In subjects with creatinine clearance less than 40 ml/min, the plasma half-life is increased approximately threefold compared to healthy subjects.

In patients with liver cirrhosis, the rate of elimination of bisoprolol is more variable and significantly slower than that in healthy subjects, with a plasma half-life ranging from 8 to 22 hours.

In elderly subjects, mean plasma concentrations at steady state are increased, in party attributed to lower creatinine clearance. However, no significant differences in the degree of bisoprolol accumulation is found between young and elderly populations.

Hydrochlorothiazide: Hydrochlorothiazide is well absorbed (65%-75%) following oral administration. Absorption of hydrochlorothiazide is reduced in patients with congestive heart failure.

Peak plasma concentrations are observed within 1-5 hours of dosing, and range from 70-490 ng/ml following oral doses of 12.5-100 mg. Plasma concentrations are linearly related to the administered dose. Concentrations of hydrochlorothiazide are 1.6-1.8 times higher in whole blood than in plasma. Binding to serum proteins has been reported to be approximately 40% to 68%. The plasma elimination half-life has been reported to be 6-15 hours. Hydrochlorothiazide is eliminated primarily by renal pathways. Following oral doses of 12.5-100 mg, 55%-77% of the administered dose appears in urine and greater than 95% of the absorbed dose is excreted in urine as unchanged drug. Plasma concentrations of hydrochlorothiazide are increased and the elimination half-life is prolonged in patients with renal disease.

Pharmacodynamics

Bisoprolol Fumarate: Findings in clinical hemodynamics studies with bisoprolol fumarate are similar to those observed with other beta-blockers. The most prominent effect is the negative chronotropic effect, giving a reduction in resting and exercise heart rate. There is a fall in resting and exercise cardiac output with little observed change in stroke volume, and only a small increase in right atrial pressure, of pulmonary capillary wedge pressure at rest or during exercise.

In normal volunteers, bisoprolol fumarate therapy resulted in a reduction of exercise- and isoproterenol-induced tachycardia.The maximal effect occurred within 1-4 hours post-dosing. Effects generally persisted for 24 hours at doses of 5 ml or greater.

In controlled clinical trials, bisoprolol fumarate given as a single daily dose has been shown to be an effective antihypertensive agent when used alone or concomitantly with thiazide diuretics (see CLINICAL STUDIES).

The mechanism of bisoprolol fumarate's antihypertensive effect has not been completely established. Factors that may be involved include:

1) Decreased cardiac output,

2) Inhibition of renin release by the kidneys,

3) Diminution of tonic sympathetic outflow from vasomotor centers in the brain.

Beta₁ selectivity of bisoprolol fumarate has been demonstrated in both animal and human studies. No effects at therapeutic doses on beta₂-adrenoreceptor density have been observed. Pulmonary function studies have been conducted in healthy volunteers, asthmatics, and patients with chronic obstructive pulmonary disease (COPD). Doses of bisoprolol fumarate ranged from 5 to 60 mg, atenolol from 50 to 200 mg, metoprolol from 100 to 200 mg, and propranolol from 40 to 80 mg. In some studies, slight, asymptomatic increases in airway resistance (AWR) and decreases in forced expiratory volume (FEV₁) were observed with doses of bisoprolol fumarate 20 mg and higher, similar to the small increases in AWR noted with other cardioselective beta-blocking agents. The changes induced by beta-blockade with all agents were reversed by bronchodilator therapy.

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