Dabigatran and Primidone: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Primidone
Dabigatran
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Reduced dabigatran exposure and increased risk of thrombotic events
Interaction Deep Dive
Concomitant use of dabigatran with phenobarbital, a CYP3A4 inducer, or primidone (the prodrug of phenobarbital), may lead to reduced dabigatran levels, especially in the presence of other drugs that may cause reduced dabigatran levels, and should be undertaken with caution1. Avoid coadministration if possible and consider the use of vitamin-K antagonists in patients requiring enzyme-inducing antiseizure medications 2.
Why it happens (mechanism)
Induction of CYP3A4-mediated dabigatran metabolism; possible induction of P-glycoprotein-mediated efflux transport of dabigatran
Literature reports
2 reports — tap to read
a) There was no difference in the risk of thromboembolic events in a retrospective cohort study of propensity score-matched adults (n=14,078 eligible episodes) taking direct-acting oral anticoagulant (DOAC) therapy (apixaban, dabigatran, or rivaroxaban) concomitantly with enzyme-inducing antiseizure medications (EI-ASMs), including carbamazepine, oxcarbazepine, phenobarbital, phenytoin, primidone, or topiramate, compared with non-EI-ASMs (adjusted HR, 1.1 [95% CI, 0.82 to 1.46]). In a secondary analysis (n=14,158 eligible episodes), there was a significant reduction in major bleeding events with concomitant use of DOACs with EI-ASMs compared with non-EI-ASMs (adjusted HR, 0.63 [95% CI, 0.44 to 0.89]) 3.
b) In a retrospective study (N=131) of patients receiving primidone (n=4) or other enzyme-inducing antiseizure medications (EI-ASM; n=22) concomitantly with direct oral anticoagulant (DOAC) therapy, 37.5% experienced DOAC concentrations below the therapeutic range compared with 9.3% who were not receiving primidone or other enzyme-inducing antiseizure medications (OR, 5.82; 95% CI, 2.03 to 16.66). Dabigatran was used by 4.6% (6 patients) of patients within the study; some patients received rivaroxaban (14 patients) or apixaban (111 patients) 2.
Common questions
Can I take Dabigatran and Primidone together?
Reduced dabigatran exposure and increased risk of thrombotic events Always confirm with your pharmacist or prescriber before making any change.
How serious is the Dabigatran and Primidone interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Dabigatran or Primidone need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (3)
- Steffel J, Collins R, Antz M, et al: 2021 European Heart Rhythm Association Practical Guide on the use of non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation. Europace 2021; 23(10):1612-1676.
- Perlman A, Goldstein R, Choshen Cohen L, et al: Effect of enzyme-inducing antiseizure medications on the risk of sub-therapeutic concentrations of direct oral anticoagulants: a retrospective cohort study. CNS Drugs 2021; 35(3):305-316. PubMed
- Acton EK, Hennessy S, Gelfand MA, et al: Direct-acting oral anticoagulants and antiseizure medications for atrial fibrillation and epilepsy and risk of thromboembolic events. JAMA Neurol 2024; Epub:Epub. PubMed
Keep reading about Primidone
Keep reading about Dabigatran
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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