Fishman, R. L., Kistler, C. J., Ellerbusch, M. T., Aparicio, R. T., Swami, S. S., Shirley, M. E., Jain, A. K., Fortier, L., Robertson, S., Bouchard, S. Efficacy and safety of 12 weeks of osteoarthritic pain therapy with once-daily tramadol (Tramadol Contramid OAD). 2007; 5: 273-80

PubMed ID: PM:18181382