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Clinical data
Routes of
ATC code
  • none
Legal status
Legal status
  • In general: ℞ (Prescription only)
Synonyms MER-17, MDL-4,829
CAS Number
PubChem CID
ECHA InfoCard 100.003.720
Chemical and physical data
Formula C18H21NO
Molar mass 267.37 g/mol
3D model (Jmol)
 NYesY (what is this?)  (verify)

Azacyclonol (trade names Ataractan, Calmeran, Frenoton, Frenquel, Psychosan), also known as γ-pipradrol, is a drug which is an ataractive; an agent which diminishes hallucinations in psychotic individuals.[1][2] It has also been called a tranquilizer and antipsychotic, though these definitions are not accurate as it does not actually possess such properties. Despite being a positional isomer of pipradrol, it is not a psychostimulant, and instead has mild depressant effects.[1][3]

The drug was introduced in Europe in the mid-1950s for the treatment of schizophrenia likely because it was found to attenuate the subjective psychedelic effects of LSD and mescaline in humans.[1][4] However, due to poor and mixed clinical effectiveness[4] it never gained widespread acceptance and was eventually discontinued.

The antihistamine agent terfenadine produces azacyclonol as an active major metabolite.[5]

It is made by the organometallic addition of 4-bromopyridine to benzophenone, followed by catalytic hydrogenation of the pyridine heteroaromatic ring system to the corresponding piperidine.[6]


  1. ^ a b c BRAUN DL, BROWN BB, FELDMAN RG (October 1956). "The pharmacologic activity of alpha-(4-piperidyl)-benzhydrol hydrochloride (azacyclonol hydrochloride); an ataractive agent". The Journal of Pharmacology and Experimental Therapeutics. 118 (2): 153–61. PMID 13368052. 
  2. ^ Swiss Pharmaceutical Society (2000). Index Nominum 2000: International Drug Directory (Book with CD-ROM). Boca Raton: Medpharm Scientific Publishers. ISBN 3-88763-075-0. 
  3. ^ FARRANT J (June 1963). "Interactions between cocaine, tyramine and noradrenaline at the noradrenaline store". British Journal of Pharmacology and Chemotherapy. 20 (3): 540–9. PMC 1703814Freely accessible. PMID 13944436. doi:10.1111/j.1476-5381.1963.tb01491.x. 
  4. ^ a b FORSTER W, HENDERSON AL (January 1957). "A clinical study of Frenquel (alpha (4-piperidyl) benzhydrol hydrochloride) in chronic schizophrenia". Canadian Medical Association Journal. 76 (2): 97–101. PMC 1823487Freely accessible. PMID 13383414. 
  5. ^ Martens J (April 1996). "Determination of the terfenadine metabolite azacyclonol in human serum using gas chromatography-mass spectrometry". Journal of Chromatography B. 678 (2): 349–53. PMID 8738042. doi:10.1016/0378-4347(95)00561-7. 
  6. ^ Campen Jr Marcus G Van, Pogge Raymond C, Schumann Edward L; Wm S Merrell Co; U.S. Patent 2,804,422 (1957).