Vasoten Mechanism of Action

Pharmacology: Pharmacodynamics: Bisoprolol is a beta1-selective adrenergic blocking agent. The drug does not exhibit the intrinsic sympathomimetic activity seen with pindolol or the membrane-stabilizing activity possessed by propranolol or pindolol. At low dosages, bisoprolol selectively inhibits response to adrenergic stimuli by competitively blocking cardiac beta1-adrenergic receptors, while having little effect on the beta2-adrenergic receptors of bronchial and vascular smooth muscle. At high doses (e.g., 20mg or higher), the selectivity of bisoprolol on beta1- and beta2-adrenergic receptors usually diminishes, and the drug will competitively inhibit and adrenergic receptors.
Pharmacokinetics: Bisoprolol is absorbed almost completely from the gastrointestinal tract. Together with the very small first pass effect in the liver, this results in a high bioavailability of approximately 90%. The drug is cleared equally by the liver and kidneys.
The long plasma half-life (9-12 hours) provides 24-hour efficacy following a once daily dosage. About 95% of the drug substance is excreted through the kidneys, 50% of a dose as unchanged bisoprolol. There are no active metabolites in man.
There are limited data in children and an appropriate dosing regimen has not been established. Therefore, bisoprolol fumarate cannot be recommended for use in children.
The pharmacokinetics of bisoprolol fumarate in the pediatric population were examined in three independent studies and showed that the half-life of bisoprolol fumarate ranged from 3.6 hours and 14 hours and the clearance ranged from 0.12 L/hr/kg to 0.44 L/hr/kg. In adults, the half-life of bisoprolol fumarate ranged from 9 hours to 12 hours and the clearance ranged from 0.14 L/hr/kg to 0.15 L/hr/kg.