Clobazam

For an informed discussion with your doctor or pharmacist. This information collection is not a clinically validated interaction checker. Missing data do not establish safety. Do not change or stop prescribed medicines on the basis of this information. The findings apply to the specific conditions studied; laboratory and animal studies cannot be directly extrapolated to humans.

Active substance: Clobazam

Examples of brand names: Frisium [DE]

ATC code: N05BA09

Main use (for orientation): Epilepsy; anxiety

Documented research summary

CBD mainly increases N-desmethylclobazam; controlled pharmacokinetics and repeated clinical observation support the finding. Sedation is more frequent; do not confuse this with an equally large increase in clobazam concentration.

Uncertainties and limitations

CBGA/clobazam only in mice; no clinical extrapolation.

Separately recorded findings

7 separately recorded findings. Each statement applies to its documented study context.

CBD – clinically studied

Finding ID: B0002

Type of result: Positive finding / indication

Observation: More somnolence/sedation; active metabolite decisive.

Mechanism: Pharmacokinetics/pharmacodynamics; sedating combination

Study type: Clinical studies evaluated by regulators

Context studied: Pharmaceutical CBD solution.

Clinical interpretation: High

Limitations and uncertainties: Assess metabolite and parent substance separately.

Original sources for this finding: Epidyolex: EPAR – Product Information [CL01]

CBD – clinically studied

Finding ID: B0008

Type of result: Positive finding / indication

Observation: N-desmethylclobazam AUC/Cmax approximately 3.4-fold; clobazam approximately 1.2-fold.

Mechanism: CYP2C19 inhibition

Study type: Open-label phase I pharmacokinetics

Context studied: n=12 in the pair arm; CBD 750 mg twice daily.

Clinical interpretation: High

Limitations and uncertainties: Healthy people.

Original sources for this finding: A Phase 1, Open-Label, Pharmacokinetic Trial to Investigate Possible Drug-Drug Interactions Between Clobazam, Stiripentol, or Valproate and Cannabidiol in Healthy Subjects [CL03]

CBD – clinically studied

Finding ID: B0009

Type of result: Positive finding / indication

Observation: Clobazam increased 7-OH-CBD: AUC 1.47-fold, Cmax 1.73-fold.

Mechanism: Bidirectional metabolic interaction

Study type: Open-label phase I pharmacokinetics

Context studied: CBD 750 mg twice daily; combination n=11.

Clinical interpretation: Possible; clinical metabolite contribution unclear

Limitations and uncertainties: Direction: medicine → CBD metabolite.

Original sources for this finding: A Phase 1, Open-Label, Pharmacokinetic Trial to Investigate Possible Drug-Drug Interactions Between Clobazam, Stiripentol, or Valproate and Cannabidiol in Healthy Subjects [CL03]

CBD – clinically studied

Finding ID: B0013

Type of result: Positive finding / indication

Observation: N-desmethylclobazam AUC 2.6-fold; Cmax 2.2-fold.

Mechanism: CYP2C19 inhibition

Study type: Double-blind randomised phase II pharmacokinetics

Context studied: 20 patients randomised (16 CBD, 4 placebo); primary evaluable pharmacokinetics 10 CBD/3 placebo. CBD 20 mg/kg/day, 10-day titration and 21-day maintenance; comparison day 33/day 1.

Clinical interpretation: High

Limitations and uncertainties: Small evaluable pharmacokinetic group (10 CBD/3 placebo); seven people excluded from pharmacokinetic analysis. Not an efficacy or long-term safety study.

Original sources for this finding: A Phase 2, Double-Blind, Placebo-Controlled Trial to Investigate Potential Drug-Drug Interactions Between Cannabidiol and Clobazam [CL04]

CBD – clinically studied

Finding ID: B0014

Type of result: No / minor effect under the conditions studied

Observation: Clobazam AUC geometric mean ratio 1.1; Cmax ratio 1.0.

