MAXAIR
Clinical safety rating
cautionComprehensive clinical and safety monograph for MAXAIR (MAXAIR).
Beta-2 adrenergic receptor agonist; relaxes bronchial smooth muscle via increased intracellular cAMP.
| Metabolism | Primarily hepatic via glucuronidation and sulfate conjugation; also metabolized by catechol-O-methyltransferase (COMT). |
| Excretion | Renal excretion of unchanged drug accounts for approximately 90% of elimination; fecal excretion is minimal (<5%). |
| Half-life | 3.5–4.0 hours; clinically, this supports dosing every 4–6 hours as needed. |
| Protein binding | 55–70%, primarily to albumin. |
| Volume of Distribution | 2.0–2.5 L/kg; indicates extensive distribution into tissues. |
| Bioavailability | Inhalation: approximately 20–30% of the delivered dose reaches the systemic circulation; oral bioavailability is <1% due to first-pass metabolism. |
| Onset of Action | Inhalation: 5–15 minutes (metered-dose inhaler). |
| Duration of Action | 3–6 hours, with shorter duration in patients with severe asthma or during exacerbations. |
| Molecular Weight | 303.4 |
2 inhalations (340 mcg) via oral inhalation every 4-6 hours as needed for bronchospasm; not to exceed 12 inhalations per day.
| Dosage form | AEROSOL, METERED |
| Renal impairment | No specific dose adjustment required; medication is primarily hepatically metabolized. |
| Liver impairment | No specific dose adjustment guidelines; use caution in severe hepatic impairment due to potential decreased drug clearance. |
| Pediatric use | Children 6-11 years: 1-2 inhalations (170-340 mcg) via oral inhalation every 4-6 hours as needed; maximum 8 inhalations per day. Children ≥12 years: same as adult. |
| Geriatric use | No specific dose adjustment; monitor for increased sensitivity to beta-agonists (e.g., tachycardia, tremor) and concurrent diseases (e.g., cardiovascular disorders). |
| 1st trimester | Limited human data; animal studies show no teratogenic effects at clinically relevant doses. Risk cannot be excluded. |
| 2nd trimester | Use only if clearly needed; no known fetal risks from short-acting beta-agonists. Monitor for maternal tachycardia. |
| 3rd trimester | Use cautiously; may cause uterine relaxation, delay labor, or cause neonatal hypoglycemia and tachycardia. |
Clinical note
Comprehensive clinical and safety monograph for MAXAIR (MAXAIR).
| Placental transfer | Crosses placenta; extent not well quantified. Beta-agonists are known to cross. |
| Breastfeeding | Excreted in breast milk in small amounts; unlikely to cause adverse effects in nursing infants due to low oral bioavailability. Monitor for infant irritability or tachycardia. |
| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | FDA Pregnancy Category C. No adequate and well-controlled studies in pregnant women. In animal studies, maxair (pirbuterol) showed no teratogenic effects at doses up to 20 mg/kg/day in rats and up to 10 mg/kg/day in rabbits, but fetal growth retardation and increased mortality were observed at maternally toxic doses. Risk to human fetus cannot be ruled out. Use during pregnancy only if potential benefit justifies potential risk. |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and signs of bronchospasm. Fetal monitoring for heart rate and growth if used long-term in pregnancy. |
| Fertility Effects | No human data. Animal studies: no impairment of fertility in rats at oral doses up to 20 mg/kg/day. |
■ FDA Black Box Warning
No FDA boxed warning.
| Serious Effects |
Hypersensitivity to pirbuterol or any componentTachyarrhythmiasSevere coronary insufficiency
| Precautions | Paradoxical bronchospasm, Cardiovascular effects (tachycardia, arrhythmias, hypertension), Hypokalemia, Hyperglycemia, Immediate hypersensitivity reactions |
| Food/Dietary | No specific food interactions. Avoid excessive caffeine intake as it may increase stimulant effects. Grapes, grapefruit, and grapefruit juice have no significant interaction with pirbuterol. |
| Clinical Pearls | MAXAIR (pirbuterol) is a beta-2 adrenergic agonist for asthma and COPD. Use with caution in patients with cardiovascular disorders, especially coronary insufficiency, arrhythmias, or hypertension. Monitor for paradoxical bronchospasm; if occurs, discontinue immediately. Not indicated for acute severe asthma exacerbations unless patient is closely monitored. Can cause hypokalemia, especially with concomitant use of corticosteroids or diuretics. Administer with a spacer device to improve lung deposition and reduce oral side effects. |
| Patient Advice | Use only as prescribed; do not exceed recommended doses. · Rinse mouth after inhalation to prevent oral thrush. · Contact doctor if symptoms worsen or if you need more than usual doses. · Do not share the inhaler; keep it clean. · Seek immediate medical help if you experience chest pain, rapid heartbeat, or severe wheezing after use. · Inform your doctor if you have heart disease, high blood pressure, seizures, or diabetes. · Avoid using with other asthma medications without consulting your doctor. |
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