The purpose of this study is to evaluate the non-inferiority clinical efficacy of two different drugs in the treatment of patients diagnosed with moderate to severe back pain treatment.

• double-blind, double-dummy, non-inferiority, prospective, parallel group, intent to treat trial.
• Experiment duration: 04 days.
• 03 visits (days 0, 2 and 4).
• Efficacy will be evaluated for back pain relief based on visual analogic scale.
• Adverse events evaluation.

Inclusion Criteria:

• Consent of the patient or legal guardian.
• Men or women aged between 18 and 65.
• Diagnosis of acute low back pain with moderate to severe pain (Visual Analogic score greater than 4 cm)

Exclusion Criteria:

• fracture confirmed by X-ray
• Diagnosis of infection, fever,
• Pregnancy, lactation;
• Diagnosis of fibromyalgia;
• Hypersensitivity to ketorolac tromethamine, any of the ingredients of the formula or other Nonsteroidal anti-inflammatory