Clobazam

The exact mechanism of action for clobazam, a 1,5-benzodiazepine, is not fully understood but is thought to involve potentiation of GABAergic neurotransmission resulting from binding at the benzodiazepine site of the GABA A receptor.

• Clobazam oral suspension is indicated for the adjunctive treatment of seizures associated with Lennox-Gastaut syndrome (LGS) in patients 2 years of age or older.ICD-10: G40.909

• Clobazam oral suspension is contraindicated in patients with a history of hypersensitivity to the drug or its ingredients. Hypersensitivity reactions have included serious dermatological reactions [see Warnings and Precautions ( 5.6 , 5.7 )].contraindicated

For doses above 5 mg/day administer in two divided doses ( 2.1 ) Patients ≤30 kg body weight: Initiate at 5 mg daily and titrate as tolerated up to 20 mg daily ( 2.1 ) Patients greater than 30 kg body weight: Initiate at 10 mg daily and titrate as tolerated up to 40 mg daily ( 2.1 ) Dosage adjustment needed in following groups: o Geriatric patients ( 2.4 , 8.5 ) o Known CYP2C19 poor metabolizers ( 2.5 ) o Mild or moderate hepatic impairment; no information for severe hepatic impairment ( 2.7 , 8.8 ) Measure prescribed amount of oral suspension using provided adapter and dosing syringe ( 2.3 ) Oral suspension: Can be taken with or without food ( 2.3 ) 2.1 Dosing Information A daily dose of clobazam oral suspension greater than 5 mg should be administered in divided doses twice daily; a 5 mg daily dose can be administered as a single dose. Dose patients according to body weight. Individualize dosing within each body weight group, based on clinical efficacy and tolerability. Each dose in Table 1 (e.g., 5 to 20 mg in ≤30 kg weight group) has been shown to be effective, although effectiveness increases with increasing dose [see Clinical Studies ( 14 )]. Do not proceed with dose escalation more rapidly than weekly, because serum concentrations of clobazam and its active metabolite require 5 and 9 days, respectively, to reach steady-state. Table 1.

Somnolence or Sedation: Monitor for central nervous system (CNS) depression. Risk may be increased with concomitant use of other CNS depressants ( 5.4 , 5.5 ) Serious Dermatological Reactions (including Stevens-Johnson syndrome and toxic epidermal necrolysis): Discontinue clobazam oral suspension at first sign of rash unless the rash is clearly not drug-related ( 5.6 ) Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity: Discontinue if no alternative etiology ( 5.7 ) Suicidal Behavior and Ideation: Monitor for suicidal thoughts or behaviors ( 5.8 ) Neonatal Sedation and Withdrawal Syndrome: Clobazam use during pregnancy can result in neonatal sedation and/or neonatal withdrawal ( 5.9 , 8.1 ) 5.1 Risks from Concomitant Use with Opioids Concomitant use of benzodiazepines, including clobazam oral suspension, and opioids may result in profound sedation, respiratory depression, coma, and death. Because of these risks, reserve concomitant prescribing of benzodiazepines and opioids for patients for whom alternative treatment options are inadequate. Observational studies have demonstrated that concomitant use of opioid analgesics and benzodiazepines increases the risk of drug-related mortality compared to use of opioids alone. If a decision is made to prescribe clobazam oral suspension concomitantly with opioids, prescribe the lowest effective dosages and minimum durations of concomitant use, and follow patients closely for signs and symptoms of respiratory depression and sedation.

Clinically significant adverse reactions that appear in other sections of the labeling include the following: Risks from Concomitant Use with Opioids [see Warnings and Precautions ( 5.1 )] Abuse, Misuse, and Addiction [see Warnings and Precautions (5.2)] Dependence and Withdrawal Reactions [see Warnings and Precautions ( 5.3 )] Potentiation of Sedation from Concomitant Use with Central Nervous System Depressants [see Warnings and Precautions ( 5.4 )] Somnolence or Sedation [see Warnings and Precautions ( 5 .5 )] Serious Dermatological Reactions [see Contraindications ( 4 ), Warnings and Precautions ( 5.6 )] Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity [see Warnings and Precautions ( 5.7 )] Suicidal Behavior and Ideation [see Warnings and Precautions ( 5.8 )] Neonatal Sedation and Withdrawal Syndrome [see Warnings and Precautions ( 5.9 )] Adverse reactions that occurred at least 10% more frequently than placebo in any clobazam oral suspension dose included constipation, somnolence or sedation, pyrexia, lethargy, and drooling ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Ascend Laboratories, LLC at 1-877-272-7901 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Pregnancy: Based on animal data, may cause fetal harm ( 8.1 ) 8.1 Pregnancy Pregnancy Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to AEDs, such as clobazam, during pregnancy. Healthcare providers are encouraged to recommend that pregnant women taking clobazam enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry by calling 1-888-233-2334 or online at http://www.aedpregnancyregistry.org/. Risk Summary Neonates born to mothers using benzodiazepines late in pregnancy have been reported to experience symptoms of sedation and/or neonatal withdrawal [see Warnings and Precautions ( 5.9 ) and Clinical Considerations]. Available data from published observational studies of pregnant women exposed to benzodiazepines do not report a clear association with benzodiazepines and major birth defects (see Data). Administration of clobazam to pregnant rats and rabbits during the period of organogenesis or to rats throughout pregnancy and lactation resulted in developmental toxicity, including increased incidences of fetal malformations and mortality, at plasma exposures for clobazam and its major active metabolite, N-desmethylclobazam, below those expected at therapeutic doses in patients [see Animal Data] .

