Complex sentence: As of 2008, few "highly" selective 5-HT 2B receptor ligands have been discovered, although numerous potent non-selective compounds are known, particularly agents with concomitant 5-HT 2C binding.
Split into simpler sentences: As of 2008, few highly selective 5-HT 2B receptor ligands have been discovered. However, numerous potent non-selective compounds are known, particularly agents with concomitant 5-HT 2C binding.