Medicinal cannabis in epilepsy – Jeremy Freeman | PAC 2024

From media-driven momentum to mainstream medicine: the story, science and funding of cannabidiol in paediatric epilepsy. 

Speaker biography:

Dr Jeremy Freeman received his medical degree from the University of Melbourne in 1994 and trained in general paediatrics, neurology and epilepsy at the Royal Children's Hospital from 1996-2003.

He then completed a two-year fellowship in clinical paediatric neurology at Northwestern University and Children's Memorial Hospital in Chicago, before returning to the RCH in 2005.

Jeremy has clinical research interests in epilepsy, EEG and neuroimaging. He received an American Epilepsy Society award for his work with the hypothalamic hamartoma epilepsy syndrome.

Insights:

(Powered by OpenAI)

Professor Jeremy Freeman traces the evolution of medicinal cannabidiol (CBD) for paediatric epilepsy in Australia, from anecdote-driven public pressure to evidence-based clinical practice. He recounts how early media stories—most notably the case of Charlotte Figi with Dravet syndrome—galvanised families and policymakers, leading to rapid legislative reform and compassionate access schemes despite limited initial evidence. Since then, high-quality randomised controlled trials have demonstrated that purified CBD (Epidiolex) provides a modest but clinically meaningful reduction in seizure frequency for specific refractory epilepsies, including Dravet syndrome, Lennox-Gastaut syndrome, and tuberous sclerosis complex. CBD is now an established adjunctive therapy, comparable in efficacy to other anti-seizure medications rather than a transformative cure.

Freeman emphasises that while CBD is generally well tolerated, its use requires careful clinical oversight, particularly due to significant drug–drug interactions (notably with clobazam, valproate, and mTOR inhibitors) and the need for liver function monitoring. He cautions against extrapolating evidence to THC-containing or “full-spectrum” cannabis products, for which there is no supportive data in epilepsy, despite widespread availability and marketing. With PBS funding now in place for selected indications, and variable state-based access for off-label use, CBD has moved from novelty to routine practice. The challenge for clinicians is no longer whether CBD works, but how to use it judiciously, safely, and equitably within the broader management of refractory paediatric epilepsy.

Key Insights

• Anecdote drove policy, not evidence: Public pressure following high-profile case stories (e.g. Charlotte’s Web) accelerated legislative reform long before robust trial data existed.
• CBD ≠ cannabis: Only purified cannabidiol has evidence for seizure reduction; THC and “full-spectrum” products remain unsupported by data.
• Evidence base is now solid — but narrow: Randomised trials demonstrate moderate efficacy and acceptable safety in Dravet syndrome, Lennox-Gastaut syndrome, and tuberous sclerosis complex, comparable to other add-on anti-seizure medications.
• Mechanism remains unclear: CBD has proven clinical benefit despite limited understanding of how it works.
• Drug interactions are clinically significant: CBD markedly increases norclobazam levels and interacts with valproate and mTOR inhibitors, necessitating monitoring.
• Adverse effects are common but manageable: Sedation, GI effects, and LFT abnormalities occur but rarely require cessation.
• Funding shapes access more than indication: PBS listing now supports use in Dravet and LGS, while off-label access depends on state schemes or self-funding.
• The hype has settled: CBD is no longer novel or “miraculous” — it is now another tool for refractory epilepsy.
  
  

Practical Recommendations for Acute Care Clinicians

• Be precise with language: Distinguish clearly between purified cannabidiol and non-evidence-based cannabis products when counselling families.
• Set realistic expectations: Present CBD as a moderately effective adjunct, not a cure or first-line therapy.
• Anticipate drug interactions: Check clobazam, valproate, and mTOR inhibitor co-prescription and monitor LFTs proactively.
• Expect sedation in acute settings: Increased somnolence may complicate assessment, especially in children on clobazam.
• Avoid THC-containing products: There is no evidence for seizure benefit and potential for harm.
• Understand local access pathways: Know your state’s compassionate access scheme and PBS eligibility to guide families accurately.
• Prepare for cost conversations: Families may arrive having price-compared unapproved products; clear, evidence-based guidance is essential.
• Normalise CBD’s role: Treat it like any other anti-seizure medication — useful, imperfect, and best used within a structured plan.