The primary objective of this study is to assess the reduction of systemic inflammation as measured by serum levels of C-reactive protein (CRP).

The secondary objectives are:

• to assess the reduction of systemic inflammation as measured changes in acute phase protein, serum amyloid A (SAA) and cytokine interleukin-6 (IL-6), and clinical American College of Rheumatology response rate, and morning stiffness duration;
• to assess the effect on pain relief within first 14 days;
• to obtain evidence of the safety and tolerability of SSR150106;
• to document trough plasma levels of SSR150106 and its first metabolite.

Inclusion Criteria:

• Either treatment-naïve patients, or those who have discontinued their Rheumatoid Arthritis-directed medication due to intolerability or insufficient efficacy
• At least 9 out of 68 tender joints; 6 out of 66 swollen joints; morning stiffness 45 min
• C-Reactive Protein >=1.8 mg/dl confirmed during screening period
• Non-poor Cytochrome P2D6 metabolizer status

Exclusion Criteria:

• Functional Rheumatoid Arthritis class IV
• Fever
• Infections with hepatitis B, or C, or HIV
• Presence or history (<5 years) of cancer
• Manifest or latent tuberculosis
• Functional abnormalities (including laboratory values) judged as clinically relevant

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.