Metabolism

The peak plasma levels (C max ) and the area under the curve (AUC) of clobazam are dose-proportional over the dose range of 10 to 80 mg following single- or multiple-dose administration of clobazam oral suspension. Based on a population pharmacokinetic analysis, the pharmacokinetics of clobazam are linear from 5 to 160 mg/day.

Overdosage of benzodiazepines is characterized by central nervous system depression ranging from drowsiness to coma. In mild to moderate cases, symptoms can include drowsiness, confusion, dysarthria, lethargy, hypnotic state, diminished reflexes, ataxia, and hypotonia. Rarely, paradoxical or disinhibitory reactions (including agitation, irritability, impulsivity, violent behavior, confusion, restlessness, excitement, and talkativeness) may occur. In severe overdosage cases, patients may develop respiratory depression and coma. Overdosage of benzodiazepines in combination with other CNS depressants (including alcohol and opioids) may be fatal [see Warnings and Precautions ( 5.2 )] . Markedly abnormal (lowered or elevated) blood pressure, heart rate, or respiratory rate raise the concern that additional drugs and/or alcohol are involved in the overdosage. In managing benzodiazepine overdosage, employ general supportive measures, including intravenous fluids and airway maintenance.

• Oct 21, 2011NDANDA202067Lundbeck Pharms Llc
• Dec 14, 2012NDANDA203993Lundbeck Pharms Llc
• Oct 22, 2018ANDAANDA209687Upsher Smith Labs
• Oct 22, 2018ANDAANDA210039Amneal
• Oct 22, 2018ANDAANDA209718Amneal Pharms Co
• Oct 22, 2018ANDAANDA209440Taro
• Oct 22, 2018ANDAANDA209795Hetero Labs Ltd Iii
• Nov 1, 2018NDANDA210833Assertio Speclty

1. 1Seizure4,78820%
2. 2Drug Ineffective3,07813%
3. 3Off Label Use2,1469.0%
4. 4Somnolence1,8787.9%
5. 5Drug Interaction1,1474.8%
6. 6Fatigue1,1274.8%
7. 7Epilepsy8253.5%
8. 8Condition Aggravated8083.4%
9. 9Status Epilepticus7163.0%
10. 10Product Use In Unapproved Indication7013.0%
11. 11Pneumonia6912.9%
12. 12Fall6502.7%
13. 13Decreased Appetite6362.7%
14. 14Aggression6322.7%
15. 15Generalised Tonic-clonic Seizure6252.6%

Recent PubMed references pinned to Clobazam as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Early sedation-related adverse events with the cenobamate-clobazam combination in drug-resistant epilepsy: real-world preliminary observations.
  Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology · 2026 · Falcicchio G, Delmonte V, Francavilla T, et al.
  PMID 42014614DOI 10.1007/s10072-026-09048-7
• Effectiveness of adjunctive low-dose clobazam in adults with focal drug-resistant epilepsy and incomplete response to cenobamate: A real-world study.
  Epilepsia open · 2026 · Ciullo I, D'Aniello A, Panzini C, et al.
  PMID 41919359DOI 10.1002/epi4.70261
• Therapeutic Drug Monitoring of Clobazam, Perampanel, and Lacosamide Using a UPLC-MS/MS Method: Analysis of 5-Year Experience in a Large Cohort of Pediatric Epilepsy Patients From China.
  Biomedical chromatography : BMC · 2026 · Zhao T, Zhang HL, Yu J, et al.
  PMID 41755370DOI 10.1002/bmc.70403
• Efficacy and Safety of Clobazam Adjunctive Therapy in Pediatric Patients with Drug-Resistant Epilepsy.
  Drug design, development and therapy · 2025 · Yu L, Chen S, Zhang Z, et al.
  PMID 41393325DOI 10.2147/DDDT.S560731
• Sleep, BDNF, and beyond: A comparative study of zolpidem and clobazam in insomnia treatment.
  Sleep medicine · 2026 · Kumar V, Halder S, Srivastava S, et al.
  PMID 41197179DOI 10.1016/j.sleep.2025.106893
• Clobazam versus corticosteroid for developmental and epileptic encephalopathy with spike-wave activation in sleep ((D)EE-SWAS): Results of a multicenter observational study.
  Epilepsia · 2026 · van Arnhem MML, Vijn LJ, Rubboli G, et al.
  PMID 41133317DOI 10.1111/epi.18680
• Which are the options and dosages for clobazam shortages on epilepsy treatment? Review of literature and survey of specialists.
  Arquivos de neuro-psiquiatria · 2025 · Pinto LF, Mendonça GS, Guerreiro CAM, et al.
  PMID 40921412DOI 10.1055/s-0045-1811235
• Caregiver-reported non-seizure and seizure outcomes with cannabidiol and clobazam in patients aged ≥2 years with Lennox-Gastaut syndrome or Dravet syndrome: A subgroup analysis of the BECOME survey.
  Seizure · 2025 · Perry MS, Dixon-Salazar T, Meskis MA, et al.
  PMID 40354745DOI 10.1016/j.seizure.2025.04.017

