RS-102221: a novel high affinity and selective, 5-HT2C receptor antagonist

Neuropharmacology. 1997 Apr-May;36(4-5):621-9. doi: 10.1016/s0028-3908(97)00049-x.


The 5-HT2C receptor is one of three closely related receptor subtypes in the 5-HT2 receptor family. 5-HT2A and 5-HT2B selective antagonists have been described. However, no 5-HT2C selective antagonists have yet been disclosed. As part of an effort to further explore the function of 5-HT2C receptors, we have developed a selective 5-HT2C receptor antagonist, RS-102221 (a benzenesulfonamide of 8-[5-(5-amino-2,4-dimethoxyphenyl) 5-oxopentyl]-1,3,8-triazaspiro[4.5]decane-2,4-dione). This compound exhibited nanomolar affinity for human (pKi = 8.4) and rat (pKi = 8.5) 5-HT2C receptors. The compound also demonstrated nearly 100-fold selectivity for the 5-HT2C receptor as compared to the 5-HT2A and 5-HT2B receptors. RS-102221 acted as an antagonist in a cell-based microphysiometry functional assay (pA2 = 8.1) and had no detectable intrinsic efficacy. Consistent with its action as a 5-HT2C receptor antagonist, daily dosing with RS-102221 (2 mg/kg intraperitoneal) increased food-intake and weight-gain in rats. Surprisingly, RS-102221 failed to reverse the hypolocomotion induced by the 5-HT2 receptor agonist 1-(3-chlorophenyl)piperazine (m-CPP). It is concluded that RS-102221 is the first selective, high affinity 5-HT2C receptor antagonist to be described.

MeSH terms

  • Animals
  • CHO Cells
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Cricetinae
  • Feeding Behavior / drug effects
  • Female
  • Guinea Pigs
  • Humans
  • Hydrogen / metabolism
  • Ligands
  • Male
  • Motor Activity / drug effects
  • Radioligand Assay
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Serotonin / drug effects
  • Receptors, Serotonin / metabolism*
  • Serotonin Antagonists / pharmacology*
  • Spiro Compounds / pharmacology*
  • Sulfonamides / pharmacology*
  • Weight Gain / drug effects


  • 8-(5-(5-amino-2,4-dimethoxyphenyl)-5-oxopentyl)-1,3,8-triazaspiro(4.5)decane-2,4-dione
  • Ligands
  • Receptors, Serotonin
  • Serotonin Antagonists
  • Spiro Compounds
  • Sulfonamides
  • Hydrogen