In controlled clinical trials, bisoprolol fumarate given as single daily dose has been shown to be an effective antihypertensive agent when used alone or concomitantly with thiazide diuretics see Clinical Studies. Risk of Anaphylactic Reaction: While taking beta-blockers, patients with history of severe anaphylactic reaction to variety of allergens may be more reactive to repeated challenge, either accidental, diagnostic, or therapeutic. Anesthesia and Major Surgery: If ZIAC treatment is to be continued perioperatively, particular care should be taken when anesthetic agents that depress myocardial function, such as ether, cyclopropane, and trichloroethylene, are used. To lower your risk of dizziness and lightheadedness, get up slowly when rising from sitting or lying position. The effects on systolic and diastolic blood pressure reduction of the combination of bisoprolol fumarate and hydrochlorothiazide were additive. Interference with adequate oral electrolyte desconto ziac intake will also contribute to hypokalemia.