Direct oral anticoagulants (DOACs) are often used if oral anticoagulation is required, such as to prevent thromboembolism for patients with nonvalvular atrial fibrillation or for treatment and prevention of venous thromboembolism. One advantage of DOACs is their predictable response and limited need for routine laboratory monitoring. However, drug-drug interactions with these agents are common and may increase the risk of bleeding or thrombosis. Important DOAC interactions are often due to medications that affect increase bleeding propensity or cytochrome P450 (CYP450) enzymes or transport proteins. Clinicians require practical considerations for managing common drug interactions involving DOACs.
This course is designed for physicians, physician assistants, and nurses involved in the care of patients who require anticoagulation therapy.
The purpose of this course is to provide prescribers and other healthcare professionals with the knowledge and skills necessary to identify and act to avoid or address drug-drug interactions that occur in patients taking direct oral anticoagulants.
Upon completion of this course, you should be able to:
- Summarize common mechanisms of drug interactions with direct oral anticoagulants.
- Identify commonly used medications that may increase or decrease the effects of direct oral anticoagulants.
- Implement appropriate management of drug interactions with direct oral anticoagulants.
Jeff Langford, PharmD, BCPS-AQ Cardiology, BCCP, is a board-certified cardiology pharmacist with strong clinical, teaching, and interpersonal skills developed through experience in both inpatient and outpatient pharmacy. Dr. Langford is an Assistant Editor at TRC Healthcare and adjunct assistant professor at University of South Carolina College of Pharmacy. His inpatient practice includes focus in cardiovascular pharmacotherapy, and his outpatient practice includes extensive patient interaction and departmental management experience.
Contributing faculty, Jeff Langford, PharmD, BCPS-AQ Cardiology, BCCP, has disclosed no relevant financial relationship with any product manufacturer or service provider mentioned.
John M. Leonard, MD
Mary Franks, MSN, APRN, FNP-C
Randall L. Allen, PharmD
The division planners have disclosed no relevant financial relationship with any product manufacturer or service provider mentioned.
Sarah Campbell
The Director of Development and Academic Affairs has disclosed no relevant financial relationship with any product manufacturer or service provider mentioned.
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The role of implicit biases on healthcare outcomes has become a concern, as there is some evidence that implicit biases contribute to health disparities, professionals' attitudes toward and interactions with patients, quality of care, diagnoses, and treatment decisions. This may produce differences in help-seeking, diagnoses, and ultimately treatments and interventions. Implicit biases may also unwittingly produce professional behaviors, attitudes, and interactions that reduce patients' trust and comfort with their provider, leading to earlier termination of visits and/or reduced adherence and follow-up. Disadvantaged groups are marginalized in the healthcare system and vulnerable on multiple levels; health professionals' implicit biases can further exacerbate these existing disadvantages.
Interventions or strategies designed to reduce implicit bias may be categorized as change-based or control-based. Change-based interventions focus on reducing or changing cognitive associations underlying implicit biases. These interventions might include challenging stereotypes. Conversely, control-based interventions involve reducing the effects of the implicit bias on the individual's behaviors. These strategies include increasing awareness of biased thoughts and responses. The two types of interventions are not mutually exclusive and may be used synergistically.
#95010: Managing Drug Interactions with Direct Oral Anticoagulants
Direct oral anticoagulants (DOACs) are often used if oral anticoagulation is required, such as to prevent thromboembolism for patients with nonvalvular atrial fibrillation or for treatment and prevention of venous thromboembolism. One advantage of DOACs is their predictable response and limited need for routine laboratory monitoring. However, drug-drug interactions with these agents are common and may increase the risk of bleeding or thrombosis. Important DOAC interactions are often due to medications that increase bleeding propensity or affect cytochrome P450 (CYP450) enzymes or transport proteins. Clinicians require practical considerations for managing common drug interactions involving DOACs [1,2].
The characterization of drug interactions by metabolic pathways is complex. Simply because a medication interacts with one substrate of a particular cytochrome P450 pathway does not mean it affects all substrates of that isozyme. Genetics, age, nutrition, stress, liver function, hormones, and other endogenous chemicals also influence drug metabolism. Additional influences on drug interactions include dosing (e.g., dose, timing, sequence, route of administration, duration of therapy), concomitant medications, potential for a concurrent pharmacodynamic interaction (e.g., a DOAC plus aspirin), and specific drug features (e.g., narrow therapeutic index, high extraction ratio, side effect profile, multiple metabolic pathways) [3].
