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Terbutaline Sulfate

Pronunciation

Pronunciation: ter-BUE-ta-leen SUL-fate
Class: Sympathomimetic

Trade Names

Terbutaline Sulfate
- Tablets, oral 2.5 mg
- Tablets, oral 5 mg
- Injection, solution 1 mg/mL

Bricanyl Turbuhaler (Canada)

Pharmacology

Produces bronchodilation by relaxing bronchial smooth muscle through beta 2 -receptor stimulation.

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Pharmacokinetics

Absorption

C max is approximately 8.5 ng/mL, T max is approximately 1 to 3 h, and AUC is approximately 54 ng•h/mL. Terbutaline bioavailability is 103%.

Metabolism

The sulfate conjugate is the major metabolite.

Elimination

Half-life is approximately 3.4 h (oral) and 2.9 h (subcutaneous). Approximately 90% is excreted in urine at 96 h after subcutaneous administration, with approximately 60% being unchanged drug. Urinary excretion is the primary route of elimination.

Onset

Onset of action is 30 min.

Peak

Time to peak effect is 120 to 180 min.

Duration

Duration of action is 4 h or longer.

Indications and Usage

For prevention and reversal of bronchospasm associated with asthma, bronchitis, and emphysema.

Contraindications

Acute and maintenance tocolysis (oral) or prolonged tocolysis (injection); hypersensitivity to sympathomimetic amines or any component of the product.

Dosage and Administration

Adults and Children older than 15 y

PO 5 mg 3 times daily, at 6 h intervals during waking hours (max, 15 mg/day). Decrease dosage to 2.5 mg 3 times daily if intolerable adverse reactions occur.

Children 12 to 15 y of age

PO 2.5 mg 3 times daily, at 6 h intervals during waking hours (max, 7.5 mg/day).

Adults and Children 12 y and older

Subcutaneous 0.25 mg as a single dose. May repeat in 15 to 30 min. Do not exceed 0.5 mg as a total dose in 4 h.

General Advice

  • Injection is for subcutaneous use only.
  • Subcutaneous injections should be made in the lateral deltoid area.
  • Limit subcutaneous doses to up to 0.5 mg in 4 h.
  • Vials/ampules are single-use only; discard unused portions.

Storage/Stability

Store between 59° and 86°F (tablets) and 68° and 77°F (vials/ampules). Protect from light.

Drug Interactions

Beta-blockers (eg, propranolol)

Block bronchodilator effect of terbutaline. Patients with asthma should not normally be treated with beta-blockers. However, under certain circumstances (eg, as prophylaxis after MI), there may be no acceptable alternatives to the use of beta-blocking agents in patients with asthma. In this setting, cardioselective beta-blockers could be considered, although they should be administered with caution.

Catechol-O-methyl transferase inhibitors (eg, entacapone, tolcapone)

The pathway responsible for terbutaline metabolism may be inhibited. Excessive sympathetic stimulation may result. Close clinical monitoring for signs of excessive sympathetic activity is warranted.

Loop diuretics (eg, furosemide), thiazide diuretics (eg, hydrochlorothiazide)

The ECG changes or hypokalemia that may result from the administration of non–potassium-sparing diuretics can be acutely worsened by beta-agonists, such as terbutaline, especially when the recommended dose of terbutaline is exceeded. Although the clinical importance of these effects is not known, caution is advised with coadministration.

MAOIs (eg, linezolid, phenelzine)

Hypertension may occur. Administer with extreme caution to patients being treated with an MAOI, or within 2 weeks of discontinuation of an MAOI.

QT-prolonging drugs (eg, antiarrhythmic agents [eg, amiodarone], mesoridazine, pimozide, ziprasidone)

An additive effect with terbutaline cannot be excluded. Use with caution and close clinical monitoring.

Sympathomimetic agents (eg, ephedrine)

Concomitant use with other sympathomimetic agents is not recommended, because the combined effect on the CV system may be deleterious to the patient. However, this does not preclude the use of an aerosol bronchodilator of the adrenergic-stimulant type for the relief of an acute bronchospasm in patients receiving long-term oral therapy with terbutaline.

Tricyclic antidepressants (eg, amitriptyline)

CV effects of terbutaline may be enhanced. Administer with extreme caution to patients being treated with a tricyclic antidepressant, or within 2 weeks of discontinuation of a tricyclic antidepressant.

Adverse Reactions

Cardiovascular

Palpitations (23%); tachycardia (4%); ventricular extrasystoles (2%); vasodilations (1%).

CNS

Tremor (38%); nervousness (35%); drowsiness (12%); dizziness (10%); headache (9%); somnolence (6%); asthenia, insomnia (2%); anxiety, weakness (1%).

Dermatologic

Sweating (2%).

GI

Nausea/vomiting (4%); dry mouth (2%).

Hepatic

Elevated liver enzymes.

Metabolic

Hypokalemia.

Respiratory

Dyspnea (2%).

Miscellaneous

Pain at injection site (3%); chest discomfort, flushed feeling (2%).

Precautions

Warnings

Terbutaline has not been approved and should not be used for acute or maintenance tocolysis. Do not use terbutaline for maintenance tocolysis in the outpatient setting. Serious adverse reactions, including death, have been reported after administration to pregnant women. In pregnant women, these adverse reactions include increased heart rate, transient hyperglycemia, hypokalemia, cardiac arrhythmias, pulmonary edema, and MI. Increased fetal heart rate and neonatal hypoglycemia may occur.


Monitor

Monitor pulmonary function tests and for reduced asthma symptoms. Monitor for significant CV effects (eg, changes in BP, heart rate, ECG).


Pregnancy

Category C .

Lactation

Excreted in breast milk (per Briggs' Drugs in Pregnancy and Lactation ). The American Academy of Pediatrics classifies terbutaline as compatible with breast-feeding.

Children

Safety and efficacy in children younger than 12 y not established.

Elderly

Lower doses may be required.

Labor and Delivery

May inhibit uterine contractions and delay preterm labor.

Hypersensitivity

Hypersensitivity and exacerbations of bronchospasm have been reported.

CV effects

Beta-adrenergic agonists can produce a clinically significant CV effect in some patients as measured by pulse rate, BP, or symptoms. Reports of ECG changes, such as flattening of the T wave, prolongation of the QTc interval, and ST-segment depression, have occurred.

Diabetes

May aggravate preexisting diabetes mellitus and ketoacidosis.

Hypokalemia

Decreases in potassium levels have occurred.

Seizures

May occur.

Special risk

Use with caution in patients with CV disorders, including ischemic heart disease, hypertension, and cardiac arrhythmias; patients with hyperthyroidism or diabetes mellitus; patients who are unusually responsive to sympathomimetic amines; and patients with convulsive disorders.

Overdosage

Symptoms

Angina, arrhythmia, dizziness, dry mouth, fatigue, headache, hypertension, hypokalemia, hypotension, insomnia, malaise, nausea, nervousness, palpitation, seizure, tachycardia, tremor.

Patient Information

  • Advise patient to take tablets with food to avoid GI upset.
  • Inform patient that the drug can stop working over time. If this is noted, advise the patient to notify their health care provider at once.
  • Instruct patient to report these symptoms to health care provider: chest pain, dizziness or headache, palpitations, persisting symptoms of asthma.
  • Advise patients not to use terbutaline more often than prescribed. If symptoms persist, promptly consult a health care provider.

Copyright © 2009 Wolters Kluwer Health.

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