Terbutaline sulfate

Terbutaline sulfate
INN
Drug class
Routes of administration	Oral, inhalation, subcutaneous
Pregnancy category
Bioavailability	14.8% (oral)
Metabolism	Hepatic
Elimination half-life	3-4 hours
Excretion	Renal
Legal status
CAS Number	23031-32-5
PubChem	5403
DrugBank	DB00871
ChemSpider	5208
KEGG	D08545

Terbutaline sulfate is a beta-2 adrenergic receptor agonist used primarily as a bronchodilator in the management of asthma and chronic obstructive pulmonary disease (COPD). It is also used off-label as a tocolytic agent to delay premature labor.

Pharmacology

Mechanism of Action

Terbutaline sulfate works by stimulating beta-2 adrenergic receptors in the smooth muscle of the bronchi and uterus. This stimulation leads to the activation of adenylate cyclase, which increases the levels of cyclic adenosine monophosphate (cAMP). Elevated cAMP levels result in the relaxation of smooth muscle, leading to bronchodilation and uterine relaxation.

Pharmacokinetics

Terbutaline is administered via oral, inhalation, or subcutaneous routes. It has a bioavailability of approximately 14.8% when taken orally due to extensive first-pass metabolism in the liver. The drug is metabolized hepatically and has an elimination half-life of 3-4 hours. It is primarily excreted in the urine.

Clinical Uses

Asthma and COPD

Terbutaline is used as a bronchodilator to relieve symptoms of asthma and chronic obstructive pulmonary disease (COPD). It is effective in reducing bronchospasm and improving airflow in patients with obstructive airway diseases.

Tocolysis

Although not approved for this use in many countries, terbutaline is sometimes used off-label as a tocolytic to delay premature labor. It relaxes the uterine smooth muscle, thereby inhibiting contractions.

Adverse Effects

Common side effects of terbutaline include tremor, nervousness, dizziness, headache, and palpitations. More serious adverse effects can include tachycardia, hypokalemia, and hyperglycemia.

Contraindications

Terbutaline is contraindicated in patients with a history of hypersensitivity to the drug or any of its components. It should be used with caution in patients with cardiovascular disease, diabetes mellitus, and hyperthyroidism.

Interactions

Terbutaline may interact with other medications, including beta-blockers, which can reduce its effectiveness. It may also interact with other sympathomimetic agents, leading to increased cardiovascular effects.

Regulatory Status

Terbutaline is classified as a prescription-only medication in many countries, including the United States, the United Kingdom, and Australia. It is available under various brand names, including Bricanyl.

See Also

• Beta-2 adrenergic receptor agonist
• Bronchodilator
• Tocolytic

External Links

• Drugs.com: Terbutaline
• MedlinePlus: Terbutaline