New oral anticoagulants: clinical indications, monitoring and treatment of acute bleeding complications

Development and validation of a quantification method for direct oral anticoagulants from capillary blood using volumetric absorptive microsampling and online SPE-LC-MS

The number of prescriptions for new direct oral anticoagulants (DOACs) apixaban, edoxaban, rivaroxaban and dabigatran has increased exponentially in recent years, increasingly replacing the old gold standard, vitamin-K-antagonists. Due to their wide therapeutic range, therapeutic drug monitoring (TDM) is not required, although it has been proven that this could significantly reduce side effects. In order to develop a cost-efficient and simple method for the simultaneous detection of the DOACs and phenprocoumon, a new technology for sample preparation from capillary blood in the ambulant sector named VAMS® was integrated and an LC-MS detector with on-line solid phase extraction (SPE) applying a Turboflow HTLC CycloneTM 1.0x50 mm column was used. The mobile phase consisted of methanol with water (3/97 v/v) and 0.1 % ammonia solution with a flow rate of 2.5 mL/min. For the chromatographic separation, a Phenomenex LTD Kinetex 2.6 µm C18 100 Å, 100x3.0 mm column with a flow rate of 0.3 mL/min in gradient mode was utilized. The mobile phase consisted of acetonitrile, water and formic acid (A: 10:90:0.1 v/v and B: 95:05:0.1 v/v). The method was fully validated in the therapeutic range of the substances according to current guidelines. The LLOQ ranged from 3.5 µg/L for rivaroxaban to 88 µg/L for phenprocoumon and the intra-day and inter-day precision was less than 13 % and 12 %, while the accuracy was within a range of 85.7-113 % and 88.7-106 %, respectively. Samples could be stored in the Mitra® devices for at least seven days at room temperature except of dabigatran. Because the Mitras® were used, exactly 10 µL of blood could be drawn and no significant haematocrit effect was observed. A reliable, simple and cost-effective extraction and analysis LC-MS method could be developed and validated. This method is therefore applicable in ambulatory care.

Measurement of apixaban concentrations in different human biological fluids by UHPLC-MS/MS. Clinical pharmacokinetic application in a subject with chronic kidney disease and nonvalvular atrial fibrillation on haemodialysis

BACKGROUND

Apixaban's technical sheet does not recommend its use in clinical practice for patients with chronic kidney disease undergoing haemodialysis. However, recent studies indicate that apixaban could be a safe oral anticoagulant in these kinds of patients who do not present valvular atrial fibrillation. We developed and validated ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) procedures for measuring apixaban concentrations in plasma, dialysate liquid, and urine.

MATERIAL AND METHODS

Simple protein precipitation was implemented to prepare samples. Chromatographic separations were achieved on an Acquity®-UPLC®-BEHTM (2.1x100 mm id, 1.7 µm) reverse-phase C18 column using a water/acetonitrile non-linear gradient containing 0.1 % formic acid at a 0.4 mL/min flow rate. Apixaban and its internal standard (apixaban-d3) were detected by electrospray ionisation mass spectrometry in positive and multiple reaction monitoring modes, using transitions of 460.3 → 199.0/443.2 and 463.3 → 202.0, respectively.

RESULTS

No significant interferences and carry-overs were observed. Precisions, absolute relative biases, normalised-matrix factors, and normalised recoveries were ≤ 12.2%, ≤8.0%, 94.3-105.1%, and 93.9-105.4%, respectively. Linearity was observed between 5 and 500 μg/L for plasma/dialysate liquid and 5-1000 μg/L for urine.

CONCLUSIONS

The validated UHPLC-MS/MS procedures could help support a pharmacokinetic study in non-valvular atrial fibrillation subjects with chronic kidney disease undergoing haemodialysis and apixaban-based anticoagulant therapy.

