Clopenthixol is a thiaxanthen derivative (Fig. 1). Its full name chemically is 2-chlor-9-[3-(N-B-hydroxyathylpiperazino)-propyliden]-thioxanthen. Numerous uncontrolled trials to date (2, 3, 4, 5, 6, 7) have reported success with this drug in the treatment of schizophrenia, mania and other psychotic disorders.