Cannabis has many active chemical constituents and two of these constituents, tetrahydrocannabinol (THC) and cannabidiol (CBD) have been investigated the most in respect of their medicinal value. THC is the major psychoactive constituent of cannabis and is considered responsible for giving so called “highs” to users of cannabis. CBD on the other hand, is not psychoactive. “Pure CBD” is not a controlled drug for the purposes of the 1971 Misuse of Drugs Act.

Products falling within Schedule 2 will contain varying quantities and ratios of THC and CBD and may be available in a range of pharmaceutical forms.

Currently there is no good evidence that products that contain THC are either safe or efficacious and there is a concern about the effect of THC on the developing brain. There is evidence that chronic high exposure to THC during recreational cannabis use can affect brain development, structure, and mental health.

Initial prescription of cannabis-based medicinal products must be made by a specialist. Subsequent prescriptions may be issued by another prescriber as part of a shared care agreement

Dronabinol: not available as a licensed medicine in the UK.

Private prescriptions from outside the UK will not be permissible as the law indicates that prescribing of cannabis-based products for medicinal use is restricted to only those clinicians listed on the Specialist Register of the General Medical Council.

Three conditions which can be treated with cannabinoids: 

Intractable chemotherapy-induced nausea and vomiting (Nabilone)

Nabilone can be prescribed by a specialist as an add-on treatment for adults 18 years and over with chemotherapy-induced nausea and vomiting which persists with optimised conventional antiemetics.

Dose: Initially 1 mg twice daily, increased if necessary to 2 mg twice daily throughout each cycle of cytotoxic therapy and, if necessary, for 48 hours after the last dose of each cycle, the first dose should be taken the night before initiation of cytotoxic treatment and the second dose 1–3 hours before the first dose of cytotoxic drug, daily dose maximum should be given in 3 divided doses; maximum 6 mg per day.

https://bnf.nice.org.uk/drug/nabilone.html

Severe treatment resistant epilepsy (Epidyolex)

Cannabidiol oral solution, Epidyolex (pure CBD oil) in conjunction with clobazam can be prescribed by specialists as an option for treating seizures associated with Lennox–Gastaut syndrome in people aged 2 years and older, only if the frequency of drop seizures is checked every 6 months, and cannabidiol is stopped if the frequency has not fallen by at least 30% compared with the 6 months before starting treatment.

Seizures associated with Lennox-Gastaut syndrome (in conjunction with clobazam) Adult: Initially 2.5 mg/kg twice daily for 1 week, then increased to 5 mg/kg twice daily, then increased in steps of 2.5 mg/kg twice daily, adjusted according to response, dose to be increased at weekly intervals, food may affect absorption (take at the same time with respect to food); maximum 20 mg/kg per day.

Seizures associated with Dravet syndrome (in conjunction with clobazam) Adult: Initially 2.5 mg/kg twice daily for 1 week, then increased to 5 mg/kg twice daily, then increased in steps of 2.5 mg/kg twice daily, adjusted according to response, dose to be increased at weekly intervals, food may affect absorption (take at the same time with respect to food); maximum 20 mg/kg per day.

From 1 October 2019, Epidyolex® has been classified as a Schedule 2 controlled drug (CD) in the UK rather than being exempt from scheduling (an ‘Exempt Product’) due to trace levels of THC in the medicine. Prior to licensing, Epidyolex® was available through compassionate use and extended access programmes. These are now closed to new patients.

https://bnf.nice.org.uk/drug/cannabidiol.html

Untreatable mild to moderate spasticity in Multiple Sclerosis patients (Sativex)

Specialists can ffer a 4-week trial of THC:CBD spray (Sativex) to treat moderate to severe spasticity in adults with multiple sclerosis, if other pharmacological treatments for spasticity are not effective. 

The spray container should be shaken before use and the spray should be directed at different sites on the oromucosal surface changing the application site each time the product is used. Patients should be advised that it might take up to 2 weeks to find the optimal dose and that undesirable effects can occur during this time, most commonly dizziness. These undesirable effects are usually mild and resolve in a few days. However, physicians should consider maintaining the current dose, reducing the dose or interrupting, at least temporarily, the treatment depending on seriousness and intensity. 

A titration period is required to reach optimal dose. The number and timing of sprays will vary between patients.

