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Understanding Medical Cannabis Formulations: A Primer for GPs
Published: August 2025
Australian general practitioners (GPs) who prescribe medical cannabis are faced with a diverse and rapidly evolving range of formulations to choose from. Beyond selecting a product with the appropriate cannabinoid profile for their patient's presentation, GPs must also consider the route of administration and formulation type, which could significantly impact onset, duration, tolerability, and patient adherence.1,2
This primer explores the key medical cannabis dosage forms currently available, their pharmacokinetic profiles, patient considerations, and practical prescribing tips to help guide formulation decisions.
Overview of medical cannabis formulations
The two primary active compounds in medical cannabis, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), are available as various dosage forms.1,3 Each has distinct benefits and limitations, depending on the therapeutic goal and patient-specific factors.1 The most commonly available forms include:
1. Oral formulations: oils, pastilles, capsules
Oral formulations, including oils, and softgel capsules, are the most commonly prescribed medical cannabis products in Australia.4 Oils typically come in bottles with graduated droppers, allowing for flexible dosing. Capsules and pastilles offer convenience and fixed doses.1
Pharmacokinetics:
Onset: 60 -180 minutes1
Peak effect: 2-4 hours5
Duration: 6-8 hours1Pros and Cons:
Pros Cons Discreet and convenient to administer1 Patients with dexterity challenges may find oils difficult to administer9 Suitable for chronic conditions requiring longer-lasting relief1,5 Delayed onset may limit use for acute symptom control1 Slower onset and lower peak concentrations may potentially reduce risk of intoxication6,7,8 Low bioavailability due to first pass metabolism5 Prescribing tips:
- Start with a low dose, titrate slowly (e.g. “start low and go slow”).1
- Oral absorption can be enhanced by administering in the presence of fats and oils thus ideally taken with food.1
2. Inhaled formulations: vaporised dried flower or inhalation oils
Medical cannabis can be inhaled via a medical vaporiser device which delivers vapour containing cannabinoids and terpenes to the lungs.9
Smoking is not an approved method for medical cannabis administration in Australia.5
Use of a registered medical vaporizer device reduces exposure to potentially toxic compounds of cannabis smoke and helps to reduce variability in the cannabinoid content delivered.9
Pharmacokinetics:
Onset: 5-10 minutes1
Peak effect: 15-30 minutes5
Duration: 2-4 hours1Pros and Cons:
Pros Cons Rapid onset may be useful for episodic or breakthrough symptoms1 Shorter duration of action than oral formulations with variable bioavailability7 Dose titration is patient-guided - patients stop when symptom relief is achieved (within daily THC limits)9 Not suitable for patients with respiratory disease (e.g. asthma, chronic obstructive pulmonary disease)2 Lack of first-pass metabolism may improve cannabinoid absorption6 May be associated with compliance issues10 Prescribing tips:
- Inhaled forms may be useful as an adjunct to oral formulations for conditions like chronic pain with breakthrough flares.1
- Ensure patients have access to a TGA-approved vaporiser (details: TGA website).5,6
3. Oromucosal sprays
These sprays are administered under the tongue or inside the cheek for mucosal absorption.10 Currently there is only one such product available in Australia (nabiximols THC 27mg: CBD 25mg oral spray), which is TGA-approved for spasticity in multiple sclerosis.12
Pharmacokinetics:
Onset: 15-45 minutes1
Peak effect: 1-2 hours10
Duration: 6-8 hours1Pros and Cons:
Pros Cons Faster onset than oral ingestion1 May cause local irritation (dry mouth, oral ulcers) 12 Suitable for patients with swallowing difficulties 8 Can be more expensive than other forms 1 Fixed metred dosing facilitates dose titration and may be easier to administer than some oral formulations 5 TGA-approved for patients with multiple sclerosis only.12 * *Patients may be able to access via Special Access or Authorised Prescriber scheme for other conditions
Prescribing tips:
- Consider oromucosal sprays when rapid symptom relief is needed but inhalation is contraindicated, such as in patients with respiratory disease.2,10
- Six to eight sprays of nabiximols are generally required for symptomatic relief with a daily limit of 12 sprays.11
4. Topical preparations
Topical formulations such as creams, ointments, or gels are suitable for localised symptoms such as dermatological conditions or arthritis pain.1 They exert their actions locally rather than systemically.1 THC is not well absorbed via the skin however CBD and the minor cannabinoid cannabinol (CBN) are much more permeable than THC.5
Pharmacokinetics:
Onset: 5-120 minutes13
Peak effect: variable 13
Duration: variable13Pros and Cons:
Pros Cons May be useful for localised pain or inflammation 13 Limited clinical evidence to support efficacy1 Low risk of intoxication or systemic side effects13 Local side effects such as contact dermatitis13 Steady delivery of active compounds over prolonged period13 Variable absorption through the skin barrier13 Administration tips:
- Topical preparations should not be applied to broken skin.14
- Advise patients not to rub the topical preparation into the skin vigorously.14
Factors to consider when choosing a formulation
1. Symptom profile and onset requirements
- Acute symptoms → inhaled or oromucosal.1
- Chronic conditions → oral formulations.1
- Mixed profiles → combination therapy.1
2. Patient preference and practicality
- Some prefer oils, capsules for discretion.
