The research of new therapeutic strategies for neuropathic pain represents a major current priority. Important drawbacks to advance in the development of these therapies are the limited translational value of the animal models now available and the elucidation of the complex neuronal and immune pathophysiological mechanisms underlying neuropathic pain. One of the neurotransmitter systems participating in neuropathic pain control that has recently raised a particular interest is the endocannabinoid system. This system is highly expressed in neurons and immune cells, and it plays a crucial role in the development of neuropathic pain. Preclinical studies have provided important findings, revealing the potential interest of the endocannabinoid system for the treatment of neuropathic pain. These studies have reported the analgesic effects of cannabinoid agonists in multiple neuropathic pain models, and they have identified specific targets within this system to develop more effective and safe analgesic compounds. However, further studies using more relevant neuropathic pain animal models are required to confirm these interesting results. Several clinical studies suggest that cannabinoids significantly reduced neuropathic pain, although most of these trials fail the required standards of quality. The different pain patient populations included in the systematic reviews also make it difficult to get adequate conclusions. Therefore, additional clinical trials that consider an adequate number of patients, the use active treatments as controls, and longer duration of administration are required to have an adequate profile of the effectiveness and safety of cannabinoids in neuropathic pain.
Preclinical and clinical studies highlight the endocannabinoid system as a promising target for neuropathic pain. Additional improved animal models and high-quality clinical trials must be implemented.
Laboratori de Neurofarmacologia, Departament de Ciències Experimentals i de la Salut (CEXS), Facultat de Ciències de la Salut i de la Vida, Universitat Pompeu Fabra, Barcelona, Spain
Corresponding author. Address: Laboratori de Neurofarmacologia, Universitat Pompeu Fabra, Parc de Recerca Biomedica de Barcelona (PRBB), C/Dr Aiguader, 88, 08003 Barcelona, Spain. Tel.: +34933160824; fax: +34933160901. E-mail address: email@example.com (R. Maldonado).
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
Received September 28, 2015
Received in revised form November 6, 2015
Accepted November 6, 2015