Clobazam structure.svg
Clobazam ball-and-stick model.png
Clinical data
Trade namesFrisium, Urbanol, Onfi, Tapclob
AHFS/Drugs.comMicromedex Detailed Consumer Information
License data
  • US: C (Risk not ruled out)
Routes of
Oral (tablets and Oral Suspension)
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailability87% (oral)
Protein binding80–90%
Elimination half-lifeclobazam: 36–42 hours, N-desmethylclobazam: 71–82h
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.040.810 Edit this at Wikidata
Chemical and physical data
Molar mass300.74 g·mol−1
3D model (JSmol)

Clobazam (marketed under the brand names Frisium, Urbanol, Onfi, and Tapclob ) is a benzodiazepine class medication that was patented in 1968[1] and has been marketed as an anxiolytic since 1975[2] and an anticonvulsant since 1984.[3]

Medical uses[edit]

Clobazam is used for epilepsy. It is unclear if there are any benefits to clobazam over other seizure medications for children with Rolandic epilepsy or other epileptic syndromes.[4][needs update]

As of 2005, clobazam is approved in Canada for add-on use in tonic-clonic, complex partial, and myoclonic seizures.[5] Clobazam is approved for adjunctive therapy in complex partial seizures[6] certain types of status epilepticus, specifically the mycolonic, myoclonic-absent, simple partial, complex partial, and tonic varieties,[7] and non-status absence seizures. It is also approved for treatment of anxiety.

In India, clobazam is approved for use as an adjunctive therapy in epilepsy and in acute and chronic anxiety.[8] In Japan, clobazam is approved for adjunctive therapy in treatment-resistant epilepsy featuring complex partial seizures.[9] In New Zealand, clobazam is marketed as Frisium[10] In the United Kingdom clobazam (Frisium) is approved for short-term (2–4 weeks) relief of acute anxiety in patients who have not responded to other drugs, with or without insomnia and without uncontrolled clinical depression.[11] It was not approved in the US until October 25, 2011, when it was approved for the adjunctive treatment of seizures associated with Lennox-Gastaut Syndrome in patients 2 years of age or older.[12]

It is also approved for adjunctive therapy for epilepsy in patients who have not responded to first-line drugs and in children who are refractory to first-line drugs. It is not recommended for use in children between the ages of six months and three years, unless there is a compelling need.[11] In addition to epilepsy and severe anxiety, clobazam is also approved as a short-term (2–4 weeks) adjunctive agent in schizophrenia and other psychotic disorders to manage anxiety or agitation.[11]

Clobazam is also available as an oral suspension in the UK, under the trade name of Tapclob.

Clobazam is sometimes used for refractory epilepsies. However, long-term prophylactic treatment of epilepsy has considerable drawbacks, most importantly loss of antiepileptic effects due to tolerance which may render long-term therapy ineffective.[13] Other antiepileptic drugs may therefore be preferred for the long-term management of epilepsy. Furthermore, benzodiazepines have the drawback, particularly after long-term use, of causing rebound seizures upon abrupt or over-rapid discontinuation of therapy forming part of the benzodiazepine withdrawal syndrome.


Clobazam should be used with great care in patients with the following disorders:

Benzodiazepines require special precaution if used in the elderly, during pregnancy, in children, alcohol or drug-dependent individuals and individuals with comorbid psychiatric disorders.[15]

Side effects[edit]


Common side effects include fever, lethargy or sleepiness, drooling, and constipation.[16]

Post Marketing Experience[edit]

Warnings and Precautions[edit]

In December 2013 the FDA added warnings to the label for clobazam, that it can cause serious skin reactions, Stevens–Johnson syndrome, and toxic epidermal necrolysis, especially in the first eight weeks of treatment.[17]

Drug interactions[edit]


Overdose and intoxication with benzodiazepines, including clobazam, may lead to CNS depression, associated with drowsiness, confusion, and lethargy, possibly progressing to ataxia, respiratory depression, hypotension, and coma or death. The risk of a fatal outcome is increased in cases of combined poisoning with other CNS depressants, including alcohol.[18]

Abuse potential and addiction[edit]

Clobazam in animal studies has been shown to increase reward seeking behaviours which may suggest an increased risk of addictive behavioural patterns.[19] Significant clobazam abuse has been reported in some countries, according to a 1983 World Health Organisation report.[20]

Dependence and withdrawal[edit]

In humans tolerance to the anticonvulsant effects of clobazam may occur[21] and withdrawal seizures can occur during abrupt or overrapid withdrawal.[22]

Clobazam as with other benzodiazepine drugs can lead to physical dependence, addiction, and what is known as the benzodiazepine withdrawal syndrome. Withdrawal from clobazam or other benzodiazepines after regular use often leads to withdrawal symptoms which are similar to those seen during alcohol and barbiturate withdrawal. The higher the dose and the longer the drug is taken, the greater the risk of experiencing unpleasant withdrawal symptoms. Withdrawal symptoms can, however, occur from standard dosages and also after short-term use[not specific enough to verify]. Benzodiazepine treatment should be discontinued as soon as possible via a slow and gradual dose reduction regimen.[23]


Clobazam is a GABAA receptor agonist and may affect sodium channels and voltage-sensitive calcium channels.[24]

