Salma Boudhan provides her insights…
Salma Boudhan is the pharmacy manager for Transvaal Apotheek’s medicinal cannabis programme. Her team provides pharmacy services for cannabis-based medicines for patients throughout the Netherlands. Transvaal has dispensed medicinal cannabis (flos) since it was legalised in 2003, and high quality whole cannabis oil extracts for sublingual administration since 2015. A typical patient arriving at Transvaal are those suffering from cancer pain, nausea and vomiting; neuropathic pain; or epilepsy.
The role of pharmacists is just as important as prescribers. Pharmacists support prescribers with patient medicine reviews, and talk with patients about a medicines risks and benefits. They help to minimise medicine misuse and harm, and seek feedback on safety, effectiveness and adverse reactions.
Administration
Oral dose forms (oil extracts) are an increasingly popular, what advice do you give patients on safe use?
“In accordance with their doctor’s prescription, we suggest that patients start low and go slow. As a starting dose for oil, we recommend to use 2 drops (0,05ml) under the tongue, 3 times a day and increase the dose until the desired effect is achieved. The maximum dosage is 10 drops (0,25ml), 3 times a day.
The ‘steady state’ concentration of THC/CBD and the active metabolite is reached after 1-2 weeks. This time span should be taken into account for the assessment of the medicines effectiveness for the patient.”
Vaporization is a popular mode of administration, what advice do you give patients on safe use?
“We recommend patients inhale 1-2 times a day until the desired effect is achieved or until (psychotropic) side effects occur. This means they have had too much. Per inhalation, we recommend patients wait at least 5 minutes between the inhalations.
Patients should take into account that inhaling cannabis results in a higher uptake than when using other administration routes. Patients have to dose carefully when changing to a different variety, especially if they have previously used cannabis with a lower content of THC/CBD.
The ‘steady state’ concentration of THC/CBD and the active metabolite is reached after 1-2 weeks. Like oral dosing, this time span should be taken into account for the assessment of the medicines effectiveness for the patient.”
Safety
What do you tell patients about the safe and effective use of medicinal cannabis?
“First we ask the patient what they already know about medicinal cannabis. Then we inform them about the mechanism of action, how to use it, the dosage regimen, possible side-effects, how to safely store it. Finally we make sure that the patient takes notice of possible interactions with other medicines or contra-indications (certain conditions where medicinal cannabis should not be used).
In a follow-up discussion we ask the patient about their experience with the use of medicinal cannabis, with extra attention to side-effects and effectiveness.”
What are the key risks of using cannabis as a therapeutic product?
“The only known contra-indications include schizophrenia, arrhythmia and other heart conditions. We work closely with prescribing doctors and also provide adequate instructions to patients about the benefits and risk of their medicines.”
Are you aware of any patients that have experienced cannabis interactions with other medicines?
“We know that cannabis is metabolised by CYP450 enzymes. When taken together with other medicines metabolised by the same enzymes, there may be the potential for drug-drug interactions. We discuss with patients about the risk of using such medicines concurrently, or recommend alternative medications.”
From a pharmacist’s point of view, what are the actual and potential complications with medicinal cannabis?
“The biggest risk is getting high and triggering psychoses (especially with psychiatric patients) or worsening current depression. There are risks in prescribing in the elderly, and the potential long-term effects on children are still unknown.”
What is the role of the pharmacy profession in ensuring patient safety with the use of these medicines?
“Pharmacovigilance (see Section 8) is an important role of a pharmacist. We seek feedback from patients on the safety, effectiveness and adverse reactions they experience from their medicine use. We are also required to provide adequate instructions and honest information to patients about the benefits and risk of their medicines.”
Do you encounter diversion for misuse or abuse?
“Not often. We identify this issue by monitoring the quantities dispensed and the frequency of dispensing. We make an agreement with the patient to avoid further misuse. If this doesn’t help, we consult the prescribing doctor and find solutions to the problem.”
Do you have any good advice (tips) for pharmacists starting out?
“Get training or read a lot into the subject, because patients are generally quite well informed but also misinformed.”