Rapid Assay for the Therapeutic Drug Monitoring of Edoxaban

Edoxaban is a direct oral anticoagulant (DOAC) that has been recently indicated for the treatment of pulmonary embolism (PE) in SARS-CoV-2 infections. Due to its pharmacokinetic variability and a narrow therapeutic index, the safe administration of the drug requires its therapeutic drug monitoring (TDM) in patients receiving the treatment. In this work, we present a label-free method for the TDM of edoxaban by surface enhanced Raman spectroscopy (SERS). The new method utilises the thiol chemistry of the drug to chemisorb its molecules onto a highly sensitive SERS substrate. This leads to the formation of efficient hotspots and a strong signal enhancement of the drug Raman bands, thus negating the need for a Raman reporter for its SERS quantification. The standard samples were run with a concentration range of 1.4 × 10⁻⁴ M to 10⁻¹² M using a mobile phase comprising of methanol/acetonitrile (85:15 v/v) at 291 nm followed by the good linearity of R² = 0.997. The lowest limit of quantification (LOQ) by the SERS method was experimentally determined to be 10⁻¹² M, whereas LOQ for HPLC-UV was 4.5 × 10⁻⁷ M, respectively. The new method was used directly and in a simple HPLC-SERS assembly to detect the drug in aqueous solutions and in spiked human blood plasma down to 1 pM. Therefore, the SERS method has strong potential for the rapid screening of the drug at pathology labs and points of care.

Quantification of Apixaban, Dabigatran, Edoxaban, and Rivaroxaban in Human Serum by UHPLC-MS/MS-Method Development, Validation, and Application

BACKGROUND

Direct oral anticoagulants (DOACs) are prescribed for anticoagulation in patients with atrial fibrillation and venous thromboembolic disease. Fixed doses are recommended, but measuring their serum drug concentrations as a basis for dose adjustments may be useful in some clinical settings.

METHODS

An ultra-high-performance liquid chromatography-tandem mass spectrometry method for the analysis of the DOACs apixaban, dabigatran, edoxaban, and rivaroxaban in human serum was developed and validated. A 100-µL serum sample was handled using a pipetting robot. Protein precipitation was performed with 375 µL of 1% formic acid in acetonitrile (vol/vol), and phospholipid removal was performed using a Waters Ostro 96-well plate. The injection volume was 1 µL, and run time was 3.0 minutes.

RESULTS

The calibration range was 5-800 nmol/L. The between-day precision relative SDs were in the range of 3.3%-10%. Recoveries ranged from 85% to 105%, and matrix effects from 88% to 102%, when corrected with internal standard. Edoxaban was, in contrast to the other DOACs, unstable when stored for more than 6 hours at 30°C. The suitability of the method was demonstrated by analyzing routine samples from 345 patients undergoing anticoagulation treatment.

CONCLUSIONS

The developed method fulfilled the set validation criteria, and its suitability was demonstrated in a routine setting. The instability of edoxaban may complicate the transport of routine samples to the laboratory.

Reducing risk of spinal haematoma from spinal and epidural pain procedures

Background and aims:

Central neuraxial blocks (CNB: epidural, spinal and their combinations) and other spinal pain procedures can cause serious harm to the spinal cord in patients on antihaemostatic drugs or who have other risk-factors for bleeding in the spinal canal. The purpose of this narrative review is to provide a practise advisory on how to reduce risk of spinal cord injury from spinal haematoma (SH) during CNBs and other spinal pain procedures. Scandinavian guidelines from 2010 are part of the background for this practise advisory.

Methods:

We searched recent guidelines, PubMed (MEDLINE), SCOPUS and EMBASE for new and relevant randomised controlled trials (RCT), case-reports and original articles concerning benefits of neuraxial blocks, risks of SH due to anti-haemostatic drugs, patient-related risk factors, especially renal impairment with delayed excretion of antihaemostatic drugs, and specific risk factors related to the neuraxial pain procedures.

