By Dr Janelle Trees, BSC (HONS), MBBS (HONS), FRACGP
Smoking, eating, inhaling vapours, rubbing it on, even as a skin patch or a suppository: there is a great deal of work being down to find the most pleasant and effective ways to get cannabinoids into the body. Cannabinoids, at present mainly two compounds called THC and CBD, are the effective ingredients of marijuana, which are used to make cannabis-based medicines.
Smoking is the familiar way of taking marijuana recreationally. Many people who should probably become medicinal marijuana patients have self-medicated with marijuana by smoking it illegally for years. Smoking marijuana carries similar risks to smoking tobacco. And tobacco is often smoked with it, anyway. Regular marijuana smokers are at risk of chronic airways limitation (emphysema) and lung cancer.
Hemp oil e-liquid or vape oil is made to ingest by vaporising (‘vaping’). The oil is heated and the vapour inhaled, using a specially made electronic pipe. Vaping helps the patient avoid inhaling the damaging substances present in smoked marijuana—like carbon monoxide and burnt particles–while having the same rapid effect. The effects of cannabinoids taken this way last for a shorter time than medicines that are swallowed, for example.
And doctors don’t know much yet about the safety profile of vaping. Whether it is safer than smoking is still open for discussion and under research. Some cannabis oils are mixed with substances like propyline glycol or polyethylene glycol – substances which should not be inhaled. It may be safer to vape whole flowers or leaf. But vaping anything can aggravate asthma. The only thing that should be come into your lungs, really, is air.
Ingesting cannabis-based medicines is a more benign way to take it. Capsules and oils are taken this way. Absorption of eaten cannabis is reduced by metabolism in the stomach and liver, though, making less of the medicine available. (Doctors call this ’first pass metabolism’.) Taking medicines regularly can create a steady level of cannabinoids in the bloodstream (eg for management of constant pain).
One way to avoid this loss of benefit is by mucousal absorption. Drops, cannabis oil or tincture taken in the cheek or under the tongue, have a fast medicinal effect. Some are taken under the tongue and then swallowed. Available in Australia, Sativex spray is absorbed this way. Some medicines combine the fast onset of mucous absorption with the longer-lasting availability of intestinal absorption.
Tinctures are hemp oil mixed with other oils or alcohol. Tinctures often taste better than plain oil. They may be mixed with coconut oil, peppermint or other strongly-flavoured oils. The taste of pure hemp oil has been described as ‘like eating a handful of grass and dirt’. Oils are sometimes supplied in a syringe or with a syringe so that you can measure tiny doses—often a tenth of a millilitre. Some people find taking the medicine easier if they drink juice (or even cider vinegar in water) after holding the drops under the tongue for a minute or so.
Another way of avoiding first pass metabolism of the medicine is to use it rectally. This is a useful route of administration for patients who have difficulty swallowing. This can be especially helpful for palliative patients. Some cancers and neurological diseases make it difficult or impossible to swallow towards the end of life.
Edible and rectal medicinal marijuana both have slower onset and can have effects that last much longer. These factors need to be taken into consideration when you and your doctor are working out the best dose for you. The longer, stronger effect of edible or rectal cannabis-based medicines means that any negative effects can last longer, too. Possible side effects include anxiety, paranoia, palpitations and low blood pressure. Your doctor, possibly working together with an Australian medical marijuana clinic, will discuss the risk of these side effects with you and help you avoid them by starting with a low dose and increasing to your optimal dose slowly.
The research and industrial development of safe, reliable methods of administration of medicinal marijuana are ongoing. Products available in Australia now, prescribed by the doctor and approved by the necessary government bodies, are mainly for oral use. As further studies provide us with more information about the use and efficacy of other forms of cannabis-based medicines, we can look forward to other means of administration becoming available, like topical creams that can rubbed onto painful areas or patches that can be used for long-term symptom coverage, suppositories, or edible medicines in other forms.