Pentylenetetrazol

Pentylenetetrazol, also known as pentylenetetrazole, metrazol, pentetrazol (INN), pentamethylenetetrazol, Cardiazol or PTZ, is a drug formerly used as a circulatory and respiratory stimulant. High doses cause convulsions, as discovered by the Hungarian-American neurologist and psychiatrist Ladislas J. Meduna in 1934. It has been used in convulsive therapy, and was found to be effective—primarily for depression—but side-effects such as uncontrolled seizures were difficult to avoid. In 1939 pentylenetetrazol was replaced by electroconvulsive therapy, easier to administer, as the preferred method for inducing seizures in England's mental hospitals. In the US its approval by the FDA was revoked in 1982. It is used in Italy as a cough suppressant.