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Systematic (IUPAC) name
CAS Number 74050-98-9
ATC code C02KD01 (WHO) QD03AX90
PubChem CID 3822
Chemical data
Formula C22H22FN3O3
Molar mass 395.43 g/mol[[Script error: No such module "String".]]
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Ketanserin is drug with affinity for multiple G protein-coupled receptors (GPCR). Initially it was believed to be a highly selective antagonist for serotonin 5-HT2A receptors, however this is not true. Ketanserin only has weak selectivity for 5-HT2A receptors over 5-HT2C receptors (~20-30 fold). Ketanserin also has high affinity for alpha-1 adrenergic receptors, and very high affinity for histamine H1 receptors. Therefore, ketanserin can not be used to reliably discriminate between the effects of 5-HT2A and 5-HT2C receptors when both are present in an experimental system. Furthermore, when alpha-1 and H1 receptors are present, the effects of ketanserin can potentially represent a complex interaction of serotonin, adrenergic, and histamine receptor systems. Complicating the matter further is the fact that ketanserin has moderate affinity for alpha-2 adrenergic (~200 nM) and 5-HT6 (~300 nM) receptors as well as weak affinity for dopamine D1 and D2 receptors (~300 nM and ~500 nM respectively). Ketanserin at levels of 500 nM or greater are thus potentially affecting at least 8 different GPCRs from 4 different families. (All affinity levels taken from the NIMH Psychoactive Drug Screening Program database [1])

Receptors for which ketanserin has high affinity binding:

  • 5-HT2A = 2-3 nM (rat and human)
  • 5-HT2C = 50 nM (rat), 100 nM (human)
  • alpha-1 adrenergic = ~40 nM
  • Histamine H1 = 2 nM

Ketanserin was discovered at Janssen Pharmaceutica in 1980.



It is classified as an antihypertensive by the World Health Organization[2] and the National Institute of Health.[3]

It has been used to reverse hypertension caused by protamine (which in turn was administered to reverse the effects of heparin overdose).[4]

The reduction in hypertension is not associated with reflex tachycardia.[5]

It has been used in cardiac surgery.[6]

As a radioligand

With tritium (3H) radioactively labeled ketanserin is used as a radioligand for the serotonin 5-HT2A receptor, e.g. in receptor binding assays and autoradiography.[7] This radiolabeling enables the study of the serotonin-2A receptor distribution in the human brain.[8]

An autoradiography study of the human cerebellum has found an increasing binding of H-3-ketanserin with age (from below 50 femtomol per milligram tissue at around 30 years og age to over 100 above 75 years).[9] The same research team found no significant correlation with age in their homogenate binding study.


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  1. NIMH Psychoactive Drug Screening Program
  2. ATC/DDD Index
  3. Ketanserin
  4. van der Starre PJ, Solinas C (1996). "Ketanserin in the treatment of protamine-induced pulmonary hypertension". Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital. 23 (4): 301–4. PMC 325377Freely accessible. PMID 8969033. 
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  7. Simon B. Eickhoff, Axel Schleicher, Filip Scheperjans, Nicola Palomero-Gallagher & Karl Zilles (2007). "Analysis of neurotransmitter receptor distribution patterns in the cerebral cortex". NeuroImage. 34 (4): 1317–1330. doi:10.1016/j.neuroimage.2006.11.016. PMID 17182260. 
  8. A. Pazos, A. Probst, J. M. Palacios (1987). "Serotonin receptors in the Human Brain—IV. Autoradiographic mapping of serotonin-2 receptors". Neuroscience. 21 (1): 123–139. doi:10.1016/0306-4522(87)90327-7. PMID 3601071. 
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