bisoprolol and hydrochlorothiazide, Ziac
Omudhome Ogbru, PharmD
Omudhome Ogbru, PharmD
Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.
Medical and Pharmacy Editor:
GENERIC NAME: bisoprolol and hydrochlorothiazide
BRAND NAME: Ziac
DRUG CLASS AND MECHANISM: Ziac is a combination product containing bisoprolol (Zebeta) and hydrochlorothiazide (HCTZ). Bisoprolol is a beta-adrenergic receptor blocking agent used for treating high blood pressure and heart pain (angina). Bisoprolol prevents the neurotransmitters (chemicals that nerves use to communicate with other nerves), norepinephrine and epinephrine (adrenaline), from binding to beta adrenergic receptors on nerves. By blocking the effect of norepinephrine and epinephrine on the nerves reaching the heart and blood vessels, beta blockers reduce heart rate and the force with which the heart contracts and reduce blood pressure by dilating blood vessels. It also may constrict air passages by stimulating the muscles that surround the air passages. Hydrochlorothiazide (HCTZ) is a diuretic (water pill) used for treating high blood pressure (hypertension) and accumulation of fluid. It works by blocking salt and fluid reabsorption in the kidneys, causing increased urine output (diuresis). The mechanism of its action in lowering high blood pressure is not well understood. The combination of bisoprolol and HCTZ reduces blood pressure better than either drug alone. Ziac was approved in March 1993.
GENERIC AVAILABLE: Yes
PREPARATIONS: Tablets (bisoprolol/hydrochlorothiazide): 2.5/6.25 mg, 5/6.25 mg, and 10/6.25 mg.
STORAGE: Ziac should be stored at room temperature, 59- 86 F (15-30 C) in a tight container.
PRESCRIBED FOR: Ziac is used for treating patients with high blood pressure who have not adequately responded to either individual agent alone.
DOSING: The dose of Ziac is tailored to the patient's needs. The initial dose is 2.5/6.25 mg daily. The dose may be increased very two weeks and the maximum dose is 20/12.5 mg once daily.
DRUG INTERACTIONS: Rifampin may increase the metabolism (destruction) of bisoprolol, possibly making bisoprolol less effective. Certain calcium channel blockers (CCBs), especially verapamil (Calan, Isoptin) and diltiazem (Cardizem, Tiazac), may enhance the effect of bisoprolol on the heart. In some patients, this may cause excessive slowing of the heart rate or reduce the heart's ability to beat. The use of digoxin (Lanoxin) with bisoprolol also may cause an excessive reduction in heart rate.
Hydrochlorothiazide reduces the elimination of lithium (Lithobid, Eskalith) by the kidneys and can lead to lithium toxicity. Nonsteroidal anti-inflammatory drugs, for example, ibuprofen, may reduce the blood pressure effects of hydrochlorothiazide.
Blood sugar levels can be elevated by HCTZ, necessitating adjustment in the doses of medications that are used for treating diabetes.
Combining HCTZ with corticosteroids may increase the risk for low levels of blood potassium and other electrolytes. Low blood potassium can increase the toxicity of digoxin (Lanoxin). Cholestyramine (Questran, Questran Light) and colestipol (Colestid) bind to hydrochlorothiazide and reduce its absorption from the gastrointestinal tract by 43%-85%.
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