-year-old man admitted for stroke 5 months after a renal embolism. An intraventricular thrombus was observed, probably the source of the cerebral and renal embolisms. The patient refused warfarin and rivaroxaban was used instead. After 40 days of treatment the thrombus had dissolved, after 20 months of regular use of rivaroxaban no more embolic events were observed. The use of rivaroxaban was effective in preventing embolic events in Chagas disease and intraventricular thrombus. <Learning objective: Warfarin is recommended for stroke prevention in patients with Chagas disease and left ventricular dysfunction or apical aneurysm, even in the absence of thrombus. None of the new oral anticoagulants is recommended in this context. Rivaroxaban was safe and effective in preventing embolic events in a patient with Chagas disease and a ventricular thrombus.>.

Measuring quality of oral anticoagulation care: extending quality measurement to a new field

BACKGROUND

Oral anticoagulation with warfarin is an increasingly common medical intervention. Despite its efficacy, warfarin is difficult to manage, contributing to potential for patient harm. Efforts to measure the quality of oral anticoagulation care have focused disproportionately on the identification of ideal candidates for warfarin therapy, with comparatively little effort in measuring the quality of oral anticoagulation care once therapy has begun. To address this gap in the literature, a MEDLINE search was conducted for all papers relevant to possible quality measures in oral anticoagulation care, including measures of structure, process, and outcomes of care.

LIMITATIONS, CONCERNS, AND CHALLENGES OF QUALITY MEASUREMENT IN ORAL ANTICOAGULATION

Because they do not have intrinsic significance, measures of structure and process should be strongly related to outcomes that matter to merit our interest. Consensus guidelines may provide useful guidance to practicing clinicians but may not represent valid process measures. Outcome measures must be studied with databases that provide sufficient statistical power to reliably demonstrate real differences between providers or sites of care.

CONCLUSION

Oral anticoagulation care, a common and serious condition, is in need of a program of quality measurement. This article suggests a research agenda to begin such a program. Previous research has established the evidence for anticoagulant therapy across a broad spectrum of indications and has helped to achieve consensus on the optimal target intensity for various indications. The next task will be to use this body of evidence to develop valid measures of the structure, process, and outcomes of oral anticoagulation care. Quality indicators provide a framework for quality improvement, two goals of which are to maximize the effectiveness of therapy and to minimize harm.

INFLUENCE OF ERYTHROMYCIN ON THE PHARMACOKINETICS OF XIMELAGATRAN MAY INVOLVE INHIBITION OF P-GLYCOPROTEIN-MEDIATED EXCRETION

A pharmacokinetic interaction between erythromycin and ximelagatran, an oral direct thrombin inhibitor, was demonstrated in this study in healthy volunteers. To investigate possible interaction mechanisms, the effects of erythromycin on active transport mediated by P-glycoprotein (P-gp) in vitro in Caco-2 and P-gp-over-expressing Madin-Darby canine kidney-human multidrug resistance-1 cell preparations and on biliary excretion of melagatran in rats were studied. In healthy volunteers (seven males and nine females; mean age 24 years) receiving a single dose of ximelagatran 36 mg on day 1, erythromycin 500 mg t.i.d. on days 2 to 5, and a single dose of ximelagatran 36 mg plus erythromycin 500 mg on day 6, the least-squares mean estimates (90% confidence intervals) for the ratio of ximelagatran with erythromycin to ximelagatran given alone were 1.82 (1.64-2.01) for the area under the concentration-time curve and 1.74 (1.52-2.00) for the maximum plasma concentration of melagatran, the active form of ximelagatran. Neither the slope nor the intercept of the melagatran plasma concentration-effect relationship for activated partial thromboplastin time statistically significantly differed as a function of whether or not erythromycin was administered with ximelagatran. Ximelagatran was well tolerated regardless of whether it was administered with erythromycin. Erythromycin inhibited P-gp-mediated transport of both ximelagatran and melagatran in vitro and decreased the biliary excretion of melagatran in the rat. These results indicate that the mechanism of the pharmacokinetic interaction between oral ximelagatran and erythromycin may involve inhibition of transport proteins, possibly P-gp, resulting in decreased melagatran biliary excretion and increased bioavailability of melagatran.

Anaesthesia and new antithrombotic drugs

PURPOSE OF REVIEW

New anticoagulant drugs are introduced by the pharmaceutical industry on a regular basis. Anaesthesiologists are not always very familiar with these drugs although their use may augment perioperative bleeding and increase the likelihood of a compressing spinal haematoma when combined with epidural or spinal anaesthetic techniques. This review discusses the latest of these new anticoagulants and their consequences for anaesthesiological practice.

RECENT FINDINGS

Durning the last few years, selective factor Xa inhibitors, glycoprotein IIb/IIIa receptor antagonists and direct thrombin inhibitors have been introduced into clinical practice. These drugs are typically more reliable and efficacious, have a lower incidence of side effects, are easier to use and will not need routine monitoring of their anticoagulant effects. In addition, their superior efficacy often implies a more profound anticoagulant action while reversing agents are mostly lacking and clinical experience is limited.

SUMMARY

There is currently not enough information available to make any firm statements about the safety of combining regional anaesthesia and the new anticoagulant agents. Until such information becomes available, knowledge of the pharmacological profile of these drugs in terms of elimination half-life, the potential for thrombocytopenia and the availability of antagonizing drugs will help us to decide whether or not a major regional anaesthetic technique will be feasible in the individual patient treated with these new compounds.