Ubrelvy and Phenytoin Should Not Be Used Together
Concomitant use of ubrelvy (ubrogepant) with phenytoin should be avoided because phenytoin is a strong CYP3A4 inducer that will significantly reduce ubrogepant blood levels, resulting in loss of efficacy for migraine treatment. 1
The Drug Interaction Mechanism
Ubrogepant is metabolized primarily through the CYP3A4 enzyme pathway. Phenytoin is classified as a strong CYP3A4 inducer, meaning it accelerates the breakdown of ubrogepant in the liver. The FDA label for ubrelvy explicitly states that "In patients taking strong CYP3A4 inducers (e.g., phenytoin, barbiturates, rifampin, St. John's Wort), loss of ubrogepant efficacy is expected, and concomitant use should be avoided." 1
When rifampin (another strong CYP3A4 inducer like phenytoin) was studied with ubrogepant, it caused a significant reduction in ubrogepant exposure—meaning the medication levels dropped substantially and would not provide adequate migraine relief 1.
Clinical Implications
- Ubrelvy will not work effectively if taken with phenytoin
- The patient will experience treatment failure for their migraine attacks
- There is no dose adjustment that can overcome this interaction—the combination simply should not be used
Alternative Approaches
If a patient requires both migraine treatment and phenytoin for seizure control:
For acute migraine treatment while on phenytoin, consider:
- Triptans (sumatriptan, rizatriptan, eletriptan) combined with NSAIDs or acetaminophen—these are first-line recommendations and not affected by phenytoin 2, 3
- Aspirin-acetaminophen-caffeine combination (strong recommendation) 3
- NSAIDs alone (ibuprofen, naproxen) or acetaminophen for milder attacks 2, 3
- Intranasal or subcutaneous formulations if nausea/vomiting is prominent 2
Avoid other gepants (rimegepant, zavegepant) as they share the same CYP3A4 metabolism pathway and will have similar interactions with phenytoin.
Critical Pitfall to Avoid
Do not attempt to increase the ubrelvy dose to compensate for the interaction—this will not overcome the enzymatic induction caused by phenytoin and is not supported by any evidence. The FDA label provides no alternative dosing strategy for strong inducers; it simply recommends avoidance 1.