Adult: As metered-dose powd inhaler: 250-500 mcg as required. Max: 2,000 mcg daily.
Inhalation/Respiratory Severe bronchospasm
Adult: As 1% nebuliser soln: 2.5-10 mg 2-4 times daily. Child: <25 kg: 2-5 mg 2-4 times daily; ≥25 kg: 5 mg 2-4 times daily.
Intravenous Uncomplicated premature labour
Adult: To arrest labour between 22-37 wk of gestation: Initially, 5 mcg/min, w/ increments of 2.5 mcg/min at 20 min intervals until contractions stop. Max: 20 mcg/min. Continue for 1 hr after contractions have ceased, then decrease by 2.5 mcg/min every 20 min to lowest dose that maintains suppression. Max duration: 48 hr.
Oral Acute bronchospasm
Adult: Initially, 2.5 mg or 3 mg tid, up to 5 mg tid as necessary. As modified-release tab: 5 mg or 7.5 mg bid. Child: <12 yr Initially, 0.05 mg/kg/dose tid, increase gradually as required. Max: 5 mg/day; 12-15 yr 2.5 mg tid; >15 yr Same as adult dose.
Parenteral Severe bronchospasm
Adult: 250-500 mcg up to 4 times daily by SC, IM or IV inj, or by IV infusion as a soln containing 3-5 mcg/mL at a rate of 0.5-1 mL/min. Child: 2-15 yr 0.01 mg/kg. Max: 0.3 mg/dose.
Administration
May be taken with or without food.
Reconstitution
Add 10 mL of terbutaline soln for inj to 40 mL of dextrose 5% if using a syringe pump or to 490 mL of dextrose 5% if syringe pump is not available.
Contraindications
Parenteral: Prolonged (beyond 48-72 hr) or maintenance tocolysis, particularly in outpatient or home setting. PO: Acute or maintenance tocolysis.
Monitor cardiorespiratory function, serum K and glucose levels; signs/symptoms of pulmonary oedema (when used in premature labour).
Overdosage
Symptoms: Headache, anxiety, tremor, nausea, tonic cramps, palpitations, tachycardia, arrhythmia; hypotension, hypokalaemia, hyperglycaemia and lactic acidosis may occur. Management: Reduce dose in mild to moderate cases. In severe cases, perform necessary tests to determine acid-base balance, blood sugar and electrolyte levels. Monitor BP, heart rate and rhythm and correct metabolic changes. A cardioselective β-blocker (e.g. metoprolol) may be given for the treatment of arrhythmias but w/ caution.
Drug Interactions
Increased risk of haemorrhage and serious ventricular rhythm disorder w/ halogenated anaesth. May reduce the effect of anti-diabetic drugs. Increased risk of hypokalaemia w/ K-depleting agents (e.g. diuretics). Concomitant β-agonist and corticosteroid may result to pulmonary oedema. May partially or totally inhibit the effect of non-selective β-blockers.
Action
Description: Terbutaline stimulates intracellular adenyl cyclase, the enzyme that catalyses the conversion of ATP to cyclic-3', 5'-adenosine monophosphate (cAMP) resulting in relaxation of bronchial smooth muscle and inhibition of release of mediators of immediate hypersensitivity from mast cells. Onset: W/in 5 min (inhalation); 30-45 min (oral); 6-15 min (SC). Duration: 6 hr (inhalation); 8 hr (oral). Pharmacokinetics: Absorption: Variably absorbed from the GI tract; absorbed from the airways (<10%). Bioavailability: Approx 14-15% (oral). Time to peak plasma concentration: 1-4 hr. Distribution: Crosses the placenta and enters breast milk (trace amounts). Plasma protein binding: 25%. Metabolism: Undergoes extensive first-pass metabolism via sulfate and some glucoronide conjugation in the liver and the gut wall. Excretion: Via urine and faeces as inactive sulfate conjugate and unchanged drug. Terminal half-life: 16-20 hr.
Chemical Structure
Terbutaline Source: National Center for Biotechnology Information. PubChem Database. Terbutaline, CID=5403, https://pubchem.ncbi.nlm.nih.gov/compound/Terbutaline (accessed on Jan. 23, 2020)
R03CC03 - terbutaline ; Belongs to the class of adrenergics for systemic use, selective beta-2-adrenoreceptor agonists. Used in the treatment of obstructive airway diseases. R03AC03 - terbutaline ; Belongs to the class of adrenergic inhalants, selective beta-2-adrenoreceptor agonists. Used in the treatment of obstructive airway diseases.
References
Anon. Terbutaline. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 15/07/2015.Buckingham R (ed). Terbutaline Sulfate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 15/07/2015.McEvoy GK, Snow EK, Miller J et al (eds). Terbutaline Sulfate. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 15/07/2015.Terbutaline Sulfate Tablet (Marlex Pharmaceuticals Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 15/07/2015.
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