Biochem/physiol Actions 3-Tropanylindole-3-carboxylate hydrochloride is a selective 5-HT3 serotonin receptor antagonist. Tropisetron a selective serotonin 5-HT3 receptor antagonist is used mainly as an antiemetic to treat nausea and vomiting following chemotherapy . In the treatment of fibromyalgia syndrome (FMS) tropisetron reduced not only pain perception but also had a favourable effect on cardiac dysfunction during treatment.