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Terbutaline is a selective beta2 agonist, used in the symptomatic treatment of bronchial asthma and some other chronic lung diseases. In addition, the drug is also indicated in the management of threatened preterm birth in some cases. The following article provides you with information about the uses and possible side effects of using Terbutaline.
1. What are the effects of Terbutaline?
Terbutaline drug belongs to the group of bronchodilators, selective beta2 agonists and uterine contractions.
Terbutaline is a synthetic sympathomimetic, beta2-adrenergic agonist. Terbutaline has a stimulant effect on beta receptors of the sympathetic nervous system and has no effect on alpha receptors. Terbutaline has the main effect of relaxing bronchial smooth muscle, uterus and peripheral vessels. The drug reduces airway resistance, thereby increasing the forced expiratory volume in 1 second (FEV1). Terbutaline does not directly alter arterial oxygen pressure. The drug stimulates the production of adenosine-3',5'-cyclic monophosphate (AMPc) by activating the enzyme adenyl cyclase.
Terbutaline has a strong stimulant effect on beta2 receptors of the bronchi, uterine smooth muscle, blood vessels and very little effect on beta1 receptors of the heart. However, when used in high doses, Terbutaline can cause irritation of the heart and central nervous system. Terbutaline occasionally increases heart rate, but the mechanism is unknown, possibly due to terbutaline stimulation of beta1 receptors, or a reflex response to changes in blood pressure due to peripheral vasodilation.
Dosage forms and content of the drug are as follows:
Tablets: 2.5mg and 5mg. Syrup: 1.5mg/ml. Syringe: 0.5mg/ml; mg/ml. Single dose spray pump: 5mg. metered dose inhaler: 0.25mg/dose. Single dose nebulizer: 5mg/2ml. Multi-dose nebulizer: 10mg/ml (50ml). Vial of divided dose inhalation powder: 0.5mg.
2. Indications and contraindications for the drug Terbutaline
Terbutaline is indicated in the treatment of the following cases:
Symptomatic treatment of bronchial asthma and exacerbation of chronic obstructive pulmonary disease, chronic bronchitis, emphysema when bronchospasm persists. recoverable. Management of threatened preterm birth in selected cases (between 24 and 33 weeks gestation). Terbutaline is contraindicated for use in the following cases:
Allergy or hypersensitivity to Terbutaline or any other ingredient in the drug and other sympathomimetic amines. Parenteral form: related to cardiovascular effects of terbutaline: severe heart failure; severe or uncontrolled blood pressure (including toxemia of pregnancy); thyrotoxicosis; eclampsia, preeclampsia. Spray form: there are signs of drug intolerance, when the spray pump causes bronchospasm or a lot of cough. In the management of threatened preterm birth: uterine bleeding, infection of the amniotic fluid, prolongation of pregnancy if there is danger to the mother or child (especially when the membranes have broken, the cervix dilates more than 4 cm). Terbutaline injection should not be used for a prolonged period (more than 48-72 hours) to inhibit uterine contractions in preterm labor. Oral terbutaline is not used in the prevention and management of preterm labor, especially when used outside the clinic or at home.
3. How to take the drug Terbutaline
Terbutaline is a rapid and short acting beta2 agonist, inhaled only when clinically indicated (to relieve asthma), should not be used regularly.
If it is necessary to inhale Terbutaline regularly (2 or more times per day), additional anti-inflammatory drugs (inhaled corticosteroids) must be used.