Results and recommendations:

Epidural and spinal analgesic techniques, as well as their combination provide superior analgesia and reduce the risk of postoperative and obstetric morbidity and mortality. Spinal pain procedure can be highly effective for cancer patients, less so for chronic non-cancer patients. We did not identify any RCT with SH as outcome. We evaluated risks and recommend precautions for SH when patients are treated with antiplatelet, anticoagulant, or fibrinolytic drugs, when patients’ comorbidities may increase risks, and when procedure-specific risk factors are present. Inserting and withdrawing epidural catheters appear to have similar risks for initiating a SH. Invasive neuraxial pain procedures, e.g. spinal cord stimulation, have higher risks of bleeding than traditional neuraxial blocks. We recommend robust monitoring routines and treatment protocol to ensure early diagnosis and effective treatment of SH should this rare but potentially serious complication occur.

Conclusions:

When neuraxial analgesia is considered for a patient on anti-haemostatic medication, with patient-related, or procedure-related risk factors, the balance of benefits against risks of bleeding is decisive; when CNB are offered exclusively to patients who will have a reduction of postoperative morbidity and mortality, then a higher risk of bleeding may be accepted. Robust routines should ensure appropriate discontinuation of anti-haemostatic drugs and early detection and treatment of SH.

Implications:

There is an on-going development of drugs for prevention of thromboembolic events following surgery and childbirth. The present practise advisory provides up-to-date knowledge and experts’ experiences so that patients who will greatly benefit from neuraxial pain procedures and have increased risk of bleeding can safely benefit from these procedures. There are always individual factors for the clinician to evaluate and consider. Increasingly it is necessary for the anaesthesia and analgesia provider to collaborate with specialists in haemostasis. Surgeons and obstetricians must be equally well prepared to collaborate for the best outcome for their patients suffering from acute or chronic pain. Optimal pain management is a prerequisite for enhanced recovery after surgery, but there is a multitude of additional concerns, such as early mobilisation, early oral feeding and ileus prevention that surgeons and anaesthesia providers need to optimise for the best outcome and least risk of complications.

Anesthesia for interventional pulmonology procedures: a review of advanced diagnostic and therapeutic bronchoscopy

PURPOSE

Interventional pulmonology is a growing subspecialty of pulmonary medicine with flexible and rigid bronchoscopies increasingly used by interventional pulmonologists for advanced diagnostic and therapeutic purposes. This review discusses different technical aspects of anesthesia for interventional pulmonary procedures with an emphasis placed on pharmacologic combinations, airway management, ventilation techniques, and common complications.

SOURCE

Relevant medical literature was identified by searching the PubMed and Google Scholar databases for publications on different anesthesia topics applicable to interventional pulmonary procedures. Cited literature included case reports, original research articles, review articles, meta-analyses, guidelines, and official society statements.

PRINCIPAL FINDINGS

Interventional pulmonology is a rapidly growing area of medicine. Anesthesiologists need to be familiar with different considerations required for every procedure, particularly as airway access is a shared responsibility with pulmonologists. Depending on the individual case characteristics, a different selection of airway method, ventilation mode, and pharmacologic combination may be required. Most commonly, airways are managed with supraglottic devices or endotracheal tubes. Nevertheless, patients with central airway obstruction or tracheal stenosis may require rigid bronchoscopy and jet ventilation. Although anesthetic approaches may vary depending on factors such as the length, complexity, and acuity of the procedure, the majority of patients are anesthetized using a total intravenous anesthetic technique.

CONCLUSIONS

It is fundamental for the anesthesia provider to be updated on interventional pulmonology procedures in this rapidly growing area of medicine.

