Therapeutic Uses of Cannabis

British Medical Association

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000159653
• Edition: 1
• Topic: Medicine
• Subtopic: Medical Theory, Practice & Reference

At the last Annual Representative Meeting of the British Medical Association a motion was passed that `certain additional cannabinoids should be legalized for wider medicinal use.'' This report supports this landmark statement by reviewing the scientific evidence for the therapeutic use of cannabinoids and sets the agenda for change. It will be welcomed by those who believe that cannabinoids can be used in medical treatment. The report discusses in a clear and readable form the use and adverse effects of the drug for nausea, multiple sclerosis, pain, epilepsy, glaucoma, and asthma.

1
Introduction

The British Medical Association (BMA) is the professional organisation representing the medical professional in the UK. It was established in 1832 ‘to promote the medical and allied sciences, and to maintain the honour and interests of the profession’. The Board of Science and Education, a standing committee of the Association, supports this aim by acting as an interface between the profession, the government and the public. Its main role is to analyse and review critically issues of interest to the medical profession and the public and to contribute to the improvement of public health. Through this work the BMA has developed policies on a wide range of health issues, such as alcohol, smoking, infectious diseases, complementary medicine, pesticides, and transport safety.

In 1994 the BMA’s Annual Representative Meeting (ARM) adopted a resolution, requesting that the Board of Science and Education:

 

i) Prepare an authoritative statement on the relative risks of drugs of addiction including the principal controlled drugs, tobacco and alcohol;

ii) Advise on the role of the medical profession in relation to:

a) drug misusers who wish to discontinue their habit;

b) drug misusers who wish to continue their habit;

c) arrangements which exist, or might exist in the future, for supplying drugs to either of the above categories of drug misuser;

iii) Consider the benefits or otherwise of decriminalization or legalization of some or all controlled drugs.

 

The BMA published its report on drug misuse in 1997 (BMA, 1997) addressing parts i) and ii) of the ARM resolution. In considering part iii) of the resolution, the BMA felt that questions regarding the legalization or decriminalization of controlled drugs should be considered only with regard to their therapeutic use by patients under medical supervision, for particular medical conditions. As a subject of wide public and professional interest, the potential therapeutic benefits of cannabis and cannabinoids have therefore been reviewed and are published here as a separate policy document.

In 1997 the BMA’s Annual Representative Meeting resolved

That this Representative Body believes that certain additional cannabinoids should be legalized for wider medicinal use. This report supports and develops this policy statement by describing the scientific evidence for wider medicinal use of cannabinoids and defining future research needs.

The Royal Pharmaceutical Society of Great Britain also believes that action is needed. The Society has called for further clinical research into the potential therapeutic uses of cannabinoids, and while this is underway, that doctors should be able to prescribe cannabinoids for specific serious disorders, at least for a trial period.

Cannabis sativa

The plant Cannabis sativa, from which cannabis is obtained, has a long history as a medicine. Over the centuries, its uses have included the treatment of pain, asthma and dysentery, the promotion of sleep, the suppression of nausea and vomiting and the abolition of convulsions and spasms (Mechoulam, 1986). In this country, the medicinal use of cannabis was particularly prominent in the nineteenth century. However, it remained permissible for British doctors to prescribe cannabis (as a tincture for oral administration) until 1971. More recently, claims have been made for the beneficial effects of cannabis and cannabinoids (a family of carbon, hydrogen and oxygen containing compounds which constitute the active ingredients of cannabis). This interest has coincided with a renewed interest in and increasing acceptance of herbal medicine and ‘natural’ remedies.

The legal situation

Cannabis and certain psychoactive cannabinoids and derivatives (cannabinol and its derivatives tetrahydrocannabinol and 3-alkyl homologues of cannabinol or its tetra hydro derivatives) are classified under Schedule 1 of the Misuse of Drugs Act 1971 as having no therapeutic benefit. They therefore cannot be prescribed by doctors or dispensed by pharmacists and can only be possessed for research purposes with a Home Office licence. If the research involves clinical trials, further permission is required from the Medicines Control Agency.

Two other non-psychoactive cannabinoids, cannabidiol and cannabichromene, despite their structural similarity to cannabinol, are not controlled drugs; although not licensed as medicines, there is nothing to prevent a doctor from prescribing them. A further two cannabinoids, dronabinol and nabilone, can be prescribed by doctors.

