Dr Jürgen Fleisch provides his insights…

Trained as an anaesthesiologist in Germany, Dr Jürgen Fleisch then undertook a fellowship in pain medicine (Portland, Oregon). He now practices anaesthesiology and pain therapy in the Netherlands at the Leiden University Medical Centre. For the last decade, his close cooperation with the Department of Oncology means he regularly treats symptoms in cancer patients using medicinal cannabis. In both clinical settings, he typically encounters two types of patients: (i) those with advanced cancer experiencing loss of appetite and possibly nausea and vomiting, often having tried many other medications beforehand, and, (ii) those that experience central neuropathic pain after unsuccessful trials of more common medications.

Do you have any advice for doctors starting out prescribing?

“My advice for clinicians who are starting to prescribe medicinal cannabis is to stick to specific indications where there is a solid foundation of evidence for its use. This allows us to gain experience with the effects of this medication in a specific adult patient population.

Recreational cannabis users are, in my opinion, not a good patient category to start with. They may put considerable pressure on the clinician to prescribe for dubious indications.”

How is prescribing medicinal cannabis different to prescribing other medicines?

“They are like any other medicine. However, many patients will have an opinion about cannabis. For some it has a rather negative connotation as being a substance of abuse.”

What are the key benefits of cannabinoids as a therapeutic product?

“There are three main advantages of medicinal cannabis in general over other medicines used in my field of pain medicine, these include that:

  • there are analgesic effects on neuropathic pain syndromes and, depending on the medicine type, anti-emetic and appetite stimulating effects. This is especially important for cancer patients with pain.
  • there are no known organ damaging side effects in the adult patient, aside from the potential risk to mental health. As compared to, for example, those linked with using NSAIDs when used inappropriately.
  • some cannabis flos variants have a soothing effect, which some patients greatly appreciate.”

What do you think are prescribing practices that improve patient outcomes?

“For patients with no experience using cannabis products, the possible psychological side effects can be distressing. In order to avoid this we advise patients’ to start with low dosage and use the medicine in a quiet and relaxing environment.

In our experience, it is advantageous to prescribe cannabis flos as an inhalational agent, administered by vaporization, as it creates more rapid analgesic effects and has a more reliable absorption profile.”

Aside from eliminating the harms from smoking, what are the benefits of administration by vaporization?

“Using vaporized cannabis flos is the preferred means of use by most patients, especially when compared with an oral application. This is due to the more rapid effect by inhalation.

With vaporization cannabis flos is heated to a specific temperature without burning it. Cannabinoids and terpenes are released in a vapour which is directly inhaled.

There are three main advantages of administration by vaporization is that it:

  • allows for exact dosing,
  • leads to a rapid effect, and
  • avoids the disadvantages of smoking (i.e., no tar, ammonia, carbon monoxide).”

Patient considerations

Thinking about a first consultation with a patient, how do you start a conversation about medicinal cannabis?

“There are two types of discussion around the use of medicinal cannabis:

The elderly, cannabis naive patient:

An elderly cancer patient may be hesitant to use cannabis as a medication. This likely is related to prejudices about cannabis being a product for ‘recreational’ use. With these patients, I rarely discuss the use of these medicines during a first consult. If the patient is eligible and several other therapies did not provide sufficient pain relief, I then mention medicinal cannabis as a possible option. This allows the patient and his/her family to contemplate that treatment option until the next appointment.

The experienced patient:

There may be patients who have extensive experience using cannabis recreationally. They may be actively looking into medicinal cannabis as a potential adjunct to their pain therapy. These patients emphasise the ineffectiveness or side effects of other therapies, and may push clinicians towards prescribing a cannabis product. With these patients the topic must be discussed fully during a first consult. The main question during this consult is are they at all eligible to receive medicinal cannabis.”

Are you aware of patients experiencing interactions with medicinal cannabis and other medicines?

“Indeed, we do see patients who experience drug interactions using cannabinoid therapeutics alongside other CNS depressant medications (e.g. opioids).

Sedative effects can be enhanced especially in the geriatric population. Severe drowsiness and hallucinations can also be provoked.

Aside from drug interactions, the smoking of cannabis is related to an increased risk of myocardial infarction and stroke. Cannabis as a trigger of myocardial infarction is plausible, given its cardio-stimulatory effects, which may cause ischemia in susceptible hearts. Carboxy-hemoglobinemia from the smoking of cannabis may also contribute to ischemia. Smoking is never recommended.”

Do you encounter diversion for misuse or the abuse of medicinal cannabis? How do you identify this issue in your practice?

“During the period when Dutch health insurers widely reimbursed medicinal cannabis, we had frequent discussions with patients, best described as ‘recreational users’, about their eligibility.

Patients of this group, who were already using large amounts of cannabis, were requesting access for rather dubious indications. Some patients were seeing medicinal cannabis as a cheap way to get a ‘recreational drug’ which they were already abusing.”

How do you deal with diversion for misuse or abuse in your practice?

“This patient group can be quite challenging. They may put pressure on clinicians to prescribe medicinal cannabis as the only means to relieve their pain. Mentioning misuse and abuse can provoke abrupt reactions.

Clinicians should be coherent in prescribing medicinal cannabis only for indications with enough evidence for beneficial effects (e.g. analgesic for neuropathic pain, appetite stimulation etc). Misuse and abuse should be discussed openly if they become apparent.”