Mechanism: Parent-substance pharmacokinetics

Study type: Double-blind randomised phase II pharmacokinetics

Context studied: Same sample as B0013; primary evaluable pharmacokinetics 10 CBD/3 placebo, not all 20 randomised patients.

Clinical interpretation: No relevant parent-substance signal

Limitations and uncertainties: No assurance of safety: active metabolite increases.

Original sources for this finding: A Phase 2, Double-Blind, Placebo-Controlled Trial to Investigate Potential Drug-Drug Interactions Between Cannabidiol and Clobazam [CL04]

CBD – clinical signals

Finding ID: B0051

Type of result: Positive finding / indication

Observation: Clobazam/N-desmethylclobazam ↑; p=<0.0001.

Mechanism: Mechanism uncertain

Study type: Observational study

Context studied: n=59; total.

Clinical interpretation: Clinical significance unclear

Limitations and uncertainties: Association; CL20 context/limitations.

Original sources for this finding: Final analysis of potential drug-drug interactions between highly purified cannabidiol and anti-seizure medications in an open-label expanded access program [CL20]

CBD – clinical signals

Finding ID: B0079

Type of result: Positive finding / indication

Observation: Mean norclobazam concentration +500% after 4 weeks; adverse effects decreased after clobazam reduction.

Mechanism: Metabolic inhibition plausible

Study type: Case series

Context studied: n=13; pharmaceutical CBD in refractory epilepsy.

Clinical interpretation: High

Limitations and uncertainties: Not an AUC measurement: do not present the concentration increase as AUC.

Original sources for this finding: Drug-drug interaction between clobazam and cannabidiol in children with refractory epilepsy [CL22]

References and access status

[CA_L_D0039] CLOBAZAM (CLOBAZAM) TABLET [MICRO LABS LIMITED]

Original source / bibliographic reference

Authors: Micro Labs Limited

Year: 2026

Source type: Current published human-use SPL / product information

Source access – 23 October 2026: Source destination was accessible when checked.

Bibliographic attribution or source identity cross-checked.

[CL01] Epidyolex: EPAR – Product Information

Original source / bibliographic reference

Authors: European Medicines Agency / marketing authorisation holder

Year: 2026

Source type: Regulatory product information

Source access – 23 October 2026: Source destination was accessible when checked.

Bibliographic attribution or source identity cross-checked.

[CL03] A Phase 1, Open-Label, Pharmacokinetic Trial to Investigate Possible Drug-Drug Interactions Between Clobazam, Stiripentol, or Valproate and Cannabidiol in Healthy Subjects

Original source / bibliographic reference

Authors: Morrison G; Crockett J; Blakey G; Sommerville K

Year: 2019

Source type: Open-label phase I study with a fixed sequence

DOI: 10.1002/cpdd.665

PMID: 30791225

Source access – 23 October 2026: Direct retrieval could not be fully verified; availability remains unresolved.

Bibliographic attribution or source identity cross-checked.

DOI – publisher access (access restrictions may apply)

PubMed Central – full-text access according to the literature database – Archive attribution confirmed by Europe PMC metadata. Direct retrieval was not fully verified here; access may require a browser check.

Europe PMC – full-text access according to the literature database – Listed as freely available HTML full text in the official Europe PMC metadata. Direct retrieval was not fully verified here.

[CL04] A Phase 2, Double-Blind, Placebo-Controlled Trial to Investigate Potential Drug-Drug Interactions Between Cannabidiol and Clobazam

Original source / bibliographic reference

Authors: VanLandingham KE; Crockett J; Taylor L; Morrison G

Year: 2020

Source type: Randomised double-blind phase II study

DOI: 10.1002/jcph.1634

PMID: 32652616

Source access – 23 October 2026: Direct retrieval could not be fully verified; availability remains unresolved.

Bibliographic attribution or source identity cross-checked.

