MAXAIR
Clinical safety rating: caution
Comprehensive 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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MAXAIR (MAXAIR).
| Breastfeeding | Unknown if pirbuterol is excreted in human milk. Due to lack of data and potential for serious adverse reactions in nursing infants, caution is advised. M/P ratio not determined. |
| 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. |
■ FDA Black Box Warning
No FDA boxed warning.
| Serious Effects |
["Hypersensitivity to pirbuterol or any component","Pre-existing cardiac arrhythmias (e.g., tachyarrhythmias)"]
| Precautions | ["Paradoxical bronchospasm","Cardiovascular effects (tachycardia, arrhythmias, hypertension)","Hypokalemia","Hyperglycemia","Immediate hypersensitivity reactions"] |
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| 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. |