3.1. Dosage Treatment of bronchospasm
Inhalation form: Inhalation powder, used for adults and children from 5 years old: Dosage 500microgram (1 inhalation), if symptoms persist, can inhale up to 4 times /day. Nebulizer: Dosage for adults: 5 - 10mg/time x 2 - 4 times/day, can be used more if acute asthma is severe. Dosage for children: < 3 years old: 2mg/time x 2-4 times/day. Children from 3-5 years old, average weight 15kg: dose 3mg/time x 2-4 times/day. Children from 6-7 years old, average weight 20kg: dose 4mg/time x 2-4 times/day. Children over 8 years old, average weight ≥ 25 kg: 5mg/time x 2-4 times/day. Measuring dose inhaler: dose for adults and children: 250 - 500 micrograms (1 - 2 sprays). If symptoms persist, can spray up to 3-4 times / day. Oral (when inhalation is not effective): Dosage for adults: 2.5 - 3mg/time x 3 times/day; May increase to 5mg/time x 3 times/day if needed. The total dose should not exceed 15mg/day. Dosage for children: oral dose for children under 12 years old is not recommended in the US, but in the UK there are dosage guidelines as follows: 1 month - 7 years old: 75mcg/kg dose, 3 times/day; Children from 7 to 15 years old: dose 2.5mg/time x 2 - 3 times/day. The total dose of Terbutaline should not exceed 7.5 mg/day. Injection form: treatment of severe bronchospasm, can be administered subcutaneously, intramuscularly, or intravenously slowly: dose in adults 250-500mcg/time, maximum 4 times/day; children 2-15 years old (subcutaneously or intravenously) 10mcg/kg (maximum 300micrograms), up to 4 times/day. Intravenous infusion: Use Terbutaline solution containing 3 - 5 mcg/ml, intravenous infusion at a rate of 0.5 - 1 ml/min for adults (1.5 - 5 mcg/min, for 8 - 10 hours). Children 1 month - 18 years: first loading dose 2 - 4 mcg/kg, then 1 - 10 mcg/kg/hour depending on patient response and heart rate (maximum 300 mcg/hour). Management of threatened preterm labor
Use Terbutaline for the purpose of delaying labor for at least 48 hours for corticosteroid therapy or to transfer the woman to another medical unit:
Intravenous: Terbutaline is given by intravenous drip IV in 5% glucose solution, using an auto-injector when the concentration is 100 mcg/ml. If an auto-injector is not available, a concentration of 10 mcg/ml must be used. The recommended initial rate is 5 mcg/min, increased by 2.5 mcg/min every 20 minutes, until contractions have ceased. Usually, a rate of 10 mcg/min is sufficient; should not be infused at a rate exceeding 20 mcg/min. If this maximum rate is reached without delaying labor, the terbutaline infusion should be discontinued. During the infusion of Terbutaline, monitor the mother's pulse to avoid a heart rate exceeding 135-140 beats/min. Monitor the status of rehydration for the mother, because a lot of fluid can cause acute pulmonary edema. Once uterine contractions have ceased and terbutaline has been infused for 1 hour, reduce the dose by approximately 2.5 mcg/min every 20 minutes until the lowest maintenance dose without uterine contractions is reached. After 12 hours, maintenance can be started orally, 5mg/time x 3 times/day. However, this approach is not recommended, because the risk to the mother increases after 48 hours and there is no additional benefit with further treatment. Possibly after intravenous infusion, give 250 mcg subcutaneously 4 times a day for a few days before initiating oral administration. Subcutaneous injection: In case of decreasing uterine contractions, 0.25mg is injected every 20 minutes to 3 hours. If heart rate exceeds 120 beats/min, stop terbutaline temporarily. Terbutaline should not be given by prolonged injection to inhibit uterine contractions for more than 48-72 hours. 3.2. Overdosage and management Overdose of Terbutaline can cause symptoms similar to unwanted effects, but to a more severe degree.
Treatment of acute Terbutaline overdose includes symptomatic treatment, cardiac and respiratory support. Emesis should be performed, followed by gastric lavage, if the patient has just received oral medication and is conscious. If the patient cannot vomit, perform gastric lavage after intubation. Applying activated charcoal can help.
4. Terbutaline side effects
When administered intravenously, Terbutaline can cause many complications. Monitor regularly and stop the drug as soon as there is a serious complication. With oral or subcutaneous terbutaline, you may experience some of the following side effects:
Cardiovascular: changes in blood pressure, increased heart rate, palpitations, pulmonary edema, vasculitis, myocardial infarction. Central nervous system: nervous excitement, dizziness, muscle tremors, headache, restlessness, trouble sleeping, or lethargy, somnolence, convulsions. Gastrointestinal: dry mouth, unpleasant taste in the mouth, vomiting, nausea. Skin: pain at injection site, urticaria, