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Terbutaline Sulfate

Pronunciation: (ter-BYOO-tuh-leen SULL-fate)
Class: Sympathomimetic

Trade Names:
Brethaire
- Aerosol 0.2 mg/actuation

Trade Names:
Brethine
- Tablets 2.5 mg
- Tablets 5 mg
- Injection 1 mg/mL

Trade Names:
Bricanyl
- Tablets 2.5 mg
- Tablets 5 mg
- Injection 1 mg/mL

Bricanyl Turbuhaler (Canada)

Pharmacology

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

Pharmacokinetics

Absorption

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

Metabolism

The sulfate conjugate is the major metabolite.

Elimination

Terbutaline t _½ is about 3.4 h. Approximately 90% is excreted in urine at 96 h after subcutaneous administration, with about 60% being unchanged drug. Urinary excretion is the primary route of elimination.

Onset

Onset of action is 30 min.

Peak

Time to peak effect of terbutaline is 120 to 180 min.

Duration

Duration of action is 4 h or longer.

Indications and Usage

Treatment of reversible bronchospasm associated with asthma, bronchitis, and emphysema.

Contraindications

Cardiac arrhythmias associated with tachycardia.

Dosage and Administration

Adults and Children older than 15 yr of age

PO 2.5 to 5 mg at 6 h intervals, 3 times daily during waking hours. Do not exceed 15 mg in 24 h.

Children 12 to 15 yr of age

PO 2.5 mg 3 times daily. Do not exceed 7.5 mg in 24 h. Subcutaneous 0.25 mg given in lateral deltoid area. May repeat in 15 to 30 min. Do not exceed 0.5 mg in 4 h.

General Advice

For IV administration, obtain baseline potassium level prior to administration and place patient on cardiac monitor to assess for tachycardia or arrhythmias. Toxic symptoms have been documented in patients with CV disorders.
Do not allow patient to use inhaler form of medication more than 6 times/day.
Limit subcutaneous doses to up to 0.5 mg in 4 h.

Storage/Stability

Store at room temperature. Protect from light.

Drug Interactions

Beta-blockers

Block bronchodilator effect of terbutaline.

MAOIs

Hypertension may occur.

Tricyclic antidepressants

CV effects of terbutaline may be enhanced.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Palpitations; tachycardia; chest discomfort or pain; arrhythmias; BP changes/hypertension.

CNS

Stimulation; tremor; dizziness; nervousness; drowsiness; headache; weakness.

GI

Nausea; vomiting; GI distress.

Hepatic

Elevated liver enzymes.

Metabolic

Hypokalemia (with high doses).

Respiratory

Dyspnea.

Miscellaneous

Flushing; sweating; muscle cramps; hypersensitivity vasculitis; ECG changes (eg, sinus pause, atrial premature beats, AV block, ventricular premature beats, ST-T-wave depression, T-wave inversion, sinus bradycardia, atrial escape beat with aberrant conduction); increased heart rate; muscle cramps; central stimulations; pain at injection site; elevations in liver enzymes; seizures; hypersensitivity vasculitis.

Precautions

Pregnancy

Category B .

Lactation

Excreted in breast milk.

Children

Safety and efficacy in children younger than 12 yr of age not established.

Elderly

Lower doses may be required.

Labor and Delivery

May inhibit uterine contractions and delay preterm labor.

Hypersensitivity

Hypersensitivity (allergic) reactions can occur after administration.

Carcinogenesis

A significant increase in the incidence of leiomyomas of the mesovarium and ovarian cysts has been demonstrated.

CV effects

Toxic symptoms in patients with CV disorders may occur.

CNS effects

CNS stimulation may occur; use cautiously in patients with history of seizures or hyperthyroidism.

Diabetes

Dosage adjustment of insulin or oral hypoglycemic agent may be required.

Excessive use

Paradoxical bronchospasm and cardiac arrest have been associated with excessive inhalant use.

Hypokalemia

Decreases in potassium levels have occurred.

Tolerance

If previously effective dose fails to provide relief, therapy may need to be reassessed.

Overdosage

Symptoms

Tremor, palpitations, increased heart rate, decreased BP, seizures, hypokalemia, muscle cramps, headache, hyperglycemia.

Patient Information

Instruct patient on proper technique for use of inhalers and evaluate return demonstration.
Demonstrate use of spacer or peak flow meter if prescribed.
Caution patient not to use inhaler form of medication more than 6 times/day.
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 or if the inhalation makes breathing worse, notify the health care provider at once.
Instruct patient to report these symptoms to health care provider: chest pain, dizziness or headache, persisting symptoms of asthma.