Stroke prevention in atrial fibrillation: understanding the new oral anticoagulants dabigatran, rivaroxaban, and apixaban

Microdosing Cocktail Assay Development for Drug-Drug Interaction Studies

Methodology for analysis of a microdosing drug cocktail designed to evaluate the contribution of drug transporters and drug metabolizing enzymes to disposition was developed using liquid chromatography-mass spectrometry-based detection. Fast and sensitive methods were developed and qualified for the quantification of statins (pitavastatin, pitavastain lactone, rosuvastatin, atorvastatin, 2-hydroxy, and 4-hydroxy atorvastatin), midazolam, and dabigatran in human plasma. Chromatographic separation was accomplished using reversed-phase liquid chromatography or hydrophilic interaction liquid chromatography with gradient elution and detection by tandem mass spectrometry in the positive ionization mode using electrospray ionization. The lower limit of quantitation (LLOQ) for the statins assay was 1 pg/mL for the 6 analytes with a linear range from 1 to 1000 pg/mL processing 250 μL plasma sample. The midazolam assay LLOQ was 0.5 pg/mL with a linear range of 0.5 to 1000 pg/mL. For the dabigatran assay, the LLOQ was 10 pg/mL with a linear range of 10 to 5000 pg/mL processing 100 μL plasma sample. The intraday and interday precision and accuracy of the assays were within acceptable ranges, and the assays were successfully applied to support a study where a microdose cocktail was dosed to healthy human subjects for simultaneous assessment of clinical drug-drug interactions mediated by major drug transporters and CYP3A.

New oral anticoagulants: appropriateness of prescribing in real-world setting

BACKGROUND

The new oral anticoagulants (NOAC) have been extensively studied in the clinical trial setting; however, concerns remain about the safety of prescribing in the elderly and patients with renal impairment.

AIM

The aim of this study was to assess the appropriateness of NOAC prescribing in a real-world setting in terms of patient selection and to compare patient demographics to those included in pivotal clinical trials.

METHODS

One hundred and seventy-six patients from three tertiary university teaching hospitals were identified over 3 months in 2014.

RESULTS

Median age of the cohort was 74 years (interquartile range: 61-81 years), with a range of 23-96 years. Overall, 34% of the study population were prescribed a NOAC inappropriately. Of these, treatment was contraindicated in 40%, predominantly due to severe renal impairment, 22% were prescribed an excessively high dose, while 38% were under dosed. Although community-initiated patients had poorer renal function (glomerular filtration rate 91.7 ± 55.7 vs 69.3 ± 38.9, P = 0.024), appropriateness of prescription was no different compared to hospital-initiated patients (78% during admission cf. 61% prior, P = 0.061). Appropriate prescribing was better in patients with venous thromboembolism compared to AF (85% appropriate cf. 60%, P = 0.021).

CONCLUSION

Our findings imply that there remains considerable uncertainty about appropriate prescribing and dosing of NOAC, particularly in patients with impaired renal function. We recommend judicious prescribing and regular monitoring of renal function in patients at high risk of complications from NOAC therapy.

Real life anticoagulation treatment of patients with atrial fibrillation in Germany: extent and causes of anticoagulant under-use

Oral anticoagulation (OAC) with either new oral anticoagulants (NOACs) or Vitamin-K antagonists (VKAs) is recommended by guidelines for patients with atrial fibrillation (AF) and a moderate to high risk of stroke. Based on a claims-based data set the aim of this study was to quantify the stroke-risk dependent OAC utilization profile of German AF patients and possible causes of OAC under-use. Our claims-based data set was derived from two German statutory health insurance funds for the years 2007-2010. All prevalent AF-patients in the period 2007-2009 were included. The OAC-need in 2010 was assumed whenever a CHADS2- or CHA2DS2-VASC-score was >1 and no factor that disfavored OAC use existed. Causes of OAC under-use were analyzed using multivariate logistic regression. 108,632 AF-prevalent patients met the inclusion criteria. Average age was 75.43 years, average CHA2DS2-VASc-score was 4.38. OAC should have been recommended for 56.1/62.9 % of the patients (regarding factors disfavouring VKA/NOAC use). For 38.88/39.20 % of the patient-days in 2010 we could not observe any coverage by anticoagulants. Dementia of patients (OR 2.656) and general prescription patterns of the treating physician (OR 1.633) were the most important factors increasing the risk of OAC under-use. Patients who had consulted a cardiologist had a lower risk of being under-treated with OAC (OR 0.459). OAC under-use still seems to be one of the major challenges in the real-life treatment of AF patients. Our study confirms that both patient/disease characteristics and treatment environment/general prescribing behaviour of physicians may explain the OAC under-use in AF patients.

General Practitioners' vitamin K antagonist monitoring is associated with better blood pressure control in patients with hypertension--a cross-sectional database study

Background

Patients requiring anticoagulation suffer from comorbidities such as hypertension. On the occasion of INR monitoring, general practitioners (GPs) have the opportunity to control for blood pressure (BP). We aimed to evaluate the impact of Vitamin-K Antagonist (VKA) monitoring by GPs on BP control in patients with hypertension.

