Photostability studies on (±)-tramadol in a liquid formulation

Background Tramadol((±)-TRA) is recommended for the treatment of mild to moderate cancer painby the World Health Organization. An oral liquid formulation of (±)-TRA is preferable for patients with a compromised swallowing function. However, the stability of (±)-TRA in aqueous solutionhas yet to be determined in a clinical setting. The aim of this study was to evaluate the photostability of (±)-TRA in aqueous solutionin a clinical setting.