Cannabis in Medicine

Archeological evidence indicates that ancient cultures have employed the cannabis plant as herbal medicine, to treat a broad spectrum of indications. However, since the 20th century it has been regarded as a schedule 1 drug.

Medical Cannabis in Israel

Medical cannabis in Israel is only approved once all conventional treatments have failed. A committee assigned by the Ministry of Health has approved medical cannabis for several indications (adopted the ministry of health document 106, March 2013):

  • Oncology: For nausea, vomiting and pain associated with chemotherapy/ pain associated with metastatic cancer.
  • Gastroenterology: Crohn’s disease, Ulcerative Colitis.
  • Neuropathic pain.
  • Inflammatory disease: Cachexia in AIDS patients (above 10% body weight loss)  or with CD4 levels below 400.
  • Neurology: Multiple Sclerosis, Parkinson’s Disease, Tourette Syndrome.
  • Palliative Care.
  • Exceptional cases are evaluated by the approval comittee.

Routes of Administration

The currently approved routes of administration are inhalation, either by smoking or vaporizing, or orally by consumption of oil extracts.

The superiority of oil products over smoking, from medical and pharmaceutical aspects is indisputable. Oil products can reliably be manufactured to produce a medical product with high reproducibility and repeatability, with consistent amounts of active ingredients.  Cannabis flowers cannot offer equivalence accuracy and consistency.

Development of herbal medicines encompasses fundamental challenges that require specialized research. The plant is composed of diverse components and hence advanced analytical tools are required in order to differentiate them. 

Pharmacokinetics

The bioavailability of THC following smoking is highly variable and can range between 2% to 56%. A steep elevation in plasma concentrations results in peak plasma concentrations within minutes and rapid elimination from the circulation. Due to first pass metabolism in the liver, the oral bioavailability of THC ranges between 10-20% . Despite the metabolism of THC in the liver, the central metabolite, 11-OH-THC not only possess similar spectrum of activities but was also found to be a more potent cannabinoid than THC. Therefore, following oral administration of THC, the combined effectiveness of THC and 11-OH-THC should be taken into account as it prolongs the effectiveness of THC. Following oral administration peak plasma concentrations are reached 1-2 hours post delivery and THC plasma concentrations are maintained over several hours.

graph3

Based on data published by Wall et. al 1981 and Lindgren et.al 1981.

graph2

Based on data published by Wall et. al 1981 and Lindgren et.al 1981.

graph1

Based on data published in Sativex monograph, Marinol monograph, Nadulski et. al 2005, Kauert et. al 2007.

Bioavailability of CBD is much less studied. Nevertheless, it was found that following smoking the bioavailability of CBD ranges between 11% and 45% with a plasma pattern that resembles the one obtained for THC.

Cannabis products as potential therapeutic Agents

Recent research reveals the potential therapeutic effects of various cannabis components and not only as relieving the symptoms. Though most research is focused on THC and CBD additional studies are carried out to elucidate the activities of other cannabinoids. Most of the studies are in vitro and in vivo laboratory research and very few well designed clinical studies have been conducted. Searching the NIH clinical trials site for “medical cannabis” results in 117 studies, most of which are associated with smoked marijuana and among the oral route of administration dronabinol  and sativex predominate. Clearly, additional studies performed with alternative formulations are essential for gaining better knowledge of cannabis and cannabinoids therapeutic potential.

 

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