rn Please consult your physician before taking any medication. Generic name: Bisoprolol fumarate, Hydrochlorothiazide Brand names: Ziac (Spanish name, Biconcor) Why is Ziac prescribed? Ziac is used to treat high blood pressure. It combines a beta-blocker (bisoprolol) with a thiazide diuretic (hydrochlorothiazide). Beta-blockers decrease the force and rate of heart contractions, thus lowering blood pressure. Diuretics help your body produce and eliminate more urine, which also helps lower blood pressure. Ziac may also be used for purposes other than those listed in this medication guide.