Two diethyl analogs (containing two ethyl groups in place of the two methyl groups) of psilocybin and psilocin were synthesized by Hofmann: 4-phosphoryloxy-N,N-diethyltryptamine, called CEY-19, and 4-hydroxy-N,N-diethyltryptamine, called CZ-74. Because their physiological effects last only about three and a half hours (about half as long as psilocybin), they proved more manageable in European clinics using "psycholytic therapy"—a form of psychotherapy involving the controlled use of psychedelic drugs. Sandoz marketed and sold pure psilocybin under the name Indocybin to physicians and clinicians worldwide. There were no reports of serious complications when psilocybin was used in this way.