BRAND NAMES
- Belgium: Bricanyl
- Canada: Bricanyl PI
- France: Bricanyl
- Germany: Aerodur, Bricanyl
- International: Bricanyl
- Italy: Bricanyl
- Switzerland: Bricanyl
 MECHANISM OF ACTION
Terbutaline is a short-acting Beta2 adrenergic receptor agonist with a fast onset of action.
Beta2 receptors are the predominant adrenergic receptors in bronchial smooth muscle. The binding of Terbutaline to Beta2 adrenergic receptors in bronchial smooth muscle, activates the intracellular adenylate cyclase, an enzyme which catalyzes the conversion of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP). The increase of cAMP determines:
- Bronchodilation: Increased intracellular cyclic AMP (cAMP), increases the activation of cAMP-dependent protein kinase A, which inhibits the phosphorylation of myosin and lowers intracellular calcium levels within the muscle. Lower levels of calcium cause relaxation of the smooth muscle and therefore bronchodilatation.
- Inhibition of the release of mast cell mediators
Following inhalation, a significant improvement in pulmonary function is well established after 5 minutes. The maximal response is usually attained between 15 and 60 minutes following administration. Significant bronchodilator activity has been observed to persist for 4 to 7 hours
Symptomatic relief of bronchial asthma and bronchospasm which may occur in association with bronchitis and emphysema.
- Adults and children 6 years of age and older, 1 inhalation (500 mcg) taken as required. This will usually be adequate to relieve bronchospasm in the majority of patients, however, if required, a second dose may be taken, preferably after 5 minutes.
Maximum daily dosage: six inhalations (3 mg)
- Hypersensitivity to Terbutaline
- Patients with tachyarrhythmias
- Use with caution in patients with underlying cardiovascular disorders (Monitor heart rate), diabetes, hypertension, hyperthyroidism, and a history of seizures.
- Paradoxical bronchospasm may occur and should be treated immediately with alternative therapy
- Beta blockers: Beta blockers (medications used to slow down the heart beat), especially nonselective ones may block bronchodilatory effects of beta-agonists and produce severe bronchospasm. Patients with asthma should not normally be treated with beta blockers.
- Nonpotassium-sparing diuretics: As with other beta-agonists, Terbutaline may produce significant hypokalemia in some patients. Co-administration of nonpotassium-sparing diuretics (such as loop diuretics or thiazide diuretics) which cause hypokalemia as a side effect, may worsen hypokalemia . Consider monitoring potassium levels
 PREGNANCY AND LACTATION
- Pregnancy: The safe use of Terbutaline Inhaler has not been established in human pregnancy. The use of this drug in pregnancy, lactation, or women of child-bearing potential requires that the expected therapeutic benefit of the drug be weighed against its possible hazards to the mother or child.
- Nursing Mothers: Terbutaline is excreted in breast milk. Caution should be exercised when administered to nursing women.
 SIDE EFFECTS
Adverse effects include: Tremor, palpitations, restlessness, headache, muscle cramps, nervousness. Initial dose titrations will often reduce these reactions and most of these side effects are reversible within the first two weeks of treatment.
Sleep disturbances and behavioural disturbances, such as agitation, hyperactivity and restlessness, have been also observed
Serious but rare adverse effects: Paradoxical bronchospasm and cardiac arrhythmias (e.g., atrial fibrillation, supraventricular tachycardia and extrasystoles).