Pharmacokinetics can also be affected by drug transporters (e.g., P-glycoprotein, breast cancer resistance protein [BCRP], multidrug and toxin excluders [MATEs], organic anion transporting polypeptides [OATPs]). All of these proteins help move medications into or out of cells, which can impact drug absorption, distribution, or elimination [4; 5].
We are still learning about the significance of these transporters on pharmacokinetics. Most of the available data are related to P-glycoprotein (P-gp, multidrug resistance protein 1 [MDR1]). P-gp is a drug efflux pump found in the gut, liver, kidney, blood-brain barrier, and cancer cells. It pumps drugs out of cells and into the gut, bile, and/or urine for excretion [6]. Other examples include BCRP, which pumps drugs out of cells in the gut, liver, and kidney, and OATPs (e.g., OATP1B1, OATP1B3), which move drugs into the liver [5].
Generally, CYP450 interactions and drug transporter interactions involve substrates, inhibitors, and inducers. Inhibitors may increase levels of CYP450 or P-gp substrates, and inducers may decrease levels of CYP450 or P-gp substrates. For many interactions, CYP450 enzyme inhibition or induction is also involved, and P-glycoprotein substrates are often also CYP3A4 substrates, so the contribution of P-gp inhibition/induction versus CYP450 inhibition/induction can be difficult to discern [7,8,9]. For example, apixaban and rivaroxaban are metabolized by CYP3A4 (Table 1), and absorption of all DOACs is affected by P-glycoprotein (Table 2) [2,10].
SELECT CYP450-3A4 PATHWAY DRUG INTERACTIONS
DOAC Substratesc | Select Inhibitors | Select Inducers | ||||||||||||||||||||||||||||||||||||||||||||||||||
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SELECT P-GLYCOPROTEIN DRUG INTERACTIONS
DOAC Substrates | Select Inhibitors | Select Inducersa | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Drug experts from Pharmacist's Letter and Prescriber Insights provide the following practical approach to managing DOAC interactions [11]:
Pinpoint critical DOAC interactions, and act if necessary.
Generally avoid combining DOACs with strong CYP3A4 and P-glycoprotein inducers (e.g., phenytoin, rifampin, St. John's wort). These may lower DOAC levels and increase thrombosis risk.
If these interacting medications cannot be avoided, switch to warfarin, because it is easier to monitor than a DOAC.
Watch for strong CYP3A4 and P-glycoprotein inhibitors (e.g., ritonavir, itraconazole), as these may raise DOAC levels and increase bleeding risk.
To manage these drug interactions, consider the specific DOAC, dose, and indication (Table 3). One example that blends consideration of these factors is use of nirmatrelvir/ritonavir for treatment of COVID-19 in patients receiving a DOAC. This combination introduces potential risk for drug interactions, because ritonavir is a strong CYP3A4 and P-glycoprotein inhibitor. For instance, when a patient is receiving nirmatrelvir/ritonavir for COVID-19, apixaban being given for atrial fibrillation should be reduced to 2.5 mg twice per day during treatment and for three days after. However, coadministration of nirmatrelvir/ritonavir and rivaroxaban should be avoided [12].
COMPARISON OF DOACs
Drug | Approved Indications and Dosing (Adults) | Select Interactions | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Apixaban (Eliquis) |
Thromboembolism (e.g., stroke) prevention in nonvalvular atrial fibrillation: 5 mg BID or 2.5 mg BID for patients with ≥2 of the following:
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Dabigatran (Pradaxa) |
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Edoxaban (Savaysa) |
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Rivaroxaban (Xarelto) |
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BID = twice per day, CAD = coronary artery disease, CrCl = creatinine clearance, DVT = deep vein thrombosis, eGFR = estimated glomerular filtration rate, PAD = peripheral arterial disease, PE = pulmonary embolism, VTE = venous thromboembolism. |
It is also important to be aware that management of some DOAC interactions may vary based on kidney function. For example, verapamil increases DOAC levels. Rivaroxaban with verapamil should typically be avoided in patients with creatinine clearance less than 80 mL/min. In these cases, use of apixaban is acceptable [1].
Caution should be exercised when prescribing DOAC and medications that increase the risk of bleeding (e.g., antiplatelets, non-steroidal anti-inflammatory drugs [NSAIDs]). Ensuring the need for both agents is the first step. For example, aspirin used for cardiovascular primary prevention can usually be discontinued; aspirin for cardiovascular primary prevention is no longer routinely recommended, regardless of DOAC use [13; 14]. Duration of combination therapy is another concern. For instance, clopidogrel can be discontinued one-year post-stent placement for most patients with atrial fibrillation on a long-term DOAC. Limited evidence suggests that DOAC monotherapy is often sufficient at this point [15].
