Non inferiority, multicentric, double blind study whose the primary objective is to compare the effectiveness of two products in pain reduction. Primary endpoint: reduction in pain average at day 7 compared to day 1(baseline), using Analogue Visual Scale (AVS) for pain evaluation. Secondary endpoint: to evaluate the products safety at the gastrointestinal system.

Phase IIIb, non-inferiority, multicentric, double-blind study.Population: 160 patients, 80 in each study arm, both gender with mild to moderate lumbago, without irradiation and with muscle contraction, aged 18 (eighteen) and 65 (sixty five) years, without previous history of stomach or duodenal ulcer and gastritis.

Inclusion Criteria:

• Informed of the nature of the study and given written informed consent
• Patients with mild to moderate lumbago
• Aged between 18 and 65 years old

Exclusion Criteria:

• Known allergy or sensitivity to drug components
• Treatment with another anti inflammatory or corticoid
• Treatment with oral anticoagulants
• Treatment with oxidase monoamine 2 weeks before the study
• Treatment with methotrexate
• Stomach or duodenal ulcer and gastritis
• Dehydration
• Acute myocardial infarction or heart failure
• Hyperthyroidism
• Pregnant or lactating patients
• Treatment with lithium
• User of alcohol and barbiturates
• Hepatic or renal failure