Drug Interaction Report

Primidone and Esomeprazole Injection: Interaction Details

A pharmacist-reviewed analysis of the Primidone and Esomeprazole Injection interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Primidone

Mysoline
+

Esomeprazole Injection

Nexium Nexium I.V.®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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.

Of 204 documented Primidone interactions, 190 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
unspecified
Evidence
theoretical
Severity
Major

What happens

Reduced esomeprazole exposure, reduced efficacy of esomeprazole, increased PHENobarbital exposure and an increased risk of PHENobarbital-related adverse effects

Interaction Deep Dive

Concomitant use of PHENobarbital (a CYP2C19 inducer) with esomeprazole (a CYP2C19 substrate) may decrease esomeprazole exposure, which may reduce the efficacy of esomeprazole. If concomitant use cannot be avoided, closely monitor neonates and consider increasing the esomeprazole dosage accordingly. Also, the concomitant use of PHENobarbital (a CYP2C19 substrate) with esomeprazole (a CYP2C19 inhibitor) may increase PHENobarbital exposure, which may increase the risk of PHENobarbital-related adverse reactions. If concomitant use cannot be avoided, closely monitor for adverse reactions and consider titration of the PHENobarbital maintenance dosage accordingly1.

Why it happens (mechanism)

Induction of CYP2C19-mediated metabolism of esomeprazole; inhibition of CYP2C19-mediated metabolism of PHENobarbital

Common questions

Can I take Primidone and Esomeprazole Injection together?

Reduced esomeprazole exposure, reduced efficacy of esomeprazole, increased PHENobarbital exposure and an increased risk of PHENobarbital-related adverse effects Always confirm with your pharmacist or prescriber before making any change.

How serious is the Primidone and Esomeprazole Injection 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 Primidone or Esomeprazole Injection 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 (1)

  1. Product Information: SEZABY(TM) intravenous injection, phenobarbital sodium intravenous injection. Sun Pharmaceutical Industries Inc (per manufacturer), Cranbury, NJ, 2022. DailyMed
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Primidone

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All Primidone interactions (204)
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Esomeprazole Injection

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All Esomeprazole Injection interactions (95) Esomeprazole Injection drug information
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Beyond drug–drug

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:

Primidone + 1,4-butanediol Activated Charcoal Beer Gamma-hydroxybutyrate (ghb) Kava L-tryptophan Wine 5-htp + 116 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.