Nabilone, a synthetic analogue of Δ⁹-tetrahydrocannabinol (THC), is licensed for prescription to patients with nausea or vomiting resulting from cancer chemotherapy which has proved unresponsive to other drugs. A change in international law has allowed the prescription of Δ⁹-THC (dronabinol) for the same indication. Following advice from the World Health Organization to the United Nations Commission on Narcotic Drugs that dronabinol had demonstrated medical uses in combatting nausea and vomiting caused by cancer chemotherapy, the United Nations Commission on Narcotic Drugs rescheduled dronabinol under the UN Convention on Psychotropic Substances 1971. This in turn led the UK Government, a signatory to the UN Convention, to reschedule dronabinol from Schedule 1 to Schedule 2 under the Misuse of Drugs Act. Dronabinol is currently unlicensed in the UK and has to be specially imported for prescription on a ‘named patient basis’ for the same indication. Prescribing unlicensed medicines puts greater responsibility on the doctor, as their effects may be less well understood than those of licensed products.

International developments

In 1996 in the United States, Arizona passed a law permitting doctors to prescribe any drug in Schedule I (which are not approved by the Food and Drug Administration) including cannabis, but this was effectively repealed by the FDA the following year. In the same year Californian voters approved a state law eliminating criminal penalties for those who grew or used small amounts of cannabis for medical purposes if they could show that they were acting on the recommendation of a doctor. However, under federal law, cannabis remains an illegal narcotic, and doctors who recommend its use to patients have been threatened with prosecution and loss of their prescription privileges under Drug Enforcement Administration regulations.

In Italy patients who need cannabis for therapeutic purposes are allowed to grow their own supply of the plant once they have gained certification from their local authority and in Germany nabilone is unlicensed but can be imported for prescription.

Until August 1997, doctors in the Netherlands were able, unofficially, to issue prescriptions for cannabis which were dispensed by pharmacists. However, acting on a recent report by the Dutch Health Council (1996) which concluded that there was insufficient proof of its medicinal benefits, the health inspectorate has banned the prescription of cannabis. It remains available from ‘brown’ coffee shops, but is of unregulated quality. In most other European countries cannabis and cannabinoids remain illegal for therapeutic use.

Prescription of unlicensed medicines in the UK (Drug and therapeutics bulletin, 1992)

As an unlicensed medicine, the prescription of dronabinol or of nabilone for an unlicensed indication, brings with it extra responsibilities for the doctor. The legal responsibility for prescribing any medicine lies with the doctor, for an unlicensed medicine, or for an unlicensed indication, (one which is not on the data sheet) the prescriber can be particularly vulnerable. In common law doctors have a duty to take reasonable care and act in a way consistent with the practice of a responsible body of their peers of similar professional standing. Not to meet this standard would lay the doctor open to allegations of negligence.

When prescribing outside a licence, it is important that doctors should do so knowingly; where possible, the drug’s licence status should be explained to patients in sufficient details to allow them to give informed consent. This will involve explaining that the effects of an unlicensed product may be less well understood than those of a licensed product. Prescribers need to be fully informed about the uses and actions of the product and assured of its quality and source.

Scope and purpose of the report

This report provides an outline of the pharmacology of cannabis and cannabinoids relevant to medicinal aspects, followed by short reviews of the main proposed therapeutic uses. These reviews are presented as follows:

• Suggested therapeutic indication and its medical importance.

• Existing pharmacological treatments and their shortcomings.

• Human studies on the use of cannabis/cannabinoids in the condition under discussion.

• Further research needed.

• Conclusion and recommendations.

The literature covered is not claimed to be exhaustive, but it is believed to be sufficiently comprehensive to provide an overall picture of the area reviewed. In many areas definite conclusions are not possible because of the absence of data. In such cases the type of data required is suggested. A glossary of terms used in this report is given in Appendix I.

2
Pharmacology

Constituents of cannabis; natural and synthetic cannabinoids

Cannabis sativa a...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Editorial Board
• Board of Science and Education
• Acknowledgements
• List of tables
• List of figures
• 1 Introduction
• 2 Pharmacology
• 3 Therapeutic uses
• 4 Adverse effects of cannabis and cannabinoids in clinical use
• 5 Dosage and routes of administration
• 6 Future prospects
• 7 Summary and recommendations
• Appendix I: Glossary
• Appendix II: Anecdotal evidence
• Apendix III: Summary of research studies
• References
• Index