Review of the Pharmacology of the Emerging Possibilities of the Direct Oral Anticoagulants' Reversal

ROTEM Testing for Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) are increasingly used worldwide for the prevention of stroke in patients with atrial fibrillation and to prevent or treat venous thromboembolism. In situations such as serious bleeding, the need for urgent surgery/intervention or the management of a thromboembolic event, the laboratory measurement of DOACs levels or anticoagulant activity may be required. Rotational thromboelastometry (ROTEM) is a viscoelastic hemostatic assay (VHA) which has been used in emergencies (trauma and obstetrics), and surgical procedures (cardiac surgery and liver transplants), but experience with this assay in DOACs-treated patients is still limited. This article reviews the use of ROTEM in the setting of DOACs therapy, focusing on DOACs-associated bleeding and the use of this VHA for the management of reversal strategies for DOACs-associated anticoagulation.

Direct Oral Anticoagulants: Novel Approach for the Treatment of Thrombosis in Pediatric Patients?

Venous thromboembolism (VTE) is a rare, but life-threatening disease in those who have not reached their adulthood. This condition is usually treated with heparin or low molecular weight heparins which require parenteral administration and, in case of unfractionated heparin, also frequent laboratory monitoring and dose adjustment. Direct oral anticoagulants (DOACs)-direct thrombin inhibitor dabigatran, and direct oral factor Xa inhibitors rivaroxaban, apixaban, and edoxaban-are currently frequently used for the prevention and treatment of VTE in adult population. In fact, these agents offer several advantages compared to traditional agents, such as oral route of administration, short on-set and off-set of action, predictable pharmacologic profile with low risk of food and drug interactions, and no need for routine laboratory assessment of anticoagulant activity. However, clinical experience with these directly acting oral anticoagulants in pediatric population is very limited as these drugs had been tested and are used mostly in adult individuals. This article reviews the current data from pre- and post-marketing studies reporting the use of DOACs for the treatment of VTE in pediatric patients.

A Validated Chiral-RP-UPLC-MS/MS Method for the Enantiomeric Detection of Rivaroxaban In vitro

Background:

Rivaroxaban is the first oral, selective direct FXa inhibitor with rapid onset of action and its biological toxicity may be related to the enantiomer. </P><P> Objective: The aim of the current study was to develop and validate a precise, accurate, and specific direct Chiral-RP-UPLC-MS/MS method for the enantiomeric separation and detection of rivaroxaban and its enantiomer.

Methods:

The present study screened various conditions of chromatographic and mass spectra, including chromatographic column model, flow velocity, phase ratio, column temperature, and collision energy, parent/daughter ion pairs, etc. Try to match the chromatographic and mass spectrometric conditions.

Results:

Good Rs (Rs>2.5) was achieved on a Chiralpak IC column (4.6 × 250 mm, 5µm) using H2O:acetonitrile (10:90) as mobile phase at 25 oC column temperature. The rate of flow was set at 0.4 ml/min and enantiomers were detected by triple-quadruple tandem mass spectrometry using positive electrospray ionization (ESI) with MRM transitions of m/z 436.07>144.95. The cone voltage and collision energy were kept at 48 V and 28 eV, respectively. The limit of detection and quantification of (S)- rivaroxaban were 0.39 and 1.30 ng/ml, respectively. This method was validated and found to be selective, precise, accurate, linear and robust for the quantitative determination of chiral impurities. It is also a good application for the blood samples analysis in vitro.

Conclusion:

Chiral-RP-UPLC-MS/MS method has entirely detected (S)-rivaroxaban and its (R)- enantiomer in very low concentration and complex matrix directly, especially for blood samples.