Investigation of Cannabinoid Receptor Agonist Dronabinol in Patients With Functional Chest Pain

About 200,000 new cases of Functional Chest Pain (FCP) are diagnosed annually in USA. FCP is associated with poor quality of life and high health care expenditure. Gastroesophageal reflux disease (GERD), esophageal motility disorders, and psychological disorders may cause FCP. However, the mechanism(s) for FCP continue to be explored and include central and peripheral hypersensitivity as well as biomechanical dysfunction of the esophageal wall. CB1 receptor activation in synaptic clefts fine tunes neuronal firing and may in fact quell the over excitation associated with hypersensitivity. Dronabinol, a cannabinoid receptor agonist with a preference for CB1 over CB2, is believed to reduce the esophageal hypersensitivity. CB1 receptors are located primarily on central and peripheral neurons (including the enteric nervous system) and myenteric plexus where they modulate neurotransmitter release. Activation of pre-junctional CB1 receptors may reduce excitatory enteric transmission and conceivably improve esophageal hyperreactivity and hypersensitivity, the hallmarks of FCP. Previously, it was shown that Chest Pain Symptoms were greatly reduced when patients took 5 mg Dronabinol twice daily. Patients had very few side effects from this regiment although sedation was reported. The goal of this study focuses on reducing the dose of Dronabinol to 5 mg every other day, or essentially, one quarter of the dose. The effect of Dronabinol varies with CB1 receptor density in various tissues. It is hypothesized that at this reduced dose relief of chest pain will still be achieved without the sedating effects. More so, Dronabinol at 5 mg twice daily failed to produce any adverse metabolic outcomes including measures of glucose, LDL, triglycerides, leptin, or transaminases. Dronabinol treatment tended to improve some of these measures although the study only lasted 28 days. Currently the hypothesis is that lower doses at a protracted time course will again fail to perturb homeostasis.