Trifluoperazine dihydrochloride (TFP) is an antipsychotic phenothiazine agent and a selective α1-adrenergic receptor antagonist. Trifluoperazine dihydrochloride is also a potent dopamine D2 receptor inhibitor[1][2].

Trifluoperazine Dihydrochloride is a potent dopamine D2 receptor inhibitor used as an antipsychotic and an antiemetic. Trifluoperazine inhibited in a dose-dependent manner the stimulation of glycogenolysis, gluconeogenesis, and ureogenesis due to alpha 1-adrenergic stimulation in rat hepatocytes. Trifluoperazine is much more potent at alpha 1- than at alpha 2-adrenergic receptors [1]. Trifluoperazine was not clearly different in terms of 'no substantial improvement' (n=1016, 27 RCTs, RR 1.06 CI 0.98 to 1.14) or leaving the study early (n=930, 22 RCTs, RR 1.15 CI 0.83 to 1.58). Almost identical numbers of people reported at least one adverse event (60%) in each group (n=585, 14 RCTs, RR 0.99 CI 0.87 to 1.13), although trifluoperazine was more likely to cause extrapyramidal adverse effects overall when compared to low potency antipsychotics such as chlorpromazine (n=130, 3 RCTs, RR 1.66 CI 1.03 to 2.67, NNH 6 CI 3 to 121). One small study (n=38) found no clear differences between trifluoperazine and the atypical drug, sulpiride [2].

References:
[1]. Huerta-Bahena, J., R. Villalobos-Molina, and J.A. Garcia-Sainz, Trifluoperazine and chlorpromazine antagonize alpha 1- but not alpha2- adrenergic effects. Mol Pharmacol, 1983. 23(1): p. 67-70.
[2]. Marques, L.O., M.S. Lima, and B.G. Soares, Trifluoperazine for schizophrenia. Cochrane Database Syst Rev, 2004(1): p. CD003545.