Neuropathic Pain

Neuropathic pain is associated with a functional abnormality of the nervous system usually as a result of underlying damage to neurons. Clinical features of neuropathic pain include the presence of an abnormal, unpleasant sensation (dysesthesia) that frequently has a burning or electrical quality with an occasional paroxysmal, brief, shooting, or stabbing quality. It has been estimated that as much as 7% to 8% of the population is affected with neuropathic pain, and in up to 5% of the population it may be severe. Neuropathic pain can be very difficult to treat with only some 40-60% of patients achieving partial relief. Five drugs are currently indicated for neuropathic pain in one or more of the seven major markets (US, Japan, France, Germany, Italy, Spain and the UK). Driven mainly by sales of Lyrica (pregabalin), Cymbalta (duloxetine) and Lidoderm (lidocaine 5% patch), the neuropathic pain market is currently estimated to be worth $4 billion and is forecasted to exceed $5.5 billion by 2015.
The use of THC for the treatment of neuropathic pain has been well-documented and there is an abundance of anecdotal evidence to support its use. This includes:

Svendsen, Jensen, and Bach (2004) conducted a randomized, double-blinded, placebo-controlled, crossover trial evaluating the effectiveness of dronabinol (THC) on central neuropathic pain in 24 patients with multiple sclerosis. In their study, it was found that pain intensity was significantly lower during the dronabinol treatment phase than with the placebo treatment phase.

Wade, et al (2003) examined the effectiveness of a sublingual spray form of plant-derived cannabis medicinal extracts in improving neurogenic symptoms unresponsive to standard treatments. In this double-blinded, randomized, placebo-controlled trial involving 24 patients presenting neurogenic symptoms (18 patients with MS, 4 with spinal cord injury, 1 with brachial plexus damage, and 1 with a limb amputation due to neurofibromatosis), it was found that pain relief, as well a reduction of spasticity, associated with the cannabinoid arm was significantly superior to placebo.

Berman, Symonds, and Birch (2004) conducted a randomized, crossover, placebo-controlled trial investigating two cannabis-based medicinal extracts for neuropathic pain resulting from brachial plexus avulsion. In this study, 48 patients received THC, a mixture of THC/cannabidiol (CBD), or placebo in a sublingual spray over a six-week period. Both THC and THC/CBD significantly improved pain as well as sleep quality and quality of life versus placebo.

For these reasons, Relivar has merit as a novel pharmaceutical candidate, to treat neuropathic pain, nausea/vomiting and possibly other conditions.