Prescribing medicinal cannabis

Abstract

The Australian Federal Government legalised access to medicinal cannabis in 2016. More than 100 different cannabis products are now available to prescribe. Most are oral preparations (oils) or capsules containing delta-9-tetrahydrocannabinol or cannabidiol. Driedflower products are also available. As most products are unregistered drugs, prescribing requires approval under the Therapeutic Goods Administration Special Access Scheme-B or Authorised Prescriber Scheme. Special Access Scheme Category B applications can be made online, with approval usually being given within 24-48 hours. However, supply chain problems may delay dispensing by the pharmacy. By the end of 2019, over 28,000 prescribing approvals had been issued to patients, involving more than 1400 doctors, mostly GPs. More than 70,000 approvals are projected by the end of 2020. Most prescriptions are for chronic non-cancer pain, anxiety, cancer-related symptoms, epilepsy and other neurological disorders. However, the evidence supporting some indications is limited. Many doctors are cautious about prescribing cannabis. While serious adverse events are rare, there are legitimate concerns around driving, cognitive impairment and drug dependence with products containing delta-9-tetrahydrocannabinol. Cannabidiol-only products pose fewer risks. What is medicinal cannabis? The cannabis plant contains hundreds of bioactive molecules, most of which are as yet uncharacterised. The two best studied cannabinoids are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is responsible for the intoxicating effects of cannabis due to its action on CB1 cannabinoid receptors. 6 Despite intoxicating effects at higher doses, clinical trial evidence generally supports the efficacy of THC in treating conditions such as chronic pain, spasticity in multiple sclerosis, anorexia and cachexia, Tourette syndrome and chemotherapyinduced nausea and vomiting. 7,8 Trials currently underway will help to better define the role of THC as a therapeutic across these and other conditions. 9,10 CBD has a very wide range of pharmacological actions but no intoxicating effects. Early evidence suggests therapeutic actions of CBD at relatively high doses (300-1500 mg) in treating epilepsy, anxiety and psychosis. 11-13 Numerous clinical trials are underway for other conditions such as neuropathic pain, drug and alcohol dependence and neurodegenerative disorders. In many countries, CBD is readily available in over-thecounter nutraceutical 'wellness' products. These contain very low doses (e.g. 5-25 mg) for which there is little current evidence of health benefits. Over-the-counter access to CBD is not yet available in Australia, although Jonathon C Arnold Deputy academic director, Lambert Initiative for Cannabinoid Therapeutics, Brain and Mind Centre 1

Medicinal cannabis use in palliative care

“…Most currently available medicinal cannabis products in Australia contain THC, CBD or both. 1 Clinicians remain uncertain as to which of the more than 400 compounds within the cannabis plant are most effective for individual symptoms, as well as which is the best product or combinations of the various cannabinoids, route of administration or dosing schedule. 6,7 There are also concerns about interaction with other medicines and long-term safety profiles.…”

“…THERE HAS BEEN INCREASING INTEREST in the use of medicinal cannabis over recent years and strong public pressure for its legalisation. 1 Recent legislative change in several Australian states has provided pathways for the use of medicinal cannabis for a range of indications including chronic pain, epilepsy, spasticity associated with multiple sclerosis, chemotherapy-induced nausea and vomiting, and the symptoms associated with terminal illness. 1,2 Despite overwhelming public belief in its value, the evidence supporting the use of cannabis in palliative care is limited.…”

“…3 Although the number of prescriptions of medicinal cannabis supplied by medical practitioners is increasing sharply, most of the 'medicinal cannabis' used by the general population is 'community acquired' (ie provided by unregistered suppliers), with only a small proportion obtained through legal pathways. 1 The exact constitution of these products is often unknown and variable. 4…”

“Is medical cannabis safe for my patients?” A practical review of cannabis safety considerations

“…The use of cannabis for medical purposes is increasing worldwide [5,32]. With the changing public and political opinion, more countries are implementing medical cannabis legalization.…”

Letter to the Editor: More prescribing resources for medicinal cannabis

“…We commend the authors for their informative article on prescribing medicinal cannabis in this rapidly evolving therapeutic area. 1 In 2019, given the absence of information on medicinal cannabis in usual reference texts such as the Australian Medicines Handbook, the NSW Therapeutic Advisory Group (NSW TAG) identified a resource gap for NSW public hospital clinicians. In collaboration with the NSW Cannabis Medicines Advisory Service, NSW TAG developed an information primer for Cannabis Medicines Use in Hospitals .…”