indication

For the prevention and reversal of bronchospasm in patients 12 years of age and older with reversible bronchospasm including asthma.

pharmacology

Pirbuterol is a beta-2 adrenergic bronchodilator. In vitro studies and in vivo pharmacologic studies have demonstrated that pirbuterol has a preferential effect on beta-2 adrenergic receptors compared with isoproterenol. While it is recognized that beta-2 adrenergic receptors are the predominant receptors in bronchial smooth muscle, data indicate that there is a population of beta-2 receptors in the human heart, existing in a concentration between 10-50%. The precise function of these receptors has not been established.

mechanism of action

The pharmacologic effects of beta adrenergic agonist drugs, including pirbuterol, are at least in proof attributable to stimulation through beta adrenergic receptors of intracellular adenyl cyclase, the enzyme which catalyzes the conversion of adenosine triphosphate (AlP) to cyclic-3† ,5†-adenosine monophosphate (c-AMP). Increased c-AMP levels are associated with relaxation of bronchial smooth muscle and inhibition of release of mediators of immediate hypersensitivity from cells, especially from mast cells.

toxicity

As with all sympathomimetic aerosol medication, cardiac arrest and even death may be associated with abuse of pirbuterol.

half life

The plasma half-life measured after oral administration is about two hours.

drug interactions

Acebutolol: Antagonism

Amitriptyline: The tricyclic antidepressant, amitriptyline, increases the sympathomimetic effect of pirbuterol.

Amoxapine: The tricyclic antidepressant, amoxapine, increases the sympathomimetic effect of pirbuterol.

Atenolol: Antagonism

Bisoprolol: Antagonism

Carvedilol: Antagonism

Clomipramine: The tricyclic antidepressant, clomipramine, increases the sympathomimetic effect of pirbuterol.

Desipramine: The tricyclic antidepressant, desipramine, increases the sympathomimetic effect of pirbuterol.

Doxepin: The tricyclic antidepressant, doxepin, increases the sympathomimetic effect of pirbuterol.

Esmolol: Antagonism

Imipramine: The tricyclic antidepressant, imipramine, increases the sympathomimetic effect of pirbuterol.

Isocarboxazid: Increased arterial pressure

Labetalol: Antagonism

Linezolid: Possible increase of arterial pressure

Methyldopa: Increased arterial pressure

Metoprolol: Antagonism

Midodrine: Increased arterial pressure

Moclobemide: Moclobemide increases the sympathomimetic effect of pirbuterol.

Nadolol: Antagonism

Nortriptyline: The tricyclic antidepressant, nortriptyline, increases the sympathomimetic effect of pirbuterol.

Oxprenolol: Antagonism

Phenelzine: Increased arterial pressure

Pindolol: Antagonism

Propranolol: Antagonism

Rasagiline: Increased arterial pressure

Reserpine: Increased arterial pressure

Timolol: Antagonism