Cannabidiol
Antiseizure medicines
Antiseizure medicines
A purified, non-intoxicating compound from the cannabis plant, given as an oral solution for rare severe childhood epilepsies.
Also called: CBD
Quick facts
- Group
- Antiseizure medicines
- Target
- Several possible targets (antiseizure mechanism not established)
- Used for
- Seizures of Lennox-Gastaut syndrome
- Key effects
- Diarrhoea · Sleepiness and tiredness
- Monitor
- Liver enzymes and bilirubin before · Drowsiness
- ATC
- N03AX24
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows cannabidiol bound to the human sodium channel Nav1.7, one of its many proposed targets; how it reduces seizures is still unknown.
Cannabidiol (CBD) is a phytocannabinoid without the psychoactive effect of THC and with little affinity for the CB1 and CB2 receptors. How it reduces seizures is unknown. Proposed actions include activating TRPV1, blocking the orphan receptor GPR55, activating 5-HT1A receptors and inhibiting adenosine reuptake (ENT-1), which together could lower neuronal excitability.
- CBD acts on several non-cannabinoid targets
- Neuronal excitability falls by an unclear route
- Fewer seizures in Dravet, Lennox-Gastaut and TSC
Indications
- Seizures of Lennox-Gastaut syndrome Epilepsy and seizures →
- Seizures of Dravet syndrome Epilepsy and seizures →
- Seizures of tuberous sclerosis complex Tuberous sclerosis complex →
Adverse effects
Common
- Diarrhoea
- Sleepiness and tiredness
- Loss of appetite and weight loss
- Trouble sleeping
- Drooling and problems with walking
Contraindications
- Allergy to cannabidiol or to any component of the solution
Key interactions
- Clobazam
- CBD raises the active metabolite of clobazam (N-desmethylclobazam): more sedation
- Valproate
- Higher risk of raised liver enzymes
- St John's wort and caffeine supplements
- May interact with CBD; they are reviewed before starting
- Alcohol
- Worse drowsiness
What is monitored
- Liver enzymes and bilirubin before and during treatment
- Weight and appetite
- Drowsiness, especially with clobazam
- Mood and suicidal thoughts
Administration and safety
- Oral solution measured with the oral syringe supplied; a dry syringe is used each time
- Given the same way each time with respect to food
- Can be given through a feeding tube
- Raised gradually and never stopped suddenly
Pregnancy and breastfeeding
There is little information in pregnancy; it is a decision for the treating team.
Nursing care
- Check liver tests before starting and during follow-up
- Watch for jaundice, dark urine and abdominal pain
- Weigh the child at visits
- Teach the family that pharmaceutical CBD is not the same as unregulated cannabis products
Pharmacokinetics
- Absorption
- Oral solution; poorly soluble in water, and a high-fat meal raises absorption
- Distribution
- Very lipophilic; stored in brain and fat, which prolongs its elimination
- Metabolism
- In the liver and gut by several CYPs; it also inhibits CYP2C and CYP3A4
Test yourself
Think of the answer, then tap the question to see it.
Which three conditions is pharmaceutical cannabidiol approved for?
Seizures of Lennox-Gastaut syndrome, Dravet syndrome and tuberous sclerosis complex.
Why can cannabidiol increase sedation when given with clobazam?
It raises levels of clobazam's active metabolite, N-desmethylclobazam.
Which laboratory tests are followed during cannabidiol treatment?
Liver tests (transaminases and bilirubin).
Connections
← Back to the class: Antiseizure medicines
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Cannabidiol: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); RCSB PDB - 8G1A: Cryo-EM structure of Nav1.7 with CBD (RCSB Protein Data Bank, 2026).
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Representative model, for educational purposes only.