RiteMED Salbutamol Mechanism of Action

Pharmacology: Pharmacodynamics: Salbutamol is a selective short-acting beta₂-adrenergic agonist with preferential effect on beta₂-adrenergic receptors in the respiratory tract. It stimulates adenyl cyclase, the enzyme which catalyzes the conversion of adenosine triphosphate (ATP) to cyclic-3',5'-adenosine monophosphate (cAMP); cAMP mediates cellular responses such as bronchial smooth muscle relaxation resulting in bronchodilation.
Pharmacokinetics: Salbutamol is readily absorbed from the gastrointestinal tract after oral administration. Salbutamol's onset of action is within 30 minutes, peaks in 2 to 3 hours and persists for 4 to 6 hours after a dose; the plasma half-life of is from 4-6 hours. It is extensively metabolized in the liver, being converted to salbutamol 4'-O-sulfate. Salbutamol and its metabolites are rapidly excreted in urine and feces. After oral administration of Salbutamol to healthy individuals, about 75% of a single dose is excreted in urine within 72 hours, mainly as the major metabolite about 4% of the dose is excreted in feces.
Animal studies show that Salbutamol can cross the blood-brain barrier and the placenta. It may be secreted in breast milk, but concentrations are not known.