This reduces the volume of the blood, decreasing blood return to the heart and thus cardiac output and, by other mechanisms,
is believed
to lower peripheral vascular resistance.
Hydrochlorothiazide is sold both as a generic drug and under a large number of brand names, including Apo-Hydro, Aquazide H, Dichlotride, Hydrodiuril, HydroSaluric, Microzide, Esidrex, and Oretic.
http://en.wikipedia.