Like other 1,5-benzodiazepines (For example, arfendazam, lofendazam, or CP-1414S), the active metabolite N-desmethyl-clobazam has less affinity for the α1 subunit of the GABAA receptor compared to the 1,4-benzodiazepines. It has higher affinity for α2 containing receptors, where it has positive modulatory activity.[25][26]

In a double-blind placebo-controlled trial published in 1990 comparing it to clonazepam, 10 mg of clobazam was shown to be less sedating than either 0.5 mg or 1 mg of clonazepam.[27]

The α1 subtype of the GABAA receptor, was shown to be responsible for the sedative effects of diazepam by McKernan et al. in 2000, who also showed that its anxiolytic and anticonvulsant properties could still be seen in mice whose α1 receptors were insensitive to diazepam.[28]

In 1996, Nakamura et al. reported that clobazam and its active metabolite, N-desmethylclobazam (norclobazam), work by enhancing GABA-activated chloride currents at GABAA-receptor-coupled Cl channels. It was also reported that these effects were inhibited by the GABA antagonist flumazenil, and that clobazam acts more efficiently in GABA-deficient brain tissue.[29]


Clobazam has two major metabolites: N-desmethyl-clobazam and 4-hydroxyclobazam, the former of which is active.[30] The demethylation is facilitated by CYP2C19, CYP3A4, and CYP2B6 and the 4-hydroxyclobazam by CYP2C18 and CYP2C19.[31]


Clobazam is a 1,5-benzodiazepine, meaning that its diazepine ring has nitrogen atoms at the 1 and 5 positions (instead of the usual 1 and 4).[32]

It is not soluble in water and is available in oral form only.[24][18]


Clobazam was discovered at the Maestretti Research Laboratories in Milan and was first published in 1969;[33] Maestretti was acquired by Roussel Uclaf[34] which became part of Sanofi.

See also[edit]


  1. ^ T3DB, "". "T3DB Clozabam". T3DB.
  2. ^ Freche, C (1975). "Study of an anxiolytic, clobazam, in otorhinolaryngology in psychosomatic pharyngeal manifestations". Semaine des Hôpitaux. Thérapeutique. 51 (4): 261–3. PMID 5777.
  3. ^ "Clobazam in Treatment of Refractory Epilepsy: The Canadian Experience. A Retrospecti". Epilepsia. 32 (3): 407–16. 1991. doi:10.1111/j.1528-1157.1991.tb04670.x. PMID 2044502.
  4. ^ Arya, R; Anand, V; Garg, SK; Michael, BD (Oct 4, 2014). "Clobazam monotherapy for partial-onset or generalized-onset seizures". The Cochrane Database of Systematic Reviews. 10 (10): CD009258. doi:10.1002/14651858.CD009258.pub2. PMID 25280512.
  5. ^ Epilepsy Ontario (2005). "Clobazam". Medications. Archived from the original on 2006-08-18. Retrieved 2006-03-04.
  6. ^ Larrieu, JL; Lagueny, A; Ferrer, X; Julien, J (1986). "Epilepsy with continuous discharges during slow-wave sleep. Treatment with clobazam". Revue d'Electroencephalographie et de Neurophysiologie Clinique. 16 (4): 383–94. doi:10.1016/S0370-4475(86)80028-4. PMID 3103177.
  7. ^ Gastaut, H; Tinuper, P; Aguglia, U; Lugaresi, E (1984). "Treatment of certain forms of status epilepticus by means of a single oral dose of clobazam". Revue d'Electroencephalographie et de Neurophysiologie Clinique. 14 (3): 203–6. doi:10.1016/S0370-4475(84)80005-2. PMID 6528075.
  8. ^ "Frisium Press Kit". Aventis Pharma India. Archived from the original on 2005-03-05. Retrieved 2006-08-02.
  9. ^ Shimizu, H; Kawasaki, J; Yuasa, S; Tarao, Y; Kumagai, S; Kanemoto, K (2003). "Use of clobazam for the treatment of refractory complex partial seizures". Seizure. 12 (5): 282–6. doi:10.1016/S1059-1311(02)00287-X. PMID 12810340.
  10. ^ Epilepsy New Zealand (2000). "Antiepileptic Medication". Archived from the original on 24 April 2005. Retrieved 11 July 2005.
  11. ^ a b c sanofi-aventis (2002). "Frisium Tablets 10 mg, Summary of Product Characteristics from eMC". electronic Medicines Compendium. Retrieved 11 July 2005.
  12. ^ "FDA Approves ONFI™ (clobazam) for the Adjunctive Treatment of Seizures Associated with Lennox-Gastaut Syndrome in Patients Two Years and Older" (Press release). Lundbeck. Retrieved 2011-10-25.
  13. ^ Isojärvi, JI; Tokola, RA (1998). "Benzodiazepines in the treatment of epilepsy in people with intellectual disability". Journal of Intellectual Disability Research. 42 (Suppl 1): 80–92. PMID 10030438.
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  16. ^ Clobazam label Last updated December 2014
  17. ^ FDA. December 3rd, 2013 FDA Drug Safety Podcast: FDA warns of serious skin reactions with the anti-seizure drug Onfi (clobazam) and has approved label changes
  18. ^ a b Fruchtengarten L Inchem - Clobazam. Created July 1997, Reviewed 1998.
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