DOI – publisher access (access restrictions may apply)

PubMed Central – full-text access according to the literature database – Archive attribution confirmed by Europe PMC metadata. Direct retrieval was not fully verified here; access may require a browser check.

Europe PMC – full-text access according to the literature database – Listed as freely available HTML full text in the official Europe PMC metadata. Direct retrieval was not fully verified here.

[CL20] Final analysis of potential drug-drug interactions between highly purified cannabidiol and anti-seizure medications in an open-label expanded access program

Original source / bibliographic reference

Authors: Gaston TE; Bebin EM; Cutter GR; Grayson L; Szaflarski JP

Year: 2023

Source type: Open-label longitudinal observational study

DOI: 10.1002/epi4.12815

PMID: 37593907

Source access – 23 October 2026: Automated direct retrieval was restricted; this does not establish that the link is broken.

Bibliographic attribution or source identity cross-checked.

PubMed – bibliographic reference / abstract

DOI – publisher access (access restrictions may apply)

Europe PMC – full-text access according to the literature database – Listed as freely available HTML full text in the official Europe PMC metadata. Direct retrieval was not fully verified here.

[CL22] Drug-drug interaction between clobazam and cannabidiol in children with refractory epilepsy

Original source / bibliographic reference

Authors: Geffrey AL; Pollack SF; Bruno PL; Thiele EA

Year: 2015

Source type: Clinical case series / expanded access

DOI: 10.1111/epi.13060

PMID: 26114620

Source access – 23 October 2026: Source destination was accessible when checked.

Bibliographic attribution or source identity cross-checked.

DOI – publisher access (access restrictions may apply)

[CA_P_39985501] Pharmacokinetic variability and use of therapeutic drug monitoring of cannabidiol in patients with refractory epilepsy.

Original source / bibliographic reference

Authors: Johannessen Landmark C, Sætre J, Gottås A, Wolden M, McQuade TA, Kjeldsen SF, Våtevik A, Sætre E, Svendsen T, Burns ML, Øiestad EL, Johannessen SI.

Year: 2025

Source type: Journal Article

DOI: 10.1111/epi.18284

PMID: 39985501

Source access – 23 October 2026: Source destination was accessible when checked.

Bibliographic attribution or source identity cross-checked.

DOI – publisher access (access restrictions may apply)

[CA_P_32969022] Cannabidiol in conjunction with clobazam: analysis of four randomized controlled trials.

Original source / bibliographic reference

Authors: Gunning B, Mazurkiewicz-Bełdzińska M, Chin RFM, Bhathal H, Nortvedt C, Dunayevich E, Checketts D.

Year: 2021

Source type: Meta-Analysis; research-article; Journal Article

DOI: 10.1111/ane.13351

PMID: 32969022

Source access – 23 October 2026: Source destination was accessible when checked.

Bibliographic attribution or source identity cross-checked.

DOI – publisher access (access restrictions may apply)

[CA_P_34384142] Cannabigerolic acid, a major biosynthetic precursor molecule in cannabis, exhibits divergent effects on seizures in mouse models of epilepsy.

Original source / bibliographic reference

Authors: Anderson LL, Heblinski M, Absalom NL, Hawkins NA, Bowen MT, Benson MJ, Zhang F, Bahceci D, Doohan PT, Chebib M, McGregor IS, Kearney JA, Arnold JC.

Year: 2021

Source type: Research Support, Non-U.S. Gov't; research-article; Journal Article; Research Support, N.I.H., Extramural

DOI: 10.1111/bph.15661

PMID: 34384142

Source access – 23 October 2026: Source destination was accessible when checked.

Bibliographic attribution or source identity cross-checked.

DOI – publisher access (access restrictions may apply)

Research as of 23 October 2026. Not all original full texts could be reviewed in full. Source accessibility and the strength of scientific evidence must be assessed separately. An accessible link does not establish medical approval; a bibliographic record with an abstract does not replace the original full text.

Drug search and explanation of the evidence · Guide: cannabinoids and medicines · Author and responsibility