What the FDA labels say about taking them together
Ganaxolone and primidone
Ganaxolone's FDA label of November 28, 2025 names primidone in its drug interactions section; the primidone label PlainMeds reads does 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 primidone FDA label on DailyMed (effective September 10, 2026, Bausch Health US, LLC).
What does the ganaxolone label say about primidone?
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 primidone label say about ganaxolone?
Primidone's label (effective September 10, 2026) does 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 (Mysoline), NDA009170 (Valeant), as published by Bausch Health US, LLC, effective September 10, 2026 (SPL set af593171-dabb-4ea3-b44c-89ed457b2c46), 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 | Primidone | |
|---|---|---|
| Labeled for | n/a | Seizures and epilepsy |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.0914 per tablet 50 mg tablet |
| 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