Structural elucidation of two photolytic degradation products of tetrabenazine

- Tetrabenazine solutions were exposed to forced stressed conditions.
- Tetrabenazine was unstable under light experiments with strong discoloration.
- Synthesis and characterization of DTBZ and TTBZ·HCl were achieved.
- X-ray crystallography of DTBZ and TTBZ·HCl was carried out.
- DTBZ and TTBZ·HCl were the main impurities in tetrabenazine light-exposed solutions.