- Others prefer inhaled forms for feedback.
- Consider dexterity, cognition, access to devices.
3. Safety and contraindications
- Avoid inhaled in respiratory disease.2
- Avoid THC in pregnancy, unstable CV disease, psychiatric history.5
- Watch drug interactions with hepatic enzymes.5
4. Dosing control and titration
- Oral oils: flexible but delayed onset.1,10
- Capsules/pastilles/sprays: consistent dosing.1,13
- Inhaled: rapid but variable.1,8
Summary
Clinicians prescribing medical cannabis have a considerable array of dosage forms to choose from. Understanding the factors that influence formulation selection may be central to safer more effective patient care.1,2 Choosing the most appropriate dosage form may enhance therapeutic outcomes, minimise side effects, and improve adherence.1,2
By familiarising themselves with the available formats (oral, inhaled, oromucosal, topical) and considering patient-specific needs and preferences, GPs may be better positioned to deliver personalised and evidence-informed care in this emerging therapeutic area.
This article is intended for educational purposes and does not replace clinical judgment or regulatory requirements.
Disclaimer: Medical cannabis products may be associated with adverse events. For more information please contact medinfo@saged.com.au. Medical cannabis products are not suitable for use during pregnancy or breastfeeding, for anyone with a history with psychotic disorders, or for those with unstable cardiovascular disease. Treatment for patients under 18 years is recommended under the guidance of a paediatrician. Patients should not drive or operate machinery while being treated with some forms of medical cannabis.
Understanding Medical Cannabis Formulations: A Primer for GPs
Published: August 2025
Australian general practitioners (GPs) who prescribe medical cannabis are faced with a diverse and rapidly evolving range of formulations to choose from. Beyond selecting a product with the appropriate cannabinoid profile for their patient's presentation, GPs must also consider the route of administration and formulation type, which could significantly impact onset, duration, tolerability, and patient adherence.1,2
This primer explores the key medical cannabis dosage forms currently available, their pharmacokinetic profiles, patient considerations, and practical prescribing tips to help guide formulation decisions.
Overview of medical cannabis formulations
The two primary active compounds in medical cannabis, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), are available as various dosage forms.1,3 Each has distinct benefits and limitations, depending on the therapeutic goal and patient-specific factors.1 The most commonly available forms include:
1. Oral formulations: oils, pastilles, capsules
Oral formulations, including oils, and softgel capsules, are the most commonly prescribed medical cannabis products in Australia.4 Oils typically come in bottles with graduated droppers, allowing for flexible dosing. Capsules and pastilles offer convenience and fixed doses.1
Pharmacokinetics:
Onset: 60 -180 minutes1
Peak effect: 2-4 hours5
Duration: 6-8 hours1
Pros and Cons:
| Pros | Cons |
|---|---|
| Discreet and convenient to administer1 | Patients with dexterity challenges may find oils difficult to administer9 |
| Suitable for chronic conditions requiring longer-lasting relief1,5 | Delayed onset may limit use for acute symptom control1 |
| Slower onset and lower peak concentrations may potentially reduce risk of intoxication6,7,8 | Low bioavailability due to first pass metabolism5 |
Prescribing tips:
- Start with a low dose, titrate slowly (e.g. “start low and go slow”).1
- Oral absorption can be enhanced by administering in the presence of fats and oils thus ideally taken with food.1
2. Inhaled formulations: vaporised dried flower or inhalation oils
Medical cannabis can be inhaled via a medical vaporiser device which delivers vapour containing cannabinoids and terpenes to the lungs.9
Smoking is not an approved method for medical cannabis administration in Australia.5
Use of a registered medical vaporizer device reduces exposure to potentially toxic compounds of cannabis smoke and helps to reduce variability in the cannabinoid content delivered.9
Pharmacokinetics:
Onset: 5-10 minutes1
Peak effect: 15-30 minutes5
Duration: 2-4 hours1
Pros and Cons:
| Pros | Cons |
|---|---|
| Rapid onset may be useful for episodic or breakthrough symptoms1 | Shorter duration of action than oral formulations with variable bioavailability7 |
