Phase III longitudinal, multicenter, randomized, double-blind clinical trial. The aim of this study is to evaluate the efficacy and safety of the Fixed-Dose Combination of Etoricoxib/Betamethasone Versus Etoricoxib in Patients With Acute Gouty Arthritis

Researchers will compare the fixed-dose combination of Etoricoxib/Betamethasone versus Etoricoxib in acute gouty arthritis by comparing the level of pain in the affected joint during the 8 days of follow up. The adverse events related to the interventions will be registered during follow up.

Participants will:

• Be randomized into one of the 2 intervention groups (A or B)
• Visit the clinic in 3 occasions (day 0, day 5 of follow up and day 8 of follow up)
• In case needed the patient could take 500 mg of acetaminophen, as a rescue medication, previous authorization of de principal investigator

Inclusion Criteria:

• Willing to participate in the study and provide written informed consent.
• Women of childbearing potential and sexually active must use an acceptable contraceptive method (barrier and/or hormonal) as determined by the investigator.
• History of hyperuricemia diagnosis (uric acid > 7 mg/dL) reported in medical history or patient interview.
• Clinical diagnosis of acute gouty arthritis with a score of at least 4 based on the following criteria: Male (2 points), history of a similar episode (2 points), symptom onset within the last 24 hours (0.5 points), joint redness (1 point), involvement of the first metatarsophalangeal joint (2.5 points), and hypertension or at least one cardiovascular disease (1.5 points).
• Acute episode characterized by severe pain, inflammation, edema, and erythema in the affected joint (≤ 48 hours before study inclusion).
• In the opinion of the Principal Investigator or treating physician, the patient is eligible for treatment with the investigational product and may benefit clinically

Exclusion Criteria:

• Patients participating in another clinical study involving an investigational treatment or participation in one within the two weeks prior to study initiation.
• Patients whose participation in the study may be influenced (e.g., employment relationship with the research center or sponsor, vulnerable populations, etc.).
• In the investigator's judgment, any condition that affects prognosis and prevents outpatient management, which must be assessed by the principal investigator to determine the patient's eligibility.
• History of severe, progressive, or unstable advanced disease of any kind that may interfere with efficacy and safety evaluations or put the patient at risk.
• Pregnant or breastfeeding patients.
• The study medication is contraindicated for medical reasons.
• History of intolerance or allergic reaction to NSAIDs (nonsteroidal anti-inflammatory drugs), paracetamol, or known hypersensitivity to any component of the formulation.
• Significant history of gastrointestinal disorders (e.g., gastric ulcer, Crohn's disease, ulcerative colitis, gastrointestinal bleeding, etc.).
• History of congestive heart failure (NYHA classification II-IV), established ischemic heart disease, peripheral arterial disease, and/or cerebrovascular disease (including patients who have recently undergone coronary revascularization or angioplasty).
• Treatment with systemic corticosteroids for the management of acute gouty arthritis within two weeks before study initiation.
• Treatment with NSAIDs within 48 hours prior to study initiation, except for aspirin at cardioprotective doses.
• History of treatment failure with selective COX-2 inhibitors, as reported in medical history or patient interview.
• Presence of acute polyarticular gout affecting more than four joints.
• History of alcohol or drug abuse within the past year.
• Clinical suspicion of joint infection or another joint disease different from acute gouty arthritis.
• History of chronic liver failure (Child-Pugh A, B, and/or C), as reported in medical history or patient interview.
• History of chronic renal failure (glomerular filtration rate <30 ml/min/1.73 m²), as reported in medical history or patient interview.
• Significant history of known coagulation disorders (e.g., Von Willebrand disease, hemophilia, vitamin K deficiency, etc.) or use of anticoagulants, as reported in medical history or patient interview.
• Oncology patients (except for basal cell skin cancer) or patients with severe diseases that, in the investigator's opinion, have a severe prognosis or a life expectancy of less than one year, as well as patients with mental illnesses.
• Patients with symptoms suggestive of active COVID-19 infection (e.g., fever, cough, shortness of breath) and/or contact within the last 14 days with a suspected or confirmed COVID-19 case.