Pirbuterol is a short-acting, beta-adrenergic receptor agonist with bronchodilator activity. Pirbuterol selectively binds to beta-2 adrenergic receptors in bronchial smooth muscle, thereby activating intracellular adenyl cyclase, an enzyme that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic-3′,5′-adenosine monophosphate (cAMP). Increased cAMP levels cause relaxation of the bronchial smooth muscle, relieve bronchospasms, improve mucociliary clearance and inhibit the release of mediators of immediate hypersensitivity from cells, especially from mast cells.
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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%.
Mechanism of Action of Pirbuterol
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).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%. 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.
Indications of Pirbuterol
- Bronchospasm
- Asthma,
- Asthma, acute
- Bronchiectasis
- Bronchospasm Prophylaxis
- Bronchial asthma,
- Chronic bronchitis,
- Chronic bronchopulmonary disorders
- Levosalbutamol’s bronchodilator properties give it indications in the treatment of COPD (chronic obstructive pulmonary disease, also known as chronic obstructive lung disease) and asthma.
- Prevention and reversal of bronchospasm in patients 12 years of age and older with reversible bronchospasm including asthma.
Contra-Indications of Pirbuterol
- Overactive thyroid gland
- Diabetes
- Ketoacidosis
- Excess Body Acid
- Low amount of potassium in the blood
- High blood pressure
- Diminished blood flow through arteries of the Heart
- Prolonged QT interval on EKG
- Abnormal heart rhythm
- Abnormal EKG with QT changes from Birth
- Kidney disease with the reduction in kidney function
- Seizures
- Paradoxical bronchospasm
- Allergies to Beta-Adrenergic Agents
Dosage of Pirbuterol
Strengths: 400 mcg or 0.4 mg
Asthma – Acute
- 2 puffs (0.4 mg) orally repeated every 4 to 6 hours. One puff (0.2 mg) repeated every 4 to 6 hours may be sufficient for some patients. A total daily dose of 12 inhalations should not be exceeded.
Asthma – Maintenance
- 2 puffs (0.4 mg) orally repeated every 4 to 6 hours. One puff (0.2 mg) repeated every 4 to 6 hours may be sufficient for some patients. A total daily dose of 12 inhalations should not be exceeded.
Chronic Obstructive Pulmonary Disease – Acute
- 2 puffs (0.4 mg) orally repeated every 4 to 6 hours. One puff (0.2 mg) repeated every 4 to 6 hours may be sufficient for some patients. A total daily dose of 12 inhalations should not be exceeded.
Chronic Obstructive Pulmonary Disease – Maintenance
- 2 puffs (0.4 mg) orally repeated every 4 to 6 hours. One puff (0.2 mg) repeated every 4 to 6 hours may be sufficient for some patients. A total daily dose of 12 inhalations should not be exceeded.
Pediatric Asthma – Acute
>=12 years
- 2 puffs (0.4 mg) orally repeated every 4 to 6 hours. One puff (0.2 mg) repeated every 4 to 6 hours may be sufficient for some patients. A total daily dose of 12 inhalations should not be exceeded.
Pediatric Asthma – Maintenance
>=12 years
- Fast heartbeat
- 2 puffs (0.4 mg) orally repeated every 4 to 6 hours. One puff (0.2 mg) repeated every 4 to 6 hours may be sufficient for some patients. A total daily dose of 12 inhalations should not be exceeded.
Normal dosage
- The usual dose for adults and children 12 years and older is two inhalations (400 mcg) repeated every 4-6 hours. One inhalation (200 mcg) repeated every 4-6 hours may be sufficient for some patients.
- A total daily dose of 12 inhalations should not be exceeded.
Side Effects of Pirbuterol
The most common
- Fast heartbeat
- Chest pain or tightness
- dry mouth
- trembling or shaking of the hands or feet
- stomach pain or cramping
- diarrhea
- a headache
- dizziness
- confusion
- stomach pain;
- back pain, joint or muscle pain.
- problems with your vision (including color vision);
- sudden chest pain or trouble breathing;
- pain or swelling in one or both legs;
- a migraine headache;
- pale skin, feeling light-headed or short of breath, rapid heart rate, trouble concentrating; or
- feeling like you might pass out.
More common
- Abdominal or stomach pain, discomfort, or tenderness
- chills or fever
- difficulty with moving
- a headache, severe and throbbing
- joint or back pain
- muscle aching or cramping
- muscle pains or stiffness
- chest pressure or squeezing pain in the chest
- discomfort in arms, shoulders, neck or upper back
- excessive sweating
- feeling of heaviness, pain, warmth and/or swelling in a leg or in the pelvis
- sudden tingling or coldness in an arm or leg
- sudden slow or difficult speech
- sudden drowsiness or need to sleep
- fast breathing
- sharp pain when taking a deep breath
- fast or slow heartbeat
- coughing up blood
- rust colored urine
- decreased amount of urine
Rare
- Anxiety
- change in vision
- chest pain or tightness
- confusion
- a cough
- Agitation
- arm, back, or jaw pain
- blurred vision
- chest pain or discomfort
- convulsions
- extra heartbeats
- fainting
- hallucinations
- a headache
- irritability
- lightheadedness
- mood or mental changes
- muscle pain or cramps
- muscle spasm or jerking of all extremities
- nervousness
Drug Interactions of Pirbuterol
Pirbuterol may interact with the following drugs, supplements & may change the efficacy of drugs
- antihistamines (e.g, cetirizine, doxylamine, diphenhydramine, hydroxyzine, loratadine)
- antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
- beta 2 agonists (e.g., salbutamol, formoterol, terbutaline)
- beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
- long-acting beta agonists (e.g., indacaterol, salmeterol)
- citalopram
- decongestant cold medications (e.g., phenylephrine, pseudoephedrine)
- decongestant eye drops and nose sprays (e.g., naphazoline, oxymetazoline, xylometazoline)
- diuretics (e.g., furosemide, hydrochlorothiazide)
- domperidone
- escitalopram
- ipratropium
- macrolide antibiotics (e.g., clarithromycin, erythromycin, telithromycin)
- methadone
- mirabegron
- monoamine oxidase inhibitors (MAOIs; e.g., moclobemide, phenelzine, rasagiline, selegiline, tranylcypromine)
- quinolone antibiotics (e.g., levofloxacin moxifloxacin ofloxacin)
- serotonin antagonists (anti-emetic medications; e.g., ondansetron granisetron, )
- theophyllines (e.g., aminophylline, oxtriphylline, theophylline)
- thiazide diuretics (water pills; e.g., hydrochlorothiazide, indapamide, metolazone)
- tolterodine
- topiramate
- tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
- aminophylline
- theophylline
Pregnancy Catagory of Pirbuterol
FDA Pregnancy Category C
Pregnancy
There are no good studies that have been done in humans with pirbuterol. But in animal studies, pregnant animals were given pirbuterol, and the babies did not show any medical issues related to this medication.
Lactation
It is not known if pirbuterol crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, a choice should be made whether to stop nursing or stop the use of this medication. Your doctor and you will decide if the benefits outweigh the risk of using pirbuterol.
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