Oral anticoagulants for primary prevention, treatment and secondary prevention of venous thromboembolic disease, and for prevention of stroke in atrial fibrillation: systematic review, network meta-analysis and cost-effectiveness analysis

BACKGROUND

Warfarin is effective for stroke prevention in atrial fibrillation (AF), but anticoagulation is underused in clinical care. The risk of venous thromboembolic disease during hospitalisation can be reduced by low-molecular-weight heparin (LMWH): warfarin is the most frequently prescribed anticoagulant for treatment and secondary prevention of venous thromboembolism (VTE). Warfarin-related bleeding is a major reason for hospitalisation for adverse drug effects. Warfarin is cheap but therapeutic monitoring increases treatment costs. Novel oral anticoagulants (NOACs) have more rapid onset and offset of action than warfarin, and more predictable dosing requirements.

OBJECTIVE

To determine the best oral anticoagulant/s for prevention of stroke in AF and for primary prevention, treatment and secondary prevention of VTE.

DESIGN

Four systematic reviews, network meta-analyses (NMAs) and cost-effectiveness analyses (CEAs) of randomised controlled trials.

SETTING

Hospital (VTE primary prevention and acute treatment) and primary care/anticoagulation clinics (AF and VTE secondary prevention).

PARTICIPANTS

Patients eligible for anticoagulation with warfarin (stroke prevention in AF, acute treatment or secondary prevention of VTE) or LMWH (primary prevention of VTE).

INTERVENTIONS

NOACs, warfarin and LMWH, together with other interventions (antiplatelet therapy, placebo) evaluated in the evidence network.

MAIN OUTCOME MEASURES

Efficacy Stroke, symptomatic VTE, symptomatic deep-vein thrombosis and symptomatic pulmonary embolism. Safety Major bleeding, clinically relevant bleeding and intracranial haemorrhage. We also considered myocardial infarction and all-cause mortality and evaluated cost-effectiveness.

DATA SOURCES

MEDLINE and PREMEDLINE In-Process & Other Non-Indexed Citations, EMBASE and The Cochrane Library, reference lists of published NMAs and trial registries. We searched MEDLINE and PREMEDLINE In-Process & Other Non-Indexed Citations, EMBASE and The Cochrane Library. The stroke prevention in AF review search was run on the 12 March 2014 and updated on 15 September 2014, and covered the period 2010 to September 2014. The search for the three reviews in VTE was run on the 19 March 2014, updated on 15 September 2014, and covered the period 2008 to September 2014.

REVIEW METHODS

Two reviewers screened search results, extracted and checked data, and assessed risk of bias. For each outcome we conducted standard meta-analysis and NMA. We evaluated cost-effectiveness using discrete-time Markov models.

RESULTS

Apixaban (Eliquis^®, Bristol-Myers Squibb, USA; Pfizer, USA) [5 mg bd (twice daily)] was ranked as among the best interventions for stroke prevention in AF, and had the highest expected net benefit. Edoxaban (Lixiana^®, Daiichi Sankyo, Japan) [60 mg od (once daily)] was ranked second for major bleeding and all-cause mortality. Neither the clinical effectiveness analysis nor the CEA provided strong evidence that NOACs should replace postoperative LMWH in primary prevention of VTE. For acute treatment and secondary prevention of VTE, we found little evidence that NOACs offer an efficacy advantage over warfarin, but the risk of bleeding complications was lower for some NOACs than for warfarin. For a willingness-to-pay threshold of > £5000, apixaban (5 mg bd) had the highest expected net benefit for acute treatment of VTE. Aspirin or no pharmacotherapy were likely to be the most cost-effective interventions for secondary prevention of VTE: our results suggest that it is not cost-effective to prescribe NOACs or warfarin for this indication.

CONCLUSIONS

NOACs have advantages over warfarin in patients with AF, but we found no strong evidence that they should replace warfarin or LMWH in primary prevention, treatment or secondary prevention of VTE.

LIMITATIONS

These relate mainly to shortfalls in the primary data: in particular, there were no head-to-head comparisons between different NOAC drugs.

