Ventar Mechanism of Action

Pharmacology: Pharmacodynamics: Salbutamol (Ventar) is a direct-acting sympathomimetic agent with predominantly β-adrenergic activity and a selective action on β2-receptors. It is used as bronchodilator by stimulating β2-adrenergic receptors in the lungs to relax bronchial smooth muscle thereby relieving bronchospasm, increasing vital capacity, decreasing residual volume and reducing airway resistance. As a predominantly β-receptor stimulant, it has a more selective action. Its bronchodilating action being more prominent than its effect on the heart. Such β-adrenoceptor stimulants are preferred to other bronchodilator like isoprenaline for the management of asthma.
Pharmacokinetics: Tablet & Syrup: After oral administration, salbutamol is absorbed from the gastrointestinal tract and undergoes considerable first-pass metabolism to the phenolic sulphate. Both unchanged drug and conjugate are excreted primarily in the urine. The bioavailability of orally administered salbutamol is about 50%.
Nebulizing solution: When given by inhalation, 10 to 20% of the dose reaches the lower airways. The remainder is retained in the delivery system or is swallowed and absorbed from the gut. Salbutamol is rapidly excreted, mainly in the urine, as metabolites and unchanged drug; a smaller proportion is excreted in faeces.