Ziac Dosage

Bisoprolol is an effective treatment of hypertension in once-daily doses of 2.5 to 40 mg, while hydrochlorothiazide is effective in doses of 12.5 to 50 mg. In clinical trials of bisoprolol/hydrochlorothiazide combination therapy using bisoprolol doses of 2.5 to 20 mg and hydrochlorothiazide doses of 6.25 to 25 mg, the antihypertensive effects increased with increasing doses of either component.

The adverse effects (see WARNINGS) of bisoprolol are a mixture of dose-dependent phenomena (primarily bradycardia, diarrhea, asthenia, and fatigue) and dose-independent phenomena (eg, occasional rash); those of hydrochlorothiazide are a mixture of dose-dependent phenomena (primarily hypokalemia) and dose-independent phenomena (eg, possibly pancreatitis); the dose-dependent phenomena for each being much more common than the dose-independent phenomena. The latter consist of those few that are truly idiosyncratic in nature or those that occur with such low frequency that a dose relationship may be difficult to discern. Therapy with a combination of bisoprolol and hydrochlorothiazide will be associated with both sets of dose-independent adverse effects, and to minimize these, it may be appropriate to begin combination therapy only after a patient has failed to achieve the desired effect with monotherapy. On the other hand, regimens that combine low doses of bisoprolol and hydrochlorothiazide should produce minimal dose-dependent adverse effects, eg, bradycardia, diarrhea, asthenia and fatigue, and minimal dose-dependent adverse metabolic effects, ie, decreases in serum potassium (see CLINICAL PHARMACOLOGY).