The 10 most recently updated of 27 ClinicalTrials.gov registrations naming Clobazam as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Pharmacokinetics, Pharmacodynamics, and Safety Profile of Understudied Drugs Administered to Children Per Standard of Care (POPS)
  Recruiting · Observational · 5,000 enrolled · Duke University
  NCT04278404updated 2026-04-06
• Population Pharmacokinetics of Antiepileptic in Pediatrics
  Completed · Observational · 753 enrolled · Assistance Publique - Hôpitaux de Paris
  NCT03196466updated 2025-11-20
• GABA Pathways in Autism Spectrum Disorder (ASD)
  Completed · Interventional · 109 enrolled · King's College London
  NCT03678129updated 2025-08-26
• The Benefit and Safety of Older Generation Anti-Epileptic Drugs (AEDs) in Drug-Resistant Epilepsy Children
  Unknown · Phase 4 · Interventional · 100 enrolled · Dr Cipto Mangunkusumo General Hospital
  NCT05697614updated 2023-01-26
• A Randomized Controlled Trial to Investigate Possible Drug-drug Interactions Between Clobazam and Cannabidiol
  Completed · Phase 2 · Interventional · 20 enrolled · Jazz Pharmaceuticals
  NCT02565108updated 2022-09-28
• An Open-label Extension Study to Investigate Possible Drug-drug Interactions Between Clobazam and Cannabidiol
  Completed · Phase 2 · Interventional · 18 enrolled · Jazz Pharmaceuticals
  NCT02564952updated 2022-09-28
• Efficacy and Safety of Perampanel in Combination in Glioma-refractory Epilepsy
  Withdrawn · Interventional · 0 enrolled · Assistance Publique Hopitaux De Marseille
  NCT03636958updated 2022-06-27
• Use of Clobazam for Epilepsy and Anxiety
  Completed · Phase 4 · Interventional · 20 enrolled · Hugo W. Moser Research Institute at Kennedy Krieger, Inc.
  NCT03371836updated 2021-03-04
• Effects of Clobazam on Sleep and Daytime Function in Patients With Epilepsy
  Completed · Observational · 13 enrolled · Brigham and Women's Hospital
  NCT02911025updated 2021-02-08
• A Placebo-controlled Study of Efficacy & Safety of 2 Trough-ranges of Everolimus as Adjunctive Therapy in Patients With Tuberous Sclerosis Complex (TSC) & Refractory Partial-onset Seizures
  Completed · Phase 3 · Interventional · 366 enrolled · Novartis Pharmaceuticals
  NCT01713946updated 2018-11-07

CPIC-curated drug–gene pairs for Clobazam. Levels describe the strength of curated evidence and guideline status — never a recommendation to test or to adjust therapy.

• CYP2C19CPIC B/C (provisional)ClinPGx 2AFDA label: Actionable PGx

Frequently asked questions

How does Clobazam work?

The exact mechanism of action for clobazam, a 1,5-benzodiazepine, is not fully understood but is thought to involve potentiation of GABAergic neurotransmission resulting from binding at the benzodiazepine site of the GABA A receptor.

What is Clobazam used for?

According to FDA labeling, Clobazam carries indications including: Clobazam oral suspension is indicated for the adjunctive treatment of seizures associated with Lennox-Gastaut syndrome (LGS) in patients 2 years of age or older.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Clobazam?

Clobazam is classified as Benzodiazepine derivatives, Benzodiazepine, Cytochrome P450 2D6 Inhibitors, Cytochrome P450 3A4 Inducers, GABA A Modulators, Increased GABA Activity.

What are the brand names for Clobazam?

Clobazam is marketed under brand names including Onfi, Sympazan.

What are the contraindications for Clobazam?

Clobazam labeling lists contraindications including: Clobazam oral suspension is contraindicated in patients with a history of hypersensitivity to the drug or its ingredients. Hypersensitivity reactions have included serious dermatological reactions [see Warnings and Precautions ( 5.6 , 5.7 )].. Always consult the full prescribing information and a clinician.