hp-505 hp-505 hp-505 is a triple reuptake inhibitor that was investigated by hoechst-roussel pharmaceuticals. in mice, hp-505 was a potent inhibitor of tetrabenazine-induced ptosis which may indicate antidepressant activity. hp-505identifiers iupac name 3-phenyl-3h-spiro cas number59142-94-8pubchem cid191510chemspider166303chemblchembl436281comptox dashboard (epa)dtxsid20974577 chemical and physical dataformulac18h19nomolar mass265.356 g·mol−13d model (jsmol)interactive image smiles c1(c2oc3(ccncc3)c4=c2c=cc=c4)=cc=cc=c1 inchi inchi=1s/c18h19no/c1-2-6-14(7-3-1)17-15-8-4-5-9-16(15)18(20-17)10-12-19-13-11-18/h1-9,17,19h,10-13h2key:zfjqwomhwfylpd-uhfffaoysa-n pharmacology hp-505 ic50 (µm) 5-htnedane:5-htda:5-ht 0.19 ± 0.040.34 ± 0.10.66 ± 0.151.83.5 the inhibitory effect of hp-505 on serotonin reuptake is approximately 1.8 and 3.5 times stronger than on norepinephrine and dopamine, respectively. subsequent investigations have found that hp-505 acts on presynaptic dopamine transporters and is devoid of anticholinergic effects. synthesis the n-methylated analog is called hp-365 . an older synthesis is available, although more modern methods exist now: hp-365 patent: