Efficacy and Safety of Fixed-dose Combination of Etoricoxib/Tramadol vs Acetaminophen/Tramadol for Acute Low Back Pain

Inclusion Criteria:

• Any sex.
• That the subject agree to participate in the study and give informed consent inwriting.
• Age> 18 years and ≤ 60 years of age at the beginning of the study.
• Diagnosis of acute low back pain as a first-time episode or after another episode,maximum 6 months before and lasting no more than 6 weeks.
• Patient with low back pain reported as moderate to severe intensity (VAS> 4 cm).
• Women of childbearing age who have an acceptable contraceptive method (eg barrier,oral hormonal, injectable, subdermal).

Exclusion Criteria:

• Patients in whom the study drug is contraindicated for medical reasons.
• Patients with an allergy or hypersensitivity to the active principle, study drugs,related products or excipients.
• Positive pregnancy test, women who are pregnant, breastfeeding or planning a pregnancywhile conducting the study.
• A significant history of gastrointestinal disorders (for example: Gastric ulcer,Crohn's disease, Ulcerative Colitis, etc.).
• Previous treatment with opioids and / or NSAIDs (Non-Steroidal Anti-InflammatoryDrugs) reported in the medical history in the last 72 hours at study entry.
• Patients with a history of alcohol or drug abuse in the last year according to DSM-V (Diagnostic and Statistical Manual of Mental Disorders).
• Patients who are receiving monoamine oxidase inhibitors (MAOIs) or who have receivedthem within the past 2 weeks.
• Patients with a history of established ischemic heart disease, peripheral arterialdisease and / or cerebrovascular disease (including patients who have recentlyundergone coronary artery bypass grafting or angioplasty).
• Patients with status epileptic seizure disorders and grand mal seizures.
• Patients with a history of severe acute or chronic liver failure.
• Patients with a history of moderate to severe renal failure.
• Patient with a history of chronic pain (eg, fibromyalgia, Paget's disease, bone paininduced by metastatic cancer).
• Low back pain due to major trauma (eg vertebral fracture, post-traumaticspondylolisthesis), or due to a visceral disorder (eg dysmenorrhea, endometriosis).
• At medical criteria, a disease that affects the prognosis and prevents outpatientmanagement, for example, but not restricted to: intestinal obstruction, paralyticileus, end-stage cancer, kidney, heart, respiratory or liver failure or mental illnessor with surgical procedures or scheduled hospitals.
• History / presence of any disease or condition that, in the Investigator's opinion,could pose a risk to the patient or confuse the efficacy and safety of the studyresults. ----Patients with symptoms suggesting an active COVID-19 infection (i.e.,fever, cough, dyspnea) and / or contact in the past 14 days with a suspected orpositive COVID-19 patient.
• Oncological patients (except basal cell skin cancer) or with serious diseases that, inthe opinion of the investigator, have a serious prognosis or a life expectancy of lessthan 1 year, as well as mental illnesses.
• The patient is participating in another clinical study involving an investigationaltreatment or participated in one in the previous 4 weeks.
• Patients whose participation in the study may be influenced (employment relationshipwith the research center or sponsor, inmates, etc.).