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Public & PrescriberLast reviewed: April 2026

Cannabinoid Pharmacology: CBD, THC and CBD:THC

Teach molecule-level pharmacology while avoiding overclaiming.

Learning Objectives

Understand that CBD and THC are clinically different
Understand THC psychoactive, psychiatric, cognitive, driving and dependence risks
Understand CBD is non-intoxicating but pharmacologically active
Understand CBD CYP/UGT interaction relevance
Understand that route and formulation change exposure
Understand that evidence cannot be extrapolated between routes

Core Content

Cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) are the two most studied cannabinoids, but they have fundamentally different pharmacological profiles.

THC is psychoactive and carries psychiatric, cognitive, driving and dependence risks. CBD is non-intoxicating but remains pharmacologically active with significant drug interaction potential.

This distinction is critical for patient selection, safety monitoring, and regulatory classification.

Key Takeaways

  • 1CBD and THC are pharmacologically distinct molecules
  • 2THC carries psychoactive, psychiatric and dependence risks
  • 3CBD is non-intoxicating but has significant interaction potential
  • 4Evidence cannot be extrapolated between routes of administration
  • 5Formulation affects bioavailability and clinical outcomes

Case Example

A patient asks whether CBD oil from a health shop is the same as prescribed CBD. How should this be addressed?

Consumer CBD products are not medicines and are not regulated to pharmaceutical standards.

Pharmaceutical CBD (e.g., Epidyolex) has defined purity, dosing, and quality control.

The route, formulation, and dose of CBD affect its pharmacological profile.

Patients should not self-medicate with consumer products as a substitute for prescribed medicines.

Knowledge Check

Q1. Which statement about CBD is most accurate?

Q2. Can topical CBD evidence be used to support oral CBD prescribing?

Downloadable Tools

CBD vs THC comparison card

Side-by-side comparison of CBD and THC pharmacology

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Route/formulation evidence card

Quick reference for route-specific evidence boundaries

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Psychiatric THC caution card

Red-flag checklist for THC psychiatric risks

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Tools are provided as templates for clinical practice. Adapt to your clinic's specific requirements.

References

  1. [1]Devinsky O, et al. Cannabidiol: pharmacology and potential therapeutic role. Epilepsia. 2014;55(6):791-802.
  2. [2]Millar SA, et al. A systematic review on the pharmacokinetics of cannabidiol in humans. Front Pharmacol. 2018;9:1365.
  3. [3]Epidyolex SmPC. GW Pharmaceuticals. EMA.
  4. [4]Sativex SmPC. GW Pharmaceuticals.
Module 1: UK RegulatoryModule 3: Evidence Matrix

This material is educational and non-promotional. It does not constitute medical advice, prescribing advice, or a recommendation to use any medicine. Any use of an unlicensed medicine requires patient-specific clinical justification, informed consent, monitoring, pharmacovigilance and compliance with applicable regulatory requirements.