Metaproterenol

Pronunciation

(met a proe TER e nol)

U.S. Brand Names

Alupent®

Synonyms

Metaproterenol Sulfate; Orciprenaline Sulfate

Generic Available

Yes; Excludes inhaler

Use

Bronchodilator in reversible airway obstruction due to asthma or COPD; because of its delayed onset of action (1 hour) and prolonged effect (4 or more hours), this may not be the drug of choice for assessing response to a bronchodilator

Pregnancy Risk Factor

Pregnancy Implications

No data on crossing the placenta. Reported association with polydactyly in 1 study; may be secondary to severe maternal disease or chance.

Lactation

Excretion in breast milk unknown

Contraindications

Hypersensitivity to metaproterenol or any component of the formulation; pre-existing cardiac arrhythmias associated with tachycardia

Warnings/Precautions

Optimize anti-inflammatory treatment before initiating maintenance treatment with metaproterenol. 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; additionally, a face mask should be used in children <4 years of age.

Metaproterenol has more beta1 activity than beta2-selective agents such as albuterol and, therefore, may no longer be the beta agonist of first choice. Oral use should be avoided due to the increased incidence of adverse effects.

Adverse Reactions

>10%:

Cardiovascular: Tachycardia (<17%)

Central nervous system: Nervousness (3% to 14%)

Endocrine & metabolic: Serum glucose increased, serum potassium decreased

Neuromuscular & skeletal: Tremor (1% to 33%)

1% to 10%:

Cardiovascular: Palpitations (<4%)

Central nervous system: Headache (<4%), dizziness (1% to 4%), insomnia (2%)

Gastrointestinal: Nausea, vomiting, bad taste, heartburn ( 4%), xerostomia

Neuromuscular & skeletal: Trembling, muscle cramps, weakness (1%)

Respiratory: Coughing, pharyngitis ( 4%)

Miscellaneous: Diaphoresis (increased) ( 4%)

<1%: Paradoxical bronchospasm, hypertension, hypokalemia, chest pain, angina, drowsiness, diarrhea, taste change

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

Beta-adrenergic blockers (eg, propranolol) antagonize metaproterenol's effects; avoid concurrent use.

Inhaled ipratropium may increase duration of bronchodilation.

MAO inhibitors may increase side effects; monitor heart rate and blood pressure.

TCAs may increase side effects; monitor heart rate and blood pressure.

Sympathomimetics may increase side effects; monitor heart rate and blood pressure.

Halothane may increase risk of malignant arrhythmias; avoid concurrent use.

Stability

Store in tight, light-resistant container; do not use if brown solution or contains a precipitate

Mechanism of Action

Relaxes bronchial smooth muscle by action on beta2-receptors with very little effect on heart rate

Pharmacodynamics/Kinetics

Onset of action: Bronchodilation: Oral: ~15 minutes; Inhalation: ~60 seconds

Peak effect: Oral: ~1 hour

Duration: ~1-5 hours

Dosage

Oral:

Children:

<2 years: 0.4 mg/kg/dose given 3-4 times/day; in infants, the dose can be given every 8-12 hours

2-6 years: 1-2.6 mg/kg/day divided every 6 hours

6-9 years: 10 mg/dose 3-4 times/day

Children >9 years and Adults: 20 mg 3-4 times/day

Elderly: Initial: 10 mg 3-4 times/day, increasing as necessary up to 20 mg 3-4 times/day

Inhalation: Children >12 years and Adults: 2-3 inhalations every 3-4 hours, up to 12 inhalations in 24 hours

Nebulizer:

Infants and Children: 0.01-0.02 mL/kg of 5% solution; minimum dose: 0.1 mL; maximum dose: 0.3 mL diluted in 2-3 mL normal saline every 4-6 hours (may be given more frequently according to need)

Adolescents and Adults: 5-20 breaths of full strength 5% metaproterenol or 0.2 to 0.3 mL 5% metaproterenol in 2.5-3 mL normal saline until nebulized every 4-6 hours (can be given more frequently according to need)

Administration

Inhalation: Do not use solutions for nebulization if they are brown or contain a precipitate. Shake inhaler well before using.

Oral: Administer around-the-clock to promote less variation in peak and trough serum levels

Monitoring Parameters

Assess lung sounds, heart rate, and blood pressure before administration and during peak of medication; observe patient for wheezing after administration, if this occurs, call physician; monitor respiratory rate, arterial or capillary blood gases if applicable; FEV1, peak flow, and/or other pulmonary function tests; CNS stimulation; serum glucose, serum potassium

Test Interactions

Increased potassium (S)

Patient Education

Use exactly as directed (see following administration information). 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); dry mouth, unpleasant aftertaste, stomach upset (small, frequent meals, frequent mouth care, chewing gum, or sucking hard candy may help); or increased perspiration. If you have diabetes, check blood sugar; blood glucose level 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. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to become pregnant. Consult prescriber if breast-feeding.

Self-administered inhalation: Store canister upside down; do not freeze. Shake canister before using. Sit when using medication. Close eyes when administering metaproterenol 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.

Self-administered nebulizer: Wash hands before and after treatment. Wash and dry nebulizer after each treatment. Twist open the top of one unit dose vial and squeeze contents into nebulizer reservoir. Connect nebulizer reservoir to the mouthpiece or face mask. Connect nebulizer to compressor. Sit in comfortable, upright position. Place mouthpiece in your mouth or put on face mask and turn on compressor. If face mask is used, avoid leakage around the mask to avoid mist getting into eyes which may cause vision problems. Breathe calmly and deeply until no more mist is formed in nebulizer (about 5 minutes). At this point treatment is finished.

Additional Information

Use with caution perioperatively due to beta1 effect of agent. Hypertension and tachycardia are increased with exogenous sympathomimetics. During endotracheal intubation, beta2-specific agent is more appropriate for perioperative use.

Anesthesia and Critical Care Concerns/Other Considerations

Hypertension and tachycardia are increased with exogenous sympathomimetics. During endotracheal intubation, beta2-specific agent is more appropriate for perioperative use. Use with caution perioperatively due to beta1 effect of agent.

Dental Health: Effects on Dental Treatment

Key adverse event(s) related to dental treatment: Bad taste and 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 is common; may cause dizziness, restlessness, or insomnia

Mental Health: Effects on Psychiatric Treatment

Concurrent use with TCAs and MAO inhibitors may result in additive toxicity

Dosage Forms

Aerosol for oral inhalation, as sulfate (Alupent®): 0.65 mg/inhalation (14 g) [200 doses]

Solution for oral inhalation, as sulfate [preservative free]: 0.4% [4 mg/mL] (2.5 mL); 0.6% [6 mg/mL] (2.5 mL)

Syrup, as sulfate: 10 mg/5 mL (480 mL) [may contain sodium benzoate]

Tablet, as sulfate: 10 mg, 20 mg

References

Gilman MJ, Meyer L, Carter J, et al, "Comparison of Aerosolized Glycopyrrolate and Metaproterenol in Acute Asthma," Chest , 1990, 98(5):1095-8.

Jerrard DA, Olshaker J, Welebob E, et al, "Efficacy and Safety of a Rapid-Sequence Metaproterenol Protocol in the Treatment of Acute Adult Asthma," Am J Emerg Med , 1995, 13(4):392-5.

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.

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