Louis Roller takes a look at epilepsy, including a medicinal cannabis update
Epilepsy is defined as a chronic seizure disorder, or group of disorders, characterised by seizures that usually recur unpredictably in the absence of a consistent provoking factor.
Seizures are characterised by an excessive, hypersynchronous discharge of cortical neurone activity, which can be measured by an electroencephalogram (EEG). In addition, there may be disturbances of consciousness, sensory motor systems, subjective well-being, and objective behaviour; seizures are usually brief, with a beginning and an end, and may produce post seizure impairment.
The aim of drug treatment of epilepsy is to prevent seizure recurrence preferably with monotherapy and to minimise adverse effects. If the seizures are not controlled by the maximum tolerated dose of the first antiepileptic drug, it should be replaced by a second drug.
Prescribers and pharmacists should be aware of interactions between antiepileptic medicines, other medicines including oral contraceptives and some complementary medicines. These can have significant effects on antiepileptic medicines and vice versa.
Drug interactions with antiepileptic agents are based in large part on pharmacokinetic mechanisms. Most prominent are induction or inhibition of enzymes of the cytochrome P450 system, which is of central importance for metabolic elimination of lipophilic xenobiotics.
The pharmacist is the best-placed person to identify and handle those interactions. Additionally, pharmacists should be aware that non-adherence is a common cause of therapy failure.
Patients with diagnosed epilepsy should be made aware that:
- most can achieve complete control of seizures
- most can lead a normal life—they can expect to form relationships, marry, have a normal sexual life and have normal children
- they require good dental care, especially if taking phenytoin
- a seizure in itself will not usually cause death or brain damage unless in a risk situation such as underwater swimming
- people cannot swallow their tongue during a seizure
- they should take special care with open fires
- they should avoid alcohol as intoxication is extremely harmful
- adequate sleep is important and that sleep deprivation is harmful
- they should avoid fatigue
- they should be advised to shower rather than taking a bath
- they should avoid stress
- they should avoid prolonged flashing lights if photosensitive, such as those emitted by video games
- they must not partake in flying and parachuting, motor racing, mountain and rock-climbing, high diving, scuba diving, hand-gliding and abseiling
- they should not partake in aiming sports (such as archery and pistol shooting), contact sports such as boxing, football (all sorts), competitive cycling for children with absence epilepsy, bathing and swimming, gymnastics, especially activities such as trampolining and climbing on bars, ice-skating and skiing and javelin throwing.
Language: It is important that pharmacists and other health professions, family and friends do not stigmatise patients with epilepsy (or any other disease, for that matter). They must not be called ‘epileptics’, but ‘a person with epilepsy’ or ‘with seizure problems’.
No one wants to be described as a disease. “I do not want to be a disease, I am a person with a condition, please treat me with the dignity that I deserve; I am a person with epilepsy, not an epileptic”.
Medicinal cannabis for epilepsy
The active ingredients in cannabis include: tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol, tetracannabivarin and some 483 known compounds in the plant as well as 65 other cannabinoids.
Cannabis is one of the oldest psychotropic drugs and its anticonvulsant properties have been known since the last century.
Recently, there have been some open-labeled studies in the US of Epidiolex (a drug derived from cannabidiol or CBD). Epidiolex is a purified, 99% oil-based extract of CBD that is produced to give known and consistent amounts in each dose. Cannabidiol does not cause a high.
In Australia, the Poisons and Therapeutic Goods Amendment Regulation 2016 which was approved to allow doctors to apply to state departments of Health (NSW – legalised 1 August, and Victoria- legalised April 12 with 2017 access) to prescribe cannabis-based products that are not on the Australian Register of Therapeutic Goods.
This change increases the options available for doctors as it means a broader range of cannabis-based medicines can be prescribed while evidence-based research continues to further investigate the role medicinal cannabis can play.
Some products have the tetrahydrocannabiol removed so there is no ‘high’ and will be approved for children with severe drug-resistant epilepsy.
Sativex (Oral mucosal spray; contains 27 mg THC and 25 mg cannabidiol) is now available on the Australian market (see eMIMs).
Cultivation of cannabis is now occurring in a number of states.
We shall have to await developments.
Associate Professor Louis Roller, from the Faculty of Pharmacy and Pharmaceutical Sciences Monash University, was the 2014 recipient of the PSA Lifetime Achievement Award.