Pirbuterol

Pronunciation

(peer BYOO ter ole)


U.S. Brand Names

Maxair™ Autohaler™



Synonyms

Pirbuterol Acetate



Generic Available

No



Use

Prevention and treatment of reversible bronchospasm including asthma



Pregnancy Risk Factor

C



Lactation

Excretion in breast milk unknown



Contraindications

Hypersensitivity to pirbuterol, albuterol, or any component of the formulation



Warnings/Precautions

Optimize anti-inflammatory treatment before initiating maintenance treatment with pirbuterol. Do not use as a component of chronic therapy without an anti-inflammatory agent. Only the mildest form of asthma (Step 1 and/or exercise-induced) would not require concurrent use based upon asthma guidelines. Patient must be instructed to seek medical attention in cases where acute symptoms are not relieved or a previous level of response is diminished. The need to increase frequency of use may indicate deterioration of asthma, and treatment must not be delayed.

Use caution in patients with cardiovascular disease (arrhythmia or hypertension or CHF), convulsive disorders, diabetes, glaucoma, hyperthyroidism, or hypokalemia. Beta agonists may cause elevation in blood pressure, heart rate, and result in CNS stimulation/excitation. Beta2 agonists may increase risk of arrhythmia, increase serum glucose, or decrease serum potassium.

Do not exceed recommended dose; serious adverse events including fatalities, have been associated with excessive use of inhaled sympathomimetics. Rarely, paradoxical bronchospasm may occur with use of inhaled bronchodilating agents; this should be distinguished from inadequate response. All patients should utilize a spacer device when using a metered-dose inhaler. Safety and efficacy have not been established in children <12 years of age.

Adverse Reactions

>10%:

Central nervous system: Nervousness (7%)

Endocrine & metabolic: Serum glucose increased, serum potassium decreased

Neuromuscular & skeletal: Trembling (6%)

1% to 10%:

Cardiovascular: Palpitations (2%), tachycardia (1%)

Central nervous system: Headache (2%), dizziness (1%)

Gastrointestinal: Nausea (2%)

Respiratory: Cough (1%)

<1%: Abdominal pain/cramps, alopecia, anxiety, bruising, chest pain, confusion, depression, diarrhea, dry mouth, edema, flushing, glossitis, hyperkinesia, hypokalemia, hypotension, insomnia, pruritus, rash, skipped beats, smell/taste changes, sore throat, stomatitis, syncope, vomiting, weakness, numbness in extremities, weight gain

Overdosage/Toxicology

Symptoms of overdose include tachycardia, tremor, hypertension, angina, and seizures. Hypokalemia also may occur. Cardiac arrest and death may be associated with abuse of beta-agonist bronchodilators. Treatment includes immediate discontinuation and symptomatic and supportive therapies. Cautious use of beta-adrenergic blocking agents may be considered in severe cases.



Drug Interactions

Decreased effect with beta-blockers

Increased toxicity with other beta agonists, MAO inhibitors, TCAs

Stability

Store between 15°C and 30°C (59°F and 86°F).



Mechanism of Action

Pirbuterol is a beta2-adrenergic agonist with a similar structure to albuterol, specifically a pyridine ring has been substituted for the benzene ring in albuterol. The increased beta2 selectivity of pirbuterol results from the substitution of a tertiary butyl group on the nitrogen of the side chain, which additionally imparts resistance of pirbuterol to degradation by monoamine oxidase and provides a lengthened duration of action in comparison to the less selective previous beta-agonist agents.



Pharmacodynamics/Kinetics

Onset of action: Peak effect: Therapeutic: Oral: 2-3 hours with peak serum concentration of 6.2-9.8 mcg/L; Inhalation: 0.5-1 hour

Half-life elimination: 2-3 hours

Metabolism: Hepatic

Excretion: Urine (10% as unchanged drug)

Dosage

Children 12 years and Adults: 2 inhalations every 4-6 hours for prevention; two inhalations at an interval of at least 1-3 minutes, followed by a third inhalation in treatment of bronchospasm, not to exceed 12 inhalations/day



Administration

Inhalation: Shake inhaler well before use.



