UV photodegradation of desipramine (DMI) was studied under different environmental variables (pH, temperature, and initial drug concentration) to investigate their effect on the mineralization rate as well as the rate and/or type of the formed phototransformation products (PTPs). The biodegradability of DMI and its PTPs was also studied using two standardized OECD tests.
LC-MS and dissolved organic carbon results for all test setups indicated that DMI was primary eliminated but not completely mineralized. 7 newly formed PTPs were identified and compared. The reaction rate was inversely proportional to the initial drug concentration, but it was not affected by test temperature. By increasing mediums’ pH, degradation rates decreased till pH 7; while increased again at pH 9. Biodegradation tests revealed that DMI and its PTPs were not readily biodegradable.
These results indicate that changeable environmental conditions could have an effect on the photodegradation rate of DMI and the formation of PTPs.