Salbutamol-G Mechanism of Action

Pharmacology: Pharmacodynamics: Salbutamol is a selective β₂ adrenoceptor agonist. At therapeutic doses it acts on the β₂ adrenoceptors of bronchial muscle, with little or no action on β₁ adrenoceptors of cardiac muscle. It is suitable for the management and prevention of attack in asthma.
Guaiphenesin has an expectorant action which increase the output of respiratory tract fluid by reducing adhesiveness and surface tension. The increased flow or less viscid secretion promotes ciliary action and facilitate the removal of mucus. This changes a dry, unproductive cough to a cough that is more productive and less frequent.
Pharmacokinetics: Salbutamol: The majority of a dose of salbutamol given intravenously, orally or by inhalation is excreted within 72 hours. Salbutamol is bound to plasma proteins to the extent of 10%.
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%.
Guaiphenesin: Guaiphenesin is absorbed from the gastrointestinal tract. It is metabolized and excreted in the urine.