Molecule

Drug Groups

approved

Description

A selective beta-2 adrenergic agonist used as a bronchodilator and tocolytic. [PubChem]

Indication

For the prevention and reversal of bronchospasm in patients 12 years of age and older with reversible, obstructive airway disease, as well as symptomatic management of reversible bronchospasm associated with bronchitis and emphysema. Also used acute IV and sub-Q therapy in selected women to inhibit uterine contractions in preterm labor (tocolysis) and prolong gestation when beneficial.

Pharmacology

Terbutaline is a relatively selective beta2-adrenergic bronchodilator that has little or no effect on alpha-adrenergic receptors. The drug has exerts a preferential effect on beta2-adrenergic receptors but stimulates beta-adrenergic receptors less selectively than relatively selective beta2-agonists. Terbutaline appears to have a greater stimulating effect on beta-receptors of the bronchial, vascular, and uterine smooth muscles (beta2 receptors) than on the beta-receptors of the heart (beta1 receptors). This drug relaxes smooth muscle and inhibits uterine contractions, but may also cause some cardiostimulatory effects and CNS stimulation.

Toxicity

Terbutaline Sulfate: Oral LD₅₀(rat) = 8.7 g/kg; Oral LD₅₀(mouse) = 205 mg/kg; Oral LD₅₀(dog) = 1.5 g/kg; IP LD₅₀(rat)= 220 mg/kg ; IP LD₅₀(mouse) = 130 mg/kg; Oral LD₅₀(rabbit) = >8 g/kg; IV LD₅₀(mouse) = 36 mg/kg; IV LD₅₀(dog) = 116 mg/kg; IV LD₅₀(rabbit) = 110 mg/kg

Affected Organisms

Absorption

Approximately 30-50% if administered orally and well absorbed subcutaneously.

Half Life

5.5-5.9 hours

Elimination

About 90% of the drug was excreted in the urine at 96 hours after subcutaneous administration, with about 60% of this being unchanged drug. It appears that the sulfate conjugate is a major metabolite of terbutaline and urinary excretion is the primary route of elimination

Clearance

* 311 +/- 112 mL/min

References

External Links