Phenobarbital and Ranolazine Interaction
Drug interaction information between Phenobarbital and Ranolazine.
Phenobarbital and Ranolazine have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Phenobarbital and Ranolazine. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Phenobarbital triggers your liver to process ranolazine too quickly, meaning there won't be enough medicine in your blood.
FDA Label Information
CYP3A Inducers Do not use ranolazine with CYP3A inducers such as rifampin, rifabutin, rifapentine, phenobarbital, phenytoin, carbamazepine, and St.
Phenobarbital Also Interacts With
- Nirmatrelvir/Ritonavir major
- Voriconazole major
- Canagliflozin moderate
- Cenobamate moderate
- Clarithromycin moderate
Ranolazine Also Interacts With
- Ketoconazole major
- Carbamazepine major
- Clarithromycin major
- Rifampin major
- Phenytoin major
Frequently Asked Questions
What SPL severity band is on file for Phenobarbital + Ranolazine?
Compiled FDA labeling labels this pair major. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Phenobarbital has 59 labeled pairs on file vs Ranolazine's 31. In the major band specifically: Phenobarbital has 3 (also Nirmatrelvir/Ritonavir, Voriconazole); Ranolazine has 12 (also Ketoconazole, Carbamazepine, Clarithromycin, Rifampin).
What mechanism field is on file for Phenobarbital and Ranolazine?
Phenobarbital triggers your liver to process ranolazine too quickly, meaning there won't be enough medicine in your blood.
Ranolazine carries more major-labeled pairs than Phenobarbital
SPL source-record counts only. This page's band is major · classes on file: Phenobarbital (Anticonvulsant (Barbiturate)); Ranolazine (Late Sodium Current Inhibitor (Antianginal)).
Ranolazine has 12 major-labeled pairs vs Phenobarbital's 3.
3 major · 13 moderate · 43 minor · 59 total
- Other major peers for Phenobarbital
- Nirmatrelvir/Ritonavir
- Voriconazole
12 major · 7 moderate · 12 minor · 31 total
- Other major peers for Ranolazine
- Ketoconazole
- Carbamazepine
- Clarithromycin
- Rifampin
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.