FUTURE WORK

Calculating the expected value of sample information to clarify whether or not it would be justifiable to fund one or more head-to-head trials.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005324, CRD42013005331 and CRD42013005330.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Reversal of Dabigatran Using Idarucizumab in a Septic Patient with Impaired Kidney Function in Real-Life Practice

Background. Immediate reversal of anticoagulation is essential when facing severe bleeding or emergency surgery. Although idarucizumab is approved for the reversal of dabigatran in many countries, clinical experiences are lacking, particularly in special patient-populations such as sepsis and impaired renal function. Case Presentation. We present the case of a 67-year-old male septic patient with a multilocular facial abscess and chronic kidney disease (GFR 36.5 mL/min). Thrombin time (TT) and activated partial thromboplastin time (aPTT) 15 hours after the last intake of 150 mg dabigatran were both prolonged (>120 sec, resp., 61 sec), as well as unbound dabigatran concentration (119.05 ng/mL). Before immediate emergency surgery dabigatran was antagonised using idarucizumab 2 × 2.5 g. Dabigatran concentration was not detectable 10 min after idarucizumab administration (<30 ng/mL). TT and aPTT time were normalised (16.2 sec, resp., 30.2 sec). Sepsis was controlled after surgery and kidney function remained stable. In the absence of postoperative bleeding, dabigatran was restarted 36 hours after admission. Conclusion. Idarucizumab successfully reversed the effect of dabigatran in real-life practice in a patient with sepsis and renal impairment and allowed emergency surgery with normal haemostasis. Efficacy and safety in real-life practice will nevertheless require prospective registries monitoring.

Tooth extraction in patients taking nonvitamin K antagonist oral anticoagulants

Background/purpose

The nonvitamin K antagonist oral anticoagulants direct-thrombin inhibitor dabigatran and the Xa inhibitors rivaroxaban and apixaban are now being used clinically. The course of the patients on these anticoagulants who underwent tooth extraction was assessed.

Materials and methods

The medical charts of these patients were investigated. Tooth extraction was performed while maintaining conventional anticoagulant therapy.

Results

Twenty-three teeth were extracted in 19 patients, including two surgical extractions. Among the 19 patients, nine patients ingested rivaroxaban, six apixaban, and four dabigatran. One patient on rivaroxaban showed persistent postoperative bleeding following two surgical extractions. Mild oozing was observed in five patients (two on rivaroxaban and three on apixaban). There was no bleeding episode in the patients on dabigatran.

Conclusion

The patients on rivaroxaban with a prolonged prothrombin time value have a higher risk of bleeding, especially undergoing surgical extraction. Apixaban correlates to neither activated partial thromboplastin time nor prothrombin time values and the countermeasures should be employed based on the clinical findings.

Treatment options for venous thromboembolism: lessons learnt from clinical trials

Venous thromboembolism (VTE), comprising deep vein thrombosis and pulmonary embolism, is a common condition associated with a significant clinical and economic burden. Anticoagulant therapy is the mainstay of treatment for VTE, having been shown to reduce the risk of death in patients with pulmonary embolism, and recurrence or extension of thrombi in patients with deep vein thrombosis during the initial treatment period. Long-term anticoagulation is indicated in some individuals with VTE, depending on individual risk of VTE recurrence and anticoagulant-related bleeding. Management of VTE in clinical practice is often complex because patients' characteristics and treatment needs may differ considerably from those encountered in clinical trials. Current guidelines recommend the use of either low molecular weight heparins or fondaparinux overlapping with and followed by a vitamin K antagonist for the initial treatment of VTE, with the vitamin K antagonist continued when long-term anticoagulation is required. These traditional anticoagulants have practical limitations that have led to the development of direct oral anticoagulants that directly target either Factor Xa or thrombin and are administered at a fixed dose without the need for routine coagulation monitoring. This review discusses practical considerations for hospital physicians and haematologists in the management of VTE treatment, including the potential for the direct oral anticoagulants to simplify treatment.