The science of medical marijuana

Q. There’s strong public support, but is there scientific backing for medical marijuana?

A. Otago University professor of neuropharmacology Paul Smith says although the Government’s movements towards legalising medical marijuana was positive, there were a number of conditions for which the evidence base was not entirely consistent or convincing.

‘‘’Cannabis-based medicine’ (CBM) are not ‘magic bullets’. The evidence that they work for some conditions like neuropathic pain is not entirely consistent or convincing, but they do appear to help some people. So, it is a question of benefit vs burden for a particular condition.

‘‘In the case of terminal illness, there is not much reason to have concerns because the harm will be minimal and the patient may benefit. There are also issues around how CBMS might be taken, and whether they can be delivered as a spray to avoid potential harm from smoking.

‘‘This avoids the potential harm of smoking cannabis, which is associated with damage to the lungs even if only cannabis is used in the cigarettes, a point often overlooked in the medicinal cannabis debate.

‘‘It’s important to be clear about what ‘cannabis-based medicine’ (CBM) actually is. Cannabis the plant contains hundreds of chemicals and about 66 that are unique to the cannabis plant.’’

Smith said some of the products currently on the market had different levels of the psychoactive ingredient, THC, while others may be missing the chemical entirely.

Comments gathered by Science Media Centre New Zealand.