Managing drug-drug interactions with DOACs is of high importance to minimize preventable adverse effects. Clinicians should assess the importance of specific DOAC interactions and act to minimize their impact, if necessary. Therapeutic modification or additional monitoring may be necessary with some interactions [1,2].
Indiana University School of Medicine |
Drug Interactions Flockhart Table |
http://medicine.iupui.edu/clinpharm/ddis/table.aspx |
National Institutes of Health |
Drug-Drug Interactions Between Ritonavir-Boosted Nirmatrelvir (Paxlovid) and Concomitant Medications |
https://www.covid19treatmentguidelines.nih.gov/therapies/antivirals-including-antibody-products/ritonavir-boosted-nirmatrelvir--paxlovid-/paxlovid-drug-drug-interactions |
University of Liverpool COVID-19 Drug Interaction Checker |
https://www.covid19-druginteractions.org |
1. Wiggins BS, Dixon DL, Neyens RR, Page RL 2nd, Gluckman TJ. Select drug-drug interactions with direct oral anticoagulants: JACC Review Topic of the Week. J Am Coll Cardiol. 2020;75(11):1341-1350.
2. Herink MC, Zhuo YF, Williams CD, DeLoughery TG. Clinical management of pharmacokinetic drug interactions with direct oral anticoagulants (DOACs). Drugs. 2019;79(15):1625-1634.
3. TRC Healthcare. Clinical Resource: Cytochrome P450 (CYP) Drug Interactions. Pharmacist's Letter/Prescriber's Letter. June 2020.
4. TRC Healthcare. Clinical Resource: P-glycoprotein Drug Interactions.Pharmacist's Letter/Prescriber's Letter. June 2020.
5. Tirona RG, Kim RB. Introduction to clinical pharmacology. In: Robertson D, Williams GH (eds). Clinical and Translational Science: Principles of Human Research. 2nd ed. London: Elsevier; 2017.
6. Bailey DG. Fruit juice inhibition of uptake transport: a new type of food-drug interaction. Br J Clin Pharmacol. 2010;70(5):645-655.
7. U.S. Food and Drug Administration. Drug Development and Drug Interactions: Table of Substrates, Inhibitors and Inducers. Available at https://www.fda.gov/drugs/drug-interactions-labeling/drug-development-and-drug-interactions-table-substrates-inhibitors-and-inducers. Last accessed October 6, 2023.
8. Lin JH. Drug-drug interaction mediated by inhibition and induction of P-glycoprotein. Adv Drug Deliv Rev. 2003;55(1):53-81.
9. Akamine Y, Yasui-Furukori N, Uno T. Drug-drug interactions of P-gp substrates unrelated to CYP metabolism. Curr Drug Metab. 2019;20(2):124-129.
10. Anticoagulation Centers of Excellence. Direct Oral Anticoagulant (DOAC) Drug-Drug Interaction Guidance. Available at https://acforum-excellence.org/Resource-Center/resource_files/-2023-02-08-064454.pdf. Last accessed October 6, 2023.
11. TRC Healthcare. Know Which DOAC Interactions Require a Med Change. Pharmacist's Letter/Prescriber's Letter. May 2023.
12. Abraham S, Nohria A, Neilan TG, et al. Cardiovascular drug interactions with nirmatrelvir/ritonavir in patients with COVID-19: JACC Review Topic of the Week. J Am Coll Cardiol. 2022;80(20):1912-1924.
13. Arnett DK, Blumenthal RS, Albert MA, et al. 2019 ACC/AHA guideline on the primary prevention of cardiovascular disease: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2019;140(11):e596-e646.
14. Visseren FLJ, Mach F, Smulders YM, et al. 2021 ESC guidelines on cardiovascular disease prevention in clinical practice. Eur Heart J. 2021;42(34):3227-3337.
15. Kumbhani DJ, Cannon CP, Beavers CJ, et al. 2020 ACC expert consensus decision pathway for anticoagulant and antiplatelet therapy in patients with atrial fibrillation or venous thromboembolism undergoing percutaneous coronary intervention or with atherosclerotic cardiovascular disease: a report of the American College of Cardiology Solution Set Oversight Committee. J Am Coll Cardiol. 2021;77(5):629-658.
1. Wigle P, Bernheisel CR. Anticoagulation: updated guidelines for outpatient management. Am Fam Phys. 2019;100(7):426-434. Available at https://www.aafp.org/pubs/afp/issues/2019/1001/p426.html. Last accessed October 12, 2023.
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