To assess two regimens of thiocolchicoside injection and capsule in combination with either diclofenac or ibuprofen in patients with acute low back pain.

Inclusion Criteria:

• Diagnosis of acute low back pain of recent onset (less than 7 days) and defined by spontaneous pain intensity at rest more than or equal to 50mm of the visual analog scale.
• Presence of lumbar muscular contracture

Exclusion Criteria:

• Acute low back pain due to vertebral collapse or neoplastic, inflammatory (ankylosing spondylitis), or infective origins
• Patients with psychiatric or mental diseases, or unable to follow the requests of the protocol
• Renal failure (serum creatinine > 160 µmol/l or > 1.80 mg/dl) and/or severe hepatic dysfunction (alanine aminotransferase and/or aspartate aminotransferase and/or total bilirubin > 2 Upper normal limit).
• Positive history of cerebro-vascular accidents or myocardial infarction in the six months prior the inclusion.
• Severe heart failure.
• Myopathy / myasthenia.
• Patients treated during two days prior to inclusion with steroidal agents.
• Known or suspected hypersensitivity to thiocolchicoside.
• Known or suspected hypersensitivity to nonsteroidal anti-inflammatory drugs
• History of active peptic ulcer or gastro intestinal bleeding.
• History of nonsteroidal anti-inflammatory drugs induced allergic asthma.
• Concomitant treatment with 2-agonists (i.e. clonidine).
• Pregnant or breast feeding women.
• Females of child bearing potential, not taking adequate contraception.
• Patients with history of alcohol, drugs or narcotics abuse.
• Previous inclusion in this study or in another study in the past 6 months.