Some medicines are known to decompose due to the influence of temperature, moisture, or light and the resulting deterioration in their quality may cause unexpected serious adverse reactions in patients. In this study, we exposed various forms of naftopidil to light and determined any changes in quality from their appearance, TLC and 1H-NMR spectrum. The results showed that the degree of decomposition depended on the form of the drug, the wavelength of the light and duration of exposure to light.
