The Chemistry of Ketanserin

Ketanserin belongs to a class of aromatic compounds called alkylphenylketones.1 As such, it has a ketone group substituted by a phenyl group and an alkyl group. Ketanserin is a weak base with a pKa = 7.5.2 It also has moderate lipophilicity, log P = 3.3 in the octanol-water system.

The Pharmacology of Ketanserin

Ketanserin is a serotonin receptor antagonist. Its existence and receptor binding profile was first reported by Leysen et al. of Janssen Pharmaceutica Research in 1981.3 Also, ketanserin in a potent antagonist of the histamine H1 receptor.4

Pharmacokinetic studies indicate that orally administered ketanserin is quickly and almost completely (>98%) absorbed by the body (see review in Persson et al).2 Peak plasma concentrations are achieved in 0.5 to 2 hours. In the blood, only about 5% of ketanserin remains free, while the rest binds to proteins in the plasma, primarily albumin. Less than 2% of ketanserin is excreted in the unchanged form. The compound is extensively metabolized, mostly by ketone reduction, creating ketanserin-ol which is excreted in the urine. Some of this metabolite is reoxidized in the body back to ketanserin.

The Applications and Potential of Ketanserin

Ketanserin is indicated for the treatment of hypertension. The mechanism of its hypotensive action via the blockade of α1-adrenoceptors was discovered by Fozard in 1982.5

Due to its antagonist capabilities, ketanserin is also used extensively to study the serotonin 5-HT2 receptor family. For example, in 2017, Preller et al. used ketanserin to block the 5-HT2A receptor for studying the subjective effects of LSD.6

  1. Ketanserin. DrugBank. Accessed May 18, 2020.
  2. Persson B, Heykants J, Hedner T. Clinical Pharmacokinetics of Ketanserin. Clin Pharmacokinet. 1991;20(4):263-279. doi:10.2165/00003088-199120040-00002
  3. Leysen JE, Awouters F, Kennis L, Laduron PM, Vandenberk J, Janssen PAJ. Receptor binding profile of R 41 468, A novel antagonist at 5-HT2 receptors. Life Sciences. 1981;28(9):1015-1022. doi:10.1016/0024-3205(81)90747-5
  4. Ghoneim OM, Legere JA, Golbraikh A, Tropsha A, Booth RG. Novel ligands for the human histamine H1 receptor: Synthesis, pharmacology, and comparative molecular field analysis studies of 2-dimethylamino-5-(6)-phenyl-1,2,3,4-tetrahydronaphthalenes. Bioorganic & Medicinal Chemistry. 2006;14(19):6640-6658. doi:10.1016/j.bmc.2006.05.077
  5. Fozard J. Mechanism of the hypotensive effect of ketanserin. J Cardiovasc Pharmacol. 1982;4(5):829-838. doi:10.1097/00005344-198209000-00020
  6. Preller KH, Herdener M, Pokorny T, et al. The fabric of meaning and subjective effects in LSD-induced states depend on serotonin 2A receptor activation. Current Biology. 2017;27(3):451-457.