"Anxiety drug" covers a very large field. Antileptics, beta blockers, benzodiazepines,and MAOI, SNRI, SSRI and Tricyclic class antidepressants. I am unaware of any toxic metabolites for these medications. OTOH, there are some over-the-counter supplements that have or have the potential to cause harm, including 5-HTP, L-Tryptophan and Kava.
Ian
Posted by S.A