What the FDA labels say about taking them together
Ganaxolone and phenytoin
Ganaxolone's FDA label of November 28, 2025 names phenytoin in its drug interactions section; the phenytoin labels PlainMeds reads (2) do not name ganaxolone. The ganaxolone label: “In patients on a stable ZTALMY dosage who are initiating or increasing the dosages of enzyme-inducing antiepileptic drugs, the ZTALMY dosage may need to be increased; …”
Check it at the source: the ganaxolone FDA label on DailyMed (effective November 28, 2025, Immedica Pharma US Inc); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the ganaxolone label say about phenytoin?
Ganaxolone label, drug interactionsIn patients on a stable ZTALMY dosage who are initiating or increasing the dosages of enzyme-inducing antiepileptic drugs (e.g., carbamazepine, phenytoin, phenobarbital, and primidone), the ZTALMY dosage may need to be increased; however, do not exceed the maximum daily dosage of ZTALMY [see Dosage and Administration (2.1) ].
Source: FDA drug label (ZTALMY), Immedica Pharma US Inc, effective November 28, 2025 (SPL set d91612c4-b03a-4be4-a1ee-6a13e3b83d4e), via openFDA; the full label on DailyMed
What does the phenytoin label say about ganaxolone?
Phenytoin's label (effective October 15, 2024) and its 1 other brand-application label do not name ganaxolone in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Phenytek), Mylan Pharmaceuticals Inc., effective October 15, 2024 (SPL set 0f94c791-8b07-4b41-927e-c9f28bec5f60), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Ganaxolone | Phenytoin | |
|---|---|---|
| Labeled for | n/a | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.145 per capsule 100 mg capsule |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once