Phase III, multicenter, prospective, randomized, double-blind, parallel-group study to evaluate the efficacy and safety of a fixed-dose combination of etoricoxib/betamethasone compared with etoricoxib alone in patients with an acute episode of bursitis, tendinitis, or synovitis affecting the shoulder, elbow, knee, or ankle.

This is a Phase III, multicenter, prospective, randomized, double-blind, parallel-group study to compare the efficacy and safety of a fixed-dose combination of etoricoxib/betamethasone versus etoricoxib alone in patients with an acute episode of bursitis, tendinitis, or synovitis of the shoulder, elbow, knee, or ankle. Eligible participants will be randomized to receive either etoricoxib/betamethasone 90 mg/0.25 mg once daily for 14 days (Group A) or etoricoxib 90 mg once daily for 14 days (Group B). The study includes three visits (Day 1 baseline, Day 7 ± 2, Day 14 ± 2) and two follow-up calls (Day 3 ± 2 and Day 10 ± 2); investigators will collect medical history, perform physical examinations focused on the affected region, and review laboratory and diagnostic assessments as applicable. Pain intensity in the affected joint will be assessed using a Visual Analog Scale (VAS) during active movement and at rest at each visit/call, and daily by patients in a trained Patient Diary completed in the afternoon at the same time each day. Outcomes include changes from baseline in maximum pain (movement and rest) over 14 days, clinical improvement at Days 7 and 14 using the Clinical Global Impression scale, patient and investigator global assessments, and safety based on adverse events summarized by treatment group; rescue medication use (paracetamol 500 mg) and treatment adherence will also be evaluated.

Inclusion Criteria:

• Patients willing and able to participate in the study and provide written informed consent.
• Male or female.
• Age ≥ 18 years at study entry.
• Women of childbearing potential who use an acceptable contraceptive method (barrier, oral hormonal, injectable, subdermal), or women who are naturally postmenopausal or surgically sterile.
• Clinical diagnosis of an acute episode of tendinitis, bursitis, or synovitis of the shoulder, elbow, knee, or ankle, with onset within 7 days prior to the first dose of study medication.
• A score ≥ 40 mm on a 100-mm Visual Analog Scale (VAS) for maximum pain intensity during active movement, as reported by the patient at the time of study inclusion.
• In the opinion of the Principal Investigator or treating physician, the participant is an appropriate candidate for treatment with the investigational product.

Exclusion Criteria:

• Participation in another clinical study involving an investigational treatment, or participation in such a study within 4 weeks prior to study start.
• Patients whose participation could be influenced (e.g., employment relationship with the study site or sponsor, vulnerable populations, etc.).
• In the investigator's medical judgment, any disease that affects prognosis and prevents outpatient management, including but not limited to: terminal cancer, renal, cardiac, respiratory, or hepatic failure, mental illness, or scheduled surgical procedures or hospitalizations.
• History or presence of any disease or condition that, in the investigator's opinion, could pose a risk to the patient or confound the efficacy and safety evaluation of the investigational product, such as significant degenerative disease or an infectious process in the joints of interest.
• Fever: axillary temperature > 37.5°C within 2 days prior to or at the time of study inclusion.-
• Pregnant or breastfeeding patients.
• Contraindication to the study medications.
• History of allergic reaction to NSAIDs (non-steroidal anti-inflammatory drugs), paracetamol (acetaminophen), or known hypersensitivity to the study medications.
• Significant history of gastrointestinal disorders (e.g., gastric ulcer, Crohn's disease, ulcerative colitis, gastrointestinal bleeding, etc.).
• History of congestive heart failure (NYHA Class II-IV), established ischemic heart disease, peripheral arterial disease and/or cerebrovascular disease (including patients who have recently undergone coronary revascularization procedures or angioplasty).
• Treatment with corticosteroids within 1 month prior to study start.
• Treatment with NSAIDs within 48 hours prior to study start, except for cardioprotective-dose aspirin.
• Tendinitis or bursitis secondary to a systemic inflammatory disease, or synovitis secondary to hemophilia.
• History of harmful alcohol and/or drug use causing adverse health and social effects.
• Clinical suspicion of joint infection or another joint disease other than tendinitis, bursitis, or synovitis.
• History of chronic hepatic impairment (Child-Pugh A, B, and/or C).
• History of acute renal failure or chronic kidney disease (glomerular filtration rate < 30 mL/min/1.73 m²).
• Significant history of known coagulation disorders (e.g., von Willebrand disease, hemophilia, vitamin K deficiency, etc.) or use of anticoagulants.
• Oncology patients (except basal cell skin cancer or patients with cancer in remission) or patients with severe diseases that, in the investigator's opinion, have a poor prognosis or a life expectancy of less than 1 year, as well as mental illnesses.