Drug Interaction Report

Phenytoin and Bromfenac Ophthalmic: Interaction Details

A pharmacist-reviewed analysis of the Phenytoin and Bromfenac Ophthalmic 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

Phenytoin

Dilantin Phenytek
+

Bromfenac Ophthalmic

Bromday® Bromsite Bromsite® Prolensa Prolensa® Xibrom®
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
Moderate
Can be significant — usually manageable with 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 237 documented Phenytoin interactions, 38 are rated moderate — including this one.
Onset
delayed
Evidence
theoretical
Severity
Moderate

What happens

Decreased bromfenac efficacy

Interaction Deep Dive

Concurrent use of bromfenac and phenytoin has resulted in decreased mean plasma levels of bromfenac. However, the pharmacokinetic parameters of phenytoin were not changed significantly1. Phenytoin is an inducer of cytochrome P450 drug-metabolizing enzymes. The precise isoenzyme of the CYP P450 system which metabolizes bromfenac has not been identified, but it is possible that phenytoin alters the bioavailability of bromfenac by inducing its metabolism 2.

Why it happens (mechanism)

Induction of bromfenac metabolism by phenytoin

Literature reports

1 report — tap to read

a) In an open-label, non-randomized, inpatient study, 12 healthy male volunteers received bromfenac 50 mg every 8 hours for 3 days, followed by phenytoin at a dose to produce trough concentrations between 7 mg/L and 14 mg/L. Once the phenytoin dose was established, bromfenac 50 mg every 8 hours was again administered and continued for 7 days. The mean bromfenac Cmax decreased by about 40% (4.80 mg/L vs 2.77 mg/L) when phenytoin was coadministered. The bromfenac AUC was 6.61 mg x hr/L when administered alone, and decreased to 3.79 mg x hr/L when phenytoin was added to therapy. In addition, the oral clearance of bromfenac doubled (0.11 L/hr/kg vs 0.22 L/hr/kg) and the volume of distribution increased by 77% (0.22 L/kg vs 0.39 L/kg) with phenytoin administration. The mean peak serum concentration and AUC of phenytoin were increased by 9% and 11%, respectively, in the presence of bromfenac 1.

Common questions

Can I take Phenytoin and Bromfenac Ophthalmic together?

Decreased bromfenac efficacy Always confirm with your pharmacist or prescriber before making any change.

How serious is the Phenytoin and Bromfenac Ophthalmic interaction?

It is rated moderate. Can be significant — usually manageable with monitoring.

How quickly could this interaction happen?

The documented onset is "delayed". Effects tend to build up gradually over days to weeks.

How strong is the evidence for this interaction?

The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

  • Does my dose of Phenytoin or Bromfenac Ophthalmic 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 anything you'd monitor while I'm on both?

References (2)

  1. Gumbhir-Shah K, Cevallos WH, DeCleene SA, et al: Evaluation of pharmacokinetic interaction between bromfenac and phenytoin in healthy males. J Clin Pharmacol 1997; 37:160-168. DOI
  2. Product Information: Duract(TM), bromfenac sodium. Wyeth Laboratories Inc. Philadelphia, PA, 1997. DailyMed
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Phenytoin

Keep reading about Phenytoin

All Phenytoin interactions (237)
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Bromfenac Ophthalmic

Keep reading about Bromfenac Ophthalmic

All Bromfenac Ophthalmic interactions (253) Bromfenac Ophthalmic drug information
Also serious with: Ketorolac Xipamide Phenindione Pentoxifylline
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:

Phenytoin + 1,4-butanediol Activated Charcoal Beer Gamma-hydroxybutyrate (ghb) Kava L-tryptophan Siberian Cocklebur St. John's Wort + 216 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.