Yes (except inhaler)

Beta₂ Agonist

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

C

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

Breast-feeding/lactation: No data on crossing into breast milk or clinical effects on the infant

Hypersensitivity to metaproterenol or any components, pre-existing cardiac arrhythmias associated with tachycardia

Use with caution in patients with hypertension, CHF, hyperthyroidism, CAD, diabetes, or sensitivity to sympathomimetics; excessive prolonged use may result in decreased efficacy or increased toxicity and death; use caution in patients with pre-existing cardiac arrhythmias associated with tachycardia. Metaproterenol has more beta₁ activity than other sympathomimetics such as albuterol and, therefore, may no longer be the beta agonist of first choice. All patients should utilize a spacer device when using a metered dose inhaler. Oral use should be avoided due to the increased incidence of adverse effects.

>10%:

Central nervous system: Nervousness

Neuromuscular & skeletal: Tremor

1% to 10%:

Cardiovascular: Tachycardia, palpitations, hypertension

Central nervous system: Headache, dizziness

Gastrointestinal: Nausea, vomiting, bad taste

Neuromuscular & skeletal: Trembling, muscle cramps, weakness

Respiratory: Coughing

Miscellaneous: Diaphoresis (increased)

<1%: Paradoxical bronchospasm

Symptoms of overdose include angina, arrhythmias, tremor, dry mouth, insomnia; beta-adrenergic stimulation can increase and cause increased heart rate, decreased blood pressure, decreased CNS excitation

In cases of overdose, supportive therapy should be instituted, and prudent use of a cardioselective beta-adrenergic blocker (eg, atenolol or metoprolol) should be considered, keeping in mind the potential for induction of bronchoconstriction in an asthmatic individual. Dialysis has not been shown to be of value in the treatment of an overdose with this agent. Diazepam 0.07 mg/kg can be used for excitation seizures.

Decreased effect: Beta-blockers

Increased toxicity: Sympathomimetics, TCAs, MAO inhibitors

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

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

Oral:

Onset of bronchodilation: Within 15 minutes

Peak effect: Within 1 hour

Duration of action: ~1-5 hours

Inhalation:

Onset of effects: Within 60 seconds

Duration of action: Similar (~1-5 hours) regardless of route administered

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)

Assess lung sounds, pulse, and blood pressure before administration and during peak of medication; observe patient for wheezing after administration, if this occurs, call physician; monitor heart rate, respiratory rate, blood pressure, and arterial or capillary blood gases if applicable

potassium (S)

Nervousness is common; may cause dizziness, restlessness, or insomnia

Concurrent use with TCAs and MAOIs may result in additive toxicity

No information available to require special precautions

No effects or complications reported

Use exactly as directed (see Administration below). 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 (frequent small meals, frequent mouth care, chewing gum, or sucking hard candy may help); or increased perspiration. 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 be 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 1-3 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. Breath calmly and deeply until no more mist is formed in nebulizer (about 5 minutes). At this point treatment is finished.

Do not use solutions for nebulization if they are brown or contain a precipitate; before using, the inhaler must be shaken well

Aerosol, oral, as sulfate: 0.65 mg/dose (5 mL, 10 mL)

Solution for inhalation, as sulfate, preservative free: 0.4% [4 mg/mL] (2.5 mL); 0.6% [6 mg/mL] (2.5 mL); 5% [50 mg/mL] (10 mL, 30 mL)

Syrup, as sulfate: 10 mg/5 mL (480 mL)

Tablet, as sulfate: 10 mg, 20 mg

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.