Dosing and uses of Metaproterenol
Adult dosage forms and strengths
tablet
- 10mg
- 20mg
syrup
- 10mg/5mL
Asthma, Reversible Bronchospasm
20 mg PO three/four times daily
Pediatric dosage forms and strengths
tablet
- 10mg
- 20mg
syrup
- 10mg/5mL
Asthma
PO
- <2 years old: 0.4 mg/kg PO q8-12hr
- 2-6 years old: 1-3.5 mg/kg/day divided q6-8hr PO; not to exceed 10 mg/dose
- 6-9 years old: 10 mg PO three/four times daily
- >12 years old: 20 mg PO three times daily
Metaproterenol adverse (side) effects
>10%
Tremor (2-17%)
Tachycardia (6-17%)
Nervousness (5-20%)
1-10%
Diaphoresis increased (4%)
Headache (4%)
Heartburn (4%)
Palpation (4%)
Pharyngitis (4%)
Dizziness (1-4%)
Insomnia (2%)
Weakness (1%)
Nausea (1-4%)
Exacerbation of asthma (2%)
<1%
Chest pain
Hypertension
Weakness
Syncope
Spasms
Warnings
Contraindications
Hypersensitivity
Tachycardia secondary to heart condition
Cautions
Reports of some patients who developed cramps in muscles of extremities which responded to potassium salts PO
Use caution in recent MI, myocardial insufficiency, HTN, hyperthyroidism, severe cardiovascular disorder, seizure disorders
Increases risk of hypokalemia;; use with caution
Beta2-agonists may increase serum glucose; use caution
Metered-dose inhalers that contain chlorofluorocarbons (CFCs) are currently being phased out in the United States; alternate inhalers without CFCs are available
Pregnancy and lactation
Pregnancy category: C
Lactation: Not known if excreted in breast milk, not recommended
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Metaproterenol
Mechanism of action
Beta-2 receptor agonist with some beta-1 activity; stimulation of beta2 receptors may result in bronchial smooth muscle relaxation
Pharmacokinetics
Onset: 30 min (oral)
Peak effect: 1 hr
Duration: 2-6 hr
Metabolism: Liver
Metabolites: Metaproterenol-O-sulfate
Excretion: Uurine (40%)