Monitoring Parameters

Respiratory rate; FEV1, peak flow, and/or other pulmonary function tests; blood pressure, heart rate; CNS stimulation; serum glucose, serum potassium



Patient Education

Use exactly as directed (see Administration below). Do not use more often than recommended. Maintain adequate hydration (2-3 L/day of fluids) unless instructed to restrict fluid intake. You may experience nervousness, dizziness, or fatigue (use caution when driving or engaging in tasks requiring alertness until response to drug is known); or dry mouth or stomach upset (small, frequent meals, frequent mouth care, chewing gum, or sucking hard candy may help). If you have diabetes, check blood sugar; blood glucose levels may be increased. Report unresolved GI upset; dizziness or fatigue; vision changes; chest pain, rapid heartbeat, or palpitations; nervousness or insomnia; muscle cramping or tremor; or unusual cough. Inform prescriber if you are or intend to become pregnant. Consult prescriber if breast-feeding.

Pregnancy/breast-feeding precautions:

Aerosol: Store canister upside down; do not freeze. Shake canister before using. Sit when using medication. Close eyes when administering pirbuterol to avoid spray getting into eyes. Exhale slowly and completely through nose; inhale deeply through mouth while administering aerosol. Hold breath for 5-10 seconds after inhalation. Wait at least 1 full minute between inhalations. Wash mouthpiece between use. If more than one inhalation medication is used, use bronchodilator first and wait 5 minutes between medications.

Maxair™ Autohaler™: Hold upright. Raise lever so that it stays up and snaps into place. Shake well. Exhale. Seal lips tightly around mouthpiece, inhale deeply. A "click" will be heard and you will feel a soft puff when the medication has been triggered. Continue to take a full, deep breath. Remove inhaler from mouth, hold breath for 10 seconds, then exhale slowly. Note: A test-fire slide has been added to the bottom of the Autohaler™ actuator/mouthpiece. The inhaler should be primed prior to using for the first time or if it has not been used in 48 hours. To prime, remove mouthpiece; point mouthpiece away from yourself or others, and push the lever so that it stays up. Push the white test-fire slide located on the bottom of the mouthpiece to release the priming spray. In order to release a second priming spray, push lever to "down" position, then repeat steps. When two priming sprays have been done, return lever to "down" position.

Cardiovascular Considerations

Beta agonists will induce increases in heart rate. This should be considered in patients with resting tachycardia. Because of the frequent coexistence of chronic obstructive lung disease and coronary artery disease, many patients are on simultaneous therapy with beta agonists and beta-blockade. This combination should, for obvious reasons, be avoided. Frequent use of inhaled beta agonists when used in patients with atrial fibrillation, may counteract pharmacologic interventions directed at rate control. Acute inhaled beta agonists may be used to treat hyperkalemia in patients with renal failure.



Dental Health: Effects on Dental Treatment

Key adverse event(s) related to dental treatment: Xerostomia (normal salivary flow resumes upon discontinuation).



Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions



Mental Health: Effects on Mental Status

Nervousness and restlessness are common; may cause dizziness; may rarely cause insomnia



Mental Health: Effects on Psychiatric Treatment

Concurrent use with TCAs and MAO inhibitors may results in increased toxicity; monitor



Dosage Forms

Aerosol for oral inhalation, as acetate:

Maxair™ Autohaler™: 14 g [400 inhalations; contains chlorofluorocarbons]

References

National Asthma Education and Prevention Program, "Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma," Bethesda, MD, National Institutes of Health, 1997. NIH publication 97-4051.

National Asthma Education and Prevention Program, "Expert Panel Report: Guidelines for the Diagnosis and Management of Asthma Update on Selected Topics - 2002,"J Allergy Clin Immunol, 2002, 110(5 Suppl):141-219.

International Brand Names

Spirolair® (BE, LU)



Review Date: 1969-12-31 Reviewed By: Keywords: ,
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