Applied Evidence

Medical Cannabis: A guide to the clinical and legal landscapes

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A tolerable therapeutic starting point is a THC:CBD ratio of 1:1.

THC has tremendously complex capacity for activation and inhibition within various neuronal circuits, resulting in effects on mood, appetite, and movement.1,7 Adverse effects associated with Cannabis are wide-ranging: Most commonly, nausea, drowsiness, fatigue, dry mouth, and dizziness are reported alongside cognitive effects. Rarely, tachycardia, hypotension, hyperemesis, and depression can be seen.

Clinical implications and indications

Clinical indications for legal medical Cannabis vary by state; typically, indications include human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome (AIDS), cachexia, cancer, glaucoma, epilepsy and other seizure disorders, severe and chronic pain, spasticity from neurodegenerative disorders, and irritable bowel syndrome and Crohn’s disease, as well as a wide range of less-universal diagnoses. A patient may have a so-called qualifying diagnosis (ie, having the potential to allow the patient to be certified to purchase and use Cannabis) in one state but not have the same standing in a neighboring state, posing a complex legal issue. Given the significant complexities of performing medical research with plant-based Cannabis in the United States, little research has been done. The result? Policymakers are grappling with questions that only scientific research can answer:

  • For which conditions does Cannabis provide medicinal benefit equal to or superior to alternatives?
  • What are the appropriate dosages (or CBD:THC ratios), formulations (plant-derived or synthetic), and routes of administration (smoked, ingested, or topical) for various conditions?

Bird’s-eye view of clinical research. A meta-analysis of isolated synthetic and plant-based cannabinoids for medical use was published in 2015.10 The analysis included more than 6000 patients in 79 trials, most of which assessed whether dronabinol or nabilone (both synthetic isolates) were effective compared to placebo or alternative non-Cannabis-based therapy. The studies examined chemotherapy-induced nausea and vomiting, appetite stimulation in HIV and AIDS, chronic pain, spasticity, depression and anxiety, sleep disorders, and psychosis.

Twenty-eight studies assessed chemotherapy-induced nausea and vomiting. All of these studies indicated a greater benefit from cannabinoids than from alternative antiemetic regimens and placebo; however, that finding did not reach statistical significance across all studies.

There was moderate evidence to suggest the use of Cannabis for neuropathic and nonneuropathic cancer-related pain. However, there is an increased short-term risk of adverse events with synthetic isolates dronabinol (when used for pain) and nabilone (when used for nausea and vomiting).

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