The number of sprays should be increased each day following the pattern given in the table below. The afternoon/evening dose should be taken at any time between 4 pm and bedtime. When the morning dose is introduced, it should be taken at any time between waking and midday. The patient may continue to gradually increase the dose by 1 spray per day, up to a maximum of 12 sprays per day, until they achieve optimum symptom relief. There should be at least a 15 minute gap between sprays.

Following the titration period, patients are advised to maintain the optimum dose achieved. The median dose in clinical trials for patients with multiple sclerosis is eight sprays per day. Once the optimum dose has been achieved, patients may spread the doses throughout the day according to individual response and tolerability. Re-titration upwards or downwards may be appropriate if there are any changes in the severity of the patient's condition, changes in their concomitant medication or if troublesome adverse reactions develop. Doses of greater than 12 sprays per day are not recommended.

If a clinically significant improvement in spasticity related symptoms is not seen during this initial 4 week trial of therapy, then treatment should be stopped. In the clinical trials this was defined as at least a 20% improvement in spasticity related symptoms on a 0-10 patient reported numeric rating scale (see section 5.1). The value of long term treatment should be re-evaluated periodically.

Chronic Pain

Do not offer CBD to manage chronic pain in adults (including MS) unless as part of a clinical trial.

Adults who started cannabis-based medicinal products to manage chronic pain in the NHS before this guidance was published (November 2019) should be able to continue treatment until they and their NHS clinician think it appropriate to stop.

Prescribing

Initial prescription of cannabis-based medicinal products must be made by a specialist medical practitioner (a doctor included in the register of specialist medical practitioners (the Specialist Register²). They should also have a special interest in the condition being treated³. For children and young people under the care of paediatric services, the initiating prescriber should also be a tertiary paediatric specialist.

After the initial prescription, subsequent prescriptions may be issued by another prescriber as part of a shared care¹ agreement under the direction of the initiating specialist prescriber, if:

• shared care is appropriate and in the person's best interest
• the person's clinical condition is stable
• the other prescriber is confident to make a fully informed prescribing decision about cannabis-based medicinal products.

Efficacy and safety of cannabis-based medicinal products should be monitored and evaluated, and doses should be adjusted by the initiating specialist prescriber as part of the shared care agreement.

Shared Care agreement

A shared care agreement for a person prescribed a cannabis-based medicinal product should include:

• the responsibilities of all parties (the initiating specialist prescriber, the other prescriber(s), the patient, family and/or carers)
• the nature and frequency of monitoring and how this will be reported
• when treatment might be stopped, for example, if it is not effective
• how suspected or known adverse reactions will be managed
• how communication will be managed between the initiating specialist prescriber, the other prescriber, the patient, family and/or carers
• how the treatment will be funded
• how care will be maintained when the patient, initiating specialist prescriber or other prescriber moves location (including transition to adult services).

Considerations

When prescribing and monitoring cannabis-based medicinal products, take into account:

• current and past use of cannabis (including any over-the-counter and online products)
• history of substance misuse including the illicit use of cannabis
• potential for dependence, diversion and misuse (in particular with THC)
• mental health and medical history, in particular, liver impairment, renal impairment, cardiovascular disease
• potential for interaction with other medicines, for example, central nervous system depressants and other centrally active drugs, antiepileptics and hormonal contraceptives
• pregnancy and breastfeeding⁴.

When prescribing cannabis-based medicinal products for babies, children and young people, pay particular attention to the:

• potential impact on psychological, emotional and cognitive development
• potential impact of sedation
• potential impact on structural and functional brain development.

When prescribing cannabis-based medicinal products, advise people to stop any non-prescribed cannabis, including over-the-counter, online and illicit products.

Prescribers should record details of treatment, clinical outcomes and adverse effects for people prescribed cannabis-based medicinal products, using local or national registers if available.

Further support

All UK healthcare professionals are able to access training through the Health Education England learning platform, e-learning for health: https://www.e-lfh.org.uk/programmes/cannabis-based-products-for-medicinal-use/ The e-learning module includes information on the pharmacology of cannabis, legislation governing medical use, therapeutic areas and the evidence available to support the prescription of a CBPM. It will be updated as more information becomes available.

 Frequently asked questions on the NHS England website to support prescribers: https://www.england.nhs.uk/medicines-2/support-for-prescribers/cannabis-based-products-for-medicinal-use/cannabis-based-products-for-medicinal-use-frequently-asked-questions/