Ztalmy (ganaxolone)
An approved treatment for CDKL5 Deficiency Disorder.
The same compound appears under different names depending on the context. Here is how to identify Ganaxolone wherever you encounter it, plus the key facts at a glance.
- Generic name
- Ganaxolone
- Brand name
- Ztalmy
- Drug class
- Neuroactive steroid (GABA-A modulator)
- Manufacturer
- Immedica Pharma
- How it's taken
- Given by mouth three times a day as a cherry-flavored oral suspension.
The first and only FDA-approved treatment specifically for seizures associated with CDKL5 deficiency disorder (CDD). Ganaxolone enhances inhibitory signaling in the brain by boosting the activity of GABA-A receptors, the brain's main calming system.
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How Ganaxolone works
CDKL5 deficiency disorder causes severe, treatment-resistant seizures starting in infancy. The brain's main 'brake' on overactive electrical signaling is the GABA-A receptor system, and one of the body's own modulators of that system, allopregnanolone, is thought to be reduced or dysregulated in CDD. Ganaxolone is a synthetic analog of allopregnanolone that binds to a separate site on the GABA-A receptor and amplifies the calming effect of GABA, raising the seizure threshold without acting like a traditional anti-seizure medication.
Mechanism: Neuroactive steroid that acts as a positive allosteric modulator at synaptic and extrasynaptic GABA-A receptors
Side effects and safety
The most common side effects in the CDD pivotal trial were somnolence (sleepiness), fever, salivation, and seasonal allergy symptoms. Serious risks include depression of the central nervous system (additive with other sedating medications including alcohol and opioids) and suicidal thoughts or behavior, which the label flags as a class effect across antiseizure medications. Sudden withdrawal can increase seizure frequency, so dose changes are tapered.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Ganaxolone
Given by mouth three times a day as a cherry-flavored oral suspension. It must be taken with food, three times a day. Doses are weight-based and increased in steps every 7 days, reaching the full dose after about 4 weeks. The maximum is 63 mg/kg a day for patients weighing 28 kg or less, and 1,800 mg a day for patients over 28 kg. Store at room temperature (68 to 77 F) upright in the original bottle, and use within 30 days of opening. It is a Schedule V controlled substance.
Help paying for Ztalmy
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
Eligible commercially insured patients may pay as low as $0 per fill (up to 30-day supply); annual maximum applies.
For: private insurance · source - Insurance and case manager help
A Patient Care Coordinator confirms insurance coverage, schedules specialty pharmacy delivery and discusses out-of-pocket costs.
The official page does not say who qualifies. Ask the program. · source
Good to know: Program sponsor is Immedica Pharma US Inc. State and federal health program beneficiaries are not eligible for the copay program, even if they pay cash. Answer calls from 1-844-982-5691 to avoid delivery delays.
Clinical trial results
The Marigold study (NCT03572933) was the Phase 3, double-blind, placebo-controlled trial in 101 patients aged 2-19 with CDD. Patients on ganaxolone had a median 30.7% reduction in 28-day major motor seizure frequency vs. 6.9% on placebo over the 17-week double-blind period, a statistically significant difference. Open-label extension data showed responses sustained beyond one year for a meaningful subset of patients.
Development history
Ganaxolone was studied across multiple seizure indications over more than two decades. Marinus Pharmaceuticals focused development on rare genetic epilepsies, and the FDA approved ZTALMY on March 18, 2022 for seizures in CDD patients aged 2 and older. It was the first medicine specifically approved for any CDD symptom. After Phase 3 setbacks in other indications, Marinus was acquired by Sweden-based Immedica Pharma AB in a deal completed on February 11, 2025, transferring global rights to ZTALMY. Immedica became the EU marketing authorization holder in June 2025, and ZTALMY remains on the U.S. market.
Explore CDKL5 Deficiency Disorder trials
Common questions about Ganaxolone
▸What is Ganaxolone (Ztalmy)?
The first and only FDA-approved treatment specifically for seizures associated with CDKL5 deficiency disorder (CDD). Ganaxolone enhances inhibitory signaling in the brain by boosting the activity of GABA-A receptors, the brain's main calming system.
▸How does Ganaxolone work?
CDKL5 deficiency disorder causes severe, treatment-resistant seizures starting in infancy. The brain's main 'brake' on overactive electrical signaling is the GABA-A receptor system, and one of the body's own modulators of that system, allopregnanolone, is thought to be reduced or dysregulated in CDD. Ganaxolone is a synthetic analog of allopregnanolone that binds to a separate site on the GABA-A receptor and amplifies the calming effect of GABA, raising the seizure threshold without acting like a traditional anti-seizure medication.
▸What are the side effects of Ganaxolone?
The most common side effects in the CDD pivotal trial were somnolence (sleepiness), fever, salivation, and seasonal allergy symptoms. Serious risks include depression of the central nervous system (additive with other sedating medications including alcohol and opioids) and suicidal thoughts or behavior, which the label flags as a class effect across antiseizure medications. Sudden withdrawal can increase seizure frequency, so dose changes are tapered.
▸How is Ganaxolone taken?
Given by mouth three times a day as a cherry-flavored oral suspension. It must be taken with food, three times a day. Doses are weight-based and increased in steps every 7 days, reaching the full dose after about 4 weeks. The maximum is 63 mg/kg a day for patients weighing 28 kg or less, and 1,800 mg a day for patients over 28 kg. Store at room temperature (68 to 77 F) upright in the original bottle, and use within 30 days of opening. It is a Schedule V controlled substance.
▸Is Ganaxolone FDA approved?
Yes, Ganaxolone (Ztalmy) is FDA approved (2022) for the treatment of CDKL5 Deficiency Disorder.
▸What is CDKL5 deficiency disorder?
CDD is a rare genetic developmental and epileptic encephalopathy caused by mutations in the CDKL5 gene on the X chromosome. Children typically present with severe seizures in the first months of life, profound developmental delay, vision impairment, and movement problems. Seizures are often resistant to standard antiseizure medications.
▸How is ZTALMY different from other antiseizure medications?
Most antiseizure medications act on sodium channels, calcium channels, or the synaptic GABA-A receptor. Ganaxolone is a neuroactive steroid that targets both synaptic and extrasynaptic GABA-A receptors, the latter of which traditional benzodiazepines do not reach. That broader receptor coverage is the basis for using it after other medications have failed.
▸Is ZTALMY a cure for CDD?
No. ZTALMY treats seizures but does not address the underlying CDKL5 gene defect or the developmental and motor features of CDD. Several gene therapy and gene replacement approaches for CDD are in early development but none are yet approved.
▸Can ZTALMY be combined with other seizure medications?
Yes, and almost all patients in the Marigold trial (96%) were already taking 1 to 4 other antiseizure medications when ZTALMY was added. Because ganaxolone can be sedating, combinations with other CNS depressants (especially benzodiazepines and opioids) need careful dose adjustment to avoid excessive sleepiness or respiratory depression.
▸How quickly do families see a response?
In the Marigold trial, separation from placebo emerged within the first month of treatment after dose titration. Some families report seizure reductions sooner; others see benefit only after several weeks at full dose. Response is variable and the label does not promise efficacy in every patient.