Titration of dose
Like with other medicines, individual patients will respond differently to cannabis-based medicines. Their response depends on the cannabis product used, the condition being treated, the duration of treatment, how it is administered and genetic predispositions.
A patient’s doctor generally provides advice regarding dose titration (dose adjustments to a desired effect) to achieve an optimal daily dosage. Titration helps patients to obtain the desired therapeutic effects and to minimise undesired effects.
Many patients will titrate their dose in the first weeks of therapy. Pharmacists should provide guidance, as per the prescription, on:
- the starting dose and titration up and down (minimum and maximum dose), including how dosage adjustments would be made based upon the dose form
- how to find an optimal daily dosage based on the severity of the patient’s condition and changes in their other medication
- how to maintain their daily dosage.
Keep in mind that the pharmacological effects are dose related and subject to inter-patient variability. Systemic absorption will be different in intensity and timing, depending on the route of administration (refer back to table).
Be cognisant of possible medicine and food interactions, and potential for adverse reactions, based on the patient’s total medicine regimen. Discuss ways to reduce the risk of side effects occurring. Explain that these are novel medicines and there may be yet unknown adverse reactions to these medicines, which should be reported.
Encourage your patient to tell you about any adverse effects. Report these immediately to the Centre for Adverse Reactions Monitoring within the New Zealand Pharmacovigilance Centre (nzphvc.otago.ac.nz/reporting). The more details provided, the better – the medicine name and dose suspected of causing the reaction is necessary, alongside a list of symptoms, signs, laboratory results and past medical history.
Patients should avoid driving, operating machinery or engaging in any potentially hazardous activity under the influence of cannabis-based medicines. THC and CBD may produce undesirable effects, such as drowsiness, which will impair judgement and driving performance.
THC-containing medicines are often considered desirable psychoactive substances. Like other controlled drugs, these medicines require the same guidance and considerations by pharmacists to limit diversion and misuse.
Cannabis-based medicines should be stored in the official pharmacy container, in a safe and secure place where young children cannot reach, and away from heat and direct sunlight (eg, in accordance with label storage conditions).
If travelling internationally, patients should be reminded to check that it is legal for them to take cannabis-based medicines into any countries they are travelling to or through. Legal status will vary between countries.
Request feedback from your patient regarding side effects, and determine if the desired effect has been obtained and maintained over time. In direct consultation with the prescribing doctor, discuss a plan to modify or stop treatment at a particular dosage if no significant effect has been seen, if intolerable side effects have occurred, or if dependence has been identified.
Confirm a protocol for returning unwanted or unused cannabis-based medicine and, if required and necessary, the device used to administer it. Out-of-date or unwanted medicine should be taken back to the pharmacy for safe disposal.