Methods

We cross-sectionally analyzed the database of the Swiss Family Medicine ICPC Research using Electronic Medical Records (FIRE) of 60 general practices in a primary care setting in Switzerland. This database includes 113,335 patients who visited their GP between 2009 and 2013. We identified patients with hypertension based on antihypertensive medication prescribed for ≥6 months. We compared patients with VKA for ≥3 months and patients without such treatment regarding BP control. We adjusted for age, sex, observation period, number of consultations and comorbidity.

Results

We identified 4,412 patients with hypertension and blood pressure recordings in the FIRE database. Among these, 569 (12.9 %) were on Phenprocoumon (VKA) and 3,843 (87.1 %) had no anticoagulation. Mean systolic and diastolic BP was significantly lower in the VKA group (130.6 ± 14.9 vs 139.8 ± 15.8 and 76.6 ± 7.9 vs 81.3 ± 9.3 mm Hg) (p < 0.001 for both). The difference remained after adjusting for possible confounders. Systolic and diastolic BP were significantly lower in the VKA group, reaching a mean difference of −8.4 mm Hg (95 % CI −9.8 to −7.0 mm Hg) and −1.5 mm Hg (95 % CI −2.3 to −0.7 mm Hg), respectively (p < 0.001 for both).

Conclusions

In a large sample of hypertensive patients in Switzerland, VKA treatment was independently associated with better systolic and diastolic BP control. The observed effect could be due to better compliance with antihypertensive medication in patients treated with VKA. Therefore, we conclude to be aware of this possible benefit especially in patients with lower expected compliance and with multimorbidity.

Bleeding and clotting in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a relatively common inherited vascular disorder that was first described in 1864, and is notable for epistaxis, telangiectasia, and arterial venous malformations. While genetic tests are available, the diagnosis remains clinical, and is based on the Curacao criteria. Patients with HHT are at increased risk for both bleeding and clotting events. Because of these competing complications, hematologists are often faced with difficult clinical decisions. While the majority of management decisions revolve around bleeding complications, it is not infrequent for these patients to require anticoagulation for thrombosis. Any anticoagulation recommendations must take into account the bleeding risks associated with HHT. Recent reviews have found that HHT patients can be safely anticoagulated, with the most frequent complication being worsened epistaxis. Large clinical trials have shown that factor IIa and Xa inhibitors have less intracranial bleeding than warfarin, and basic coagulation research has provided a possible mechanism. This article describes the anticoagulation dilemma posed when a 62-year-old female patient with a history of bleeding events associated with HHT was diagnosed with a pulmonary embolism. The subsequent discussion focuses on the approach to anticoagulation in the HHT patient, and addresses the role of the new oral anticoagulants.

Sex differences in treatment quality of self-managed oral anticoagulant therapy: 6,900 patient-years of follow-up

Background

Patient-self-management (PSM) of oral anticoagulant therapy with vitamin K antagonists has demonstrated efficacy in randomized, controlled trials. However, the effectiveness and efficacy of PSM in clinical practice and whether outcomes are different for females and males has been sparsely investigated.The objective is to evaluate the sex-dependent effectiveness of PSM of oral anticoagulant therapy in everyday clinical practice.

Methods

All patients performing PSM affiliated to Aarhus University Hospital and Aalborg University Hospital, Denmark in the period 1996–2012 were included in a case-series study. The effectiveness was estimated using the following parameters: stroke, systemic embolism, major bleeding, intracranial bleeding, gastrointestinal bleeding, death and time spent in the therapeutic international normalized ratio (INR) target range. Prospectively registered patient data were obtained from two databases in the two hospitals. Cross-linkage between the databases and national registries provided detailed information on the incidence of death, bleeding and thromboembolism on an individual level.

Results

A total of 2068 patients were included, representing 6,900 patient-years in total. Males achieved a significantly better therapeutic INR control than females; females spent 71.1% of the time within therapeutic INR target range, whereas males spent 76.4% (p<0.0001). Importantly, death, bleeding and thromboembolism were not significantly different between females and males.

Conclusions

Among patients treated with self-managed oral anticoagulant therapy, males achieve a higher effectiveness than females in terms of time spent in therapeutic INR range, but the incidence of major complications is low and similar in both sexes.

Antithrombotic alternatives for stroke prevention in atrial fibrillation: critical differences and remaining questions

Three therapeutic alternatives for prevention of stroke in patients with atrial fibrillation are available in dabigatran (an oral direct thrombin inhibitor), rivaroxaban, and apixaban (both oral blood coagulation factor Xa inhibitors). Compared with warfarin, these new agents have a more predictable pharmacodynamic response and fewer major clinically relevant drug–drug interactions. These agents also have few, if any, food–drug interactions, and infrequent or no need for routine laboratory monitoring. These agents also bring new disadvantages, particularly lack of clearly defined reversal strategies, inability to effectively monitor patient response, and higher cost. Selection of the most appropriate oral antithrombotic agent for a given patient is dependent on clinician knowledge of the similarities and critical differences between the available antithrombotic medications.