Capsule
- Strengths
- 250, 500 mg
- Product note
- Swallow whole with a meal.
Stiripentol
Diacomit
DailyMed-verified antiseizure indications
Indication / use
- Label / evidence summary
- Diacomit: Dravet syndrome-associated seizures in patients taking clobazam, aged at least 6 months and weighing at least 7 kg. The label does not support monotherapy.
- Role
- Maintenance
- Class
- Non-benzodiazepine-site GABA-A potentiation plus inhibition of clobazam metabolism
Indications checked 26 September 2026. Product, route, age, and treatment-role limits apply. A DailyMed listing alone does not establish FDA approval.
- Diacomit capsule/powder U.S. label
Dravet syndrome · 6 months and older · MaintenanceOnly with clobazam and body weight ≥7 kg.
Formulations & strengths
U.S. products unless another country is named. Strengths are per unit or stated volume.
Powder packets for oral suspension
- Strengths
- 250 mg; 500 mg per packet
- Product note
- U.S. label: mix the prescribed packet dose in 100 mL water, take immediately with a meal, then rinse the cup with 25 mL water and drink. A single 250 mg or 500 mg packet in 100 mL gives a nominal 2.5 or 5 mg/mL mixture; administer the whole prescribed preparation, not a partial aliquot.
Brand & formulation labels
Each link names the product and formulation it covers. Archived labels do not establish current availability.
Dosing & administration
- Adult / product-specific schedule
- 50 mg/kg/day divided 2–3 times; max 3,000 mg/day.
- Pediatric
- Age 6 months–<1 year (≥7 kg), or age ≥1 year and 7–<10 kg: 25 mg/kg twice daily only. Age ≥1 year and ≥10 kg: 25 mg/kg twice daily or 16.67 mg/kg three times daily. Total 50 mg/kg/day; maximum 3,000 mg/day. Do not use three-times-daily dosing in the younger/lower-weight groups.
- Titration / repeat dosing
- Use the age/weight-specific frequency: twice daily only if <1 year or <10 kg. Total recommended dose 50 mg/kg/day, maximum 3,000 mg/day. Product-strength rounding and co-medication reductions require the full label.
Dose adjustment & concentrations
- Renal impairment
- Not recommended moderate/severe impairment.
- Hepatic impairment
- Not recommended moderate/severe impairment.
- Serum reference information
- No established therapeutic range
Safety
- Boxed warning
- No boxed warning.
- Contraindications
- None listed in the linked U.S. label.
- Serious precautions & monitoring
- Obtain hematologic testing before treatment and every 6 months for neutropenia/thrombocytopenia. Monitor appetite, growth/weight and sedation, particularly with clobazam. Suspension contains phenylalanine; check phenylketonuria precautions.
Common / selected adverse effects
- Somnolence
- Decreased appetite
- Agitation
- Ataxia
- Weight decrease
- Neutropenia
Drug interactions: toxicity & clinical action
| Partner / combination | Clinical effect | Clinical action |
|---|---|---|
| Clobazam | Raises clobazam and active N-desmethylclobazam concentrations, often increasing somnolence. | Label recommends an initial 25% clobazam reduction for somnolence; consider a further 25% if it persists. |
| Fenfluramine with clobazam | Requires lower fenfluramine maximum. | Use the fenfluramine stiripentol/clobazam regimen and its 17 mg/day ceiling. |
| CYP2C19/2C8, P-gp/BCRP and other susceptible substrates / strong inducers | Substrate toxicity can increase; inducers can reduce stiripentol. | Check the exact partner and reduce/monitor as directed by label; avoid strong inducers when possible. |
Pregnancy & contraception
- Fetal / neonatal risk
- Human stiripentol pregnancy data are inadequate. Animal studies found fetal malformations, developmental loss and impaired growth at maternal doses below the recommended clinical dose.
Clinical evidence
Research summaries describe studied populations and outcomes; they do not add indications or constitute treatment recommendations.
Direct pivotal trial
Trial summary
- Study design / duration
- Two multicenter, randomized, double-blind, placebo-controlled add-on trials in small pediatric Dravet syndrome cohorts already receiving clobazam and valproate; 2-month treatment followed 1-month baseline.
- Primary endpoint
- Sticlo France month 2: median change −91% vs +7.4% placebo; Italy −81% vs −27%. Ages 3–<18, Dravet syndrome on clobazam + valproate; 50 mg/kg/day.
- Results
- STICLO France and Italy used a >50% reduction in clonic/tonic-clonic seizures as the responder threshold: 71% and 67% with stiripentol versus 5% and 9% with placebo, added to clobazam and valproate.
- Responder rate
- Trial definition was >50% reduction (not ≥50%): France 15/21 (71%) vs 1/20 (5%); Italy 8/12 (67%) vs 1/11 (9.1%). Double-blind treatment 2 months.
- Seizure freedom
- 43% (France) and 25% (Italy) reported no generalized clonic/tonic-clonic seizures during study; not freedom from all seizure types. Label §14.
Trial publications
Mechanism of action
- Human antiseizure mechanism is incompletely established. Electrophysiology shows direct GABA-A positive allosteric modulation at a site distinct from the classical benzodiazepine site.
- Neuronal experiments show longer channel openings (a barbiturate-like kinetic effect); this does not establish that stiripentol shares the phenobarbital binding site.
- Recombinant studies show subunit dependence, with stronger α3 responses and activity at δ-containing receptors lacking the γ subunit required for classical benzodiazepine modulation. These are preclinical findings, not proven clinical selectivity.
- Separately inhibits CYP3A4/CYP2C19, raising clobazam and active norclobazam concentrations. Direct receptor potentiation and this pharmacokinetic interaction can both contribute; monitor sedation and adjust clobazam per label.
Pharmacology
Adult values unless specified. Vd/F denotes apparent oral distribution volume.
Pharmacokinetics
- Bioavailability
- Absolute bioavailability is unknown. Oral absorption is substantial; capsule and powder AUCs were comparable in one study, but powder peak concentrations were higher.
- Elimination half-life
- Adult single-dose studies: 4.5–13 hours, increasing with dose. Pediatric Dravet syndrome population model: 8.5 hours at 10 kg to 23.5 hours at 60 kg during combination therapy.
- Volume of distribution
- Apparent volume in the pediatric Dravet syndrome model: 32.0 L at 10 kg to 191.8 L at 60 kg (approximately 3.2 L/kg), on valproate/clobazam combination therapy.
- Active metabolite(s)
- No clinically established active stiripentol metabolite. Increased active norclobazam results from inhibition of clobazam metabolism, not from conversion of stiripentol to norclobazam.
- Active-metabolite half-life
- Not applicable — no clinically established active metabolite.
- Protein binding
- ~99%
- Metabolism / elimination
- CYP1A2, 2C19, and 3A4; strong inhibitor
Nonlinear, time-dependent clearance means a single adult half-life is an incomplete description of pediatric combination treatment.
Molecular structure
NIH PubChem structure and record ↗
Product history
- Initial U.S. approval
- 2018
- Market / formulation history
- 2018 in the U.S.
- Brands
- Diacomit
- Manufacturer / marketer
- Biocodex (Diacomit)
- Generic availability
- No
- Related drugs
- Often used with clobazam; interaction is central to its clinical effect.
Sources & review status
Indications and DailyMed PDFs checked: 2026-09-26. Other profile sources reviewed: 2026-09-15 · label revision noted at that review: 4/2026. This is a draft reference; final review is pending.