METAPROTERENOL SULFATE
(met-a-proe-ter'e-nole)
Alupent, Metaprel
Classifications: autonomic nervous system agent; beta-adrenergic agonist; bronchodilator
Prototype: Albuterol
Pregnancy Category: C

Availability

10 mg, 20 mg tablet; 10 mg/5 mL syrup; 75 mg, 150 mg metered dose inhaler; 0.4%, 0.6%, 5% solution for inhalation

Actions

Potent synthetic sympathomimetic amine similar to isoproterenol in chemical structure and pharmacologic actions. Acts selectively on beta2-adrenergic receptors to relax smooth muscle of bronchi, uterus, and blood vessels supplying skeletal muscles.

Therapeutic Effects

Bronchodilator; controls bronchospasm in asthmatics.

Uses

Bronchodilator in symptomatic relief of asthma and reversible bronchospasm associated with bronchitis and emphysema.

Unlabeled Uses

Treatment and prophylaxis of heart block and to avert progress of premature labor (tocolytic action).

Contraindications

Sensitivity to other sympathomimetic agents; cardiac arrhythmias associated with tachycardia; hyperthyroidism; pregnancy (category C), lactation. Safety in children <12 y (for aerosol use) is not established.

Cautious Use

Older adults; hypertension, cardiovascular disorders including coronary artery disease; hyperthyroidism; diabetes.

Route & Dosage

Bronchospasm
Adult: PO 20 mg q6–8h Metered Dose Inhaler 2–3 inhalations q3–4h (max: 12 inhalations/d) Nebulizer 5–10 inhalations of undiluted 5% solution IPPB 2.5 mL of 0.4–0.6% solution q4–6h
Geriatric: PO 10 mg 3–4 times/d, may increase to 20 mg 3–4 times/d
Child: PO <2 y, 0.4 mg/kg t.i.d.–q.i.d.; 2–6 y, 1.2–2.6 mg/kg/d in 3–4 divided doses; 6–9 y, 10 mg q6–8h; >9 y, 20 mg q6–8h

Administration

Oral
Inhalation

Adverse Effects (1%)

CNS: Nervousness, weakness, drowsiness, tremor (particularly after PO administration), headache, fatigue. CV: Tachycardia, hypertension, cardiac arrest, palpitation. GI: Nausea, vomiting, bad taste. Urogenital: Occasional difficulty in micturition and muscle cramps. Respiratory: Throat irritation, cough, exacerbation of asthma.

Interactions

Drug: Epinephrine other sympathomimetic bronchodilators may compound effects of metaproterenol; mao inhibitors, tricyclic antidepressants potentiate action of metaproterenol on vascular system; the effects of both metaproterenol and beta-adrenergic blockers are antagonized.

Pharmacokinetics

Absorption: 40% of PO doses reach systemic circulation. Onset: Inhaled: 1 min; PO 15 min. Peak: 1 h all routes. Duration: Inhaled: 1–5 h; PO 4 h. Metabolism: Metabolized in liver. Elimination: Excreted in urine.

Nursing Implications

Assessment & Drug Effects

Patient & Family Education


Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug