Gonyautoxin 2/3 in the Treatment of Acute Back Pain: A Clinical Proof-of-concept Study

Inclusion Criteria: * Man or woman patients between 18 and 75 years old. * Acute back pain episode without radiculopathy asociated and no red flags. * Back pain related pain bigger than 4 in VAS. * Patients with no severe illnesses or conditions that would be inappropriate to enroll in this study or patients with no chronic pain. * Signed informed consent. Exclusion Criteria: * Pregnant women or breastfeeding. * Hyper acute back pain that requires emergency hospitalization. * Chronic back pain or complicated (red flags). * Patients that have received previous analgesic therapy of long half life, like corticoids, for current back pain or other pathology (inhalers are excluded). * Associated neuromuscular diseases, inflammatory diseases in the spine (Musculoskeletal Disorders 2017, 18; 454: 2-12), inability to stand up, tumoral diseases, terminal disease. * Ongoing local treatment with calcium antagonists or trinitroglycerin. * Treatment with anti-vitamins K or another anticoagulant. * Patients with adverse psychosomatic, work or social factors. * Known or suspected allergy to any component of the study drug. * Current participation in another clinical study or 30 days prior to enrollment. * Another condition that in the opinion of the PI prevents participation in the study (physical or mental) or that cannot attend controls or answer the patient's survey / diary.