Salbutamol, Terbutaline and Bambuterol (similar to turbutaline but it is a prodrug)
SELECTIVE B2 AGONISTS
The selective B2 agonists have replaced non-selective B-agonists because they have the following advantages:
-
They induce selective effect on airway with least systemic effect, so they can be given to hypertensive patients ORAL - Preferable.
-
These agents are used to treat acute episodes of bronchial asthma and prophylactically to prevent airway obstruction.
-
The short acting selective β2 (salbutamol, terbutaline, fenoterol) can given by inhalation , orally, SC and by I.V infusion.
-
The long acting (salmeterol & formoterol) have long duration of action (12 hrs) and administrated by inhalation only.
Adverse effects:
- Tremors of skeletal muscle, nervousness and weakness.
- Tachycardia secondary to hypotension produced by skeletal vasodilatation.
- Hypokalemia
- Tolerance may occur with prolonged use but temporary cessation of drug restores its original effectiveness.
- All selective B2-agonists lose its selectivity when it is given in large frequent doses especially in aerosols.