| Dose titration is patient-guided - patients stop when symptom relief is achieved (within daily THC limits)9 | Not suitable for patients with respiratory disease (e.g. asthma, chronic obstructive pulmonary disease)2 |
| Lack of first-pass metabolism may improve cannabinoid absorption6 | May be associated with compliance issues10 |
Prescribing tips:
- Inhaled forms may be useful as an adjunct to oral formulations for conditions like chronic pain with breakthrough flares.1
- Ensure patients have access to a TGA-approved vaporiser (details: TGA website).5,6
3. Oromucosal sprays
These sprays are administered under the tongue or inside the cheek for mucosal absorption.10 Currently there is only one such product available in Australia (nabiximols THC 27mg: CBD 25mg oral spray), which is TGA-approved for spasticity in multiple sclerosis.12
Pharmacokinetics:
Onset: 15-45 minutes1
Peak effect: 1-2 hours10
Duration: 6-8 hours1
Pros and Cons:
| Pros | Cons |
|---|---|
| Faster onset than oral ingestion1 | May cause local irritation (dry mouth, oral ulcers) 12 |
| Suitable for patients with swallowing difficulties 8 | Can be more expensive than other forms 1 |
| Fixed metred dosing facilitates dose titration and may be easier to administer than some oral formulations 5 | TGA-approved for patients with multiple sclerosis only.12 * |
*Patients may be able to access via Special Access or Authorised Prescriber scheme for other conditions
Prescribing tips:
- Consider oromucosal sprays when rapid symptom relief is needed but inhalation is contraindicated, such as in patients with respiratory disease.2,10
- Six to eight sprays of nabiximols are generally required for symptomatic relief with a daily limit of 12 sprays.11
4. Topical preparations
Topical formulations such as creams, ointments, or gels are suitable for localised symptoms such as dermatological conditions or arthritis pain.1 They exert their actions locally rather than systemically.1 THC is not well absorbed via the skin however CBD and the minor cannabinoid cannabinol (CBN) are much more permeable than THC.5
Pharmacokinetics:
Onset: 5-120 minutes13
Peak effect: variable 13
Duration: variable13
Pros and Cons:
| Pros | Cons |
|---|---|
| May be useful for localised pain or inflammation 13 | Limited clinical evidence to support efficacy1 |
| Low risk of intoxication or systemic side effects13 | Local side effects such as contact dermatitis13 |
| Steady delivery of active compounds over prolonged period13 | Variable absorption through the skin barrier13 |
Administration tips:
- Topical preparations should not be applied to broken skin.14
- Advise patients not to rub the topical preparation into the skin vigorously.14
Factors to consider when choosing a formulation
1. Symptom profile and onset requirements
- Acute symptoms → inhaled or oromucosal.1
- Chronic conditions → oral formulations.1
- Mixed profiles → combination therapy.1
2. Patient preference and practicality
- Some prefer oils, capsules for discretion.
- Others prefer inhaled forms for feedback.
- Consider dexterity, cognition, access to devices.
3. Safety and contraindications
- Avoid inhaled in respiratory disease.2
- Avoid THC in pregnancy, unstable CV disease, psychiatric history.5
- Watch drug interactions with hepatic enzymes.5
4. Dosing control and titration
- Oral oils: flexible but delayed onset.1,10
- Capsules/pastilles/sprays: consistent dosing.1,13
- Inhaled: rapid but variable.1,8
Summary
Clinicians prescribing medical cannabis have a considerable array of dosage forms to choose from. Understanding the factors that influence formulation selection may be central to safer more effective patient care.1,2 Choosing the most appropriate dosage form may enhance therapeutic outcomes, minimise side effects, and improve adherence.1,2
By familiarising themselves with the available formats (oral, inhaled, oromucosal, topical) and considering patient-specific needs and preferences, GPs may be better positioned to deliver personalised and evidence-informed care in this emerging therapeutic area.
This article is intended for educational purposes and does not replace clinical judgment or regulatory requirements.
Disclaimer: Medical cannabis products may be associated with adverse events. For more information please contact medinfo@saged.com.au. Medical cannabis products are not suitable for use during pregnancy or breastfeeding, for anyone with a history with psychotic disorders, or for those with unstable cardiovascular disease. Treatment for patients under 18 years is recommended under the guidance of a paediatrician. Patients should not drive or operate machinery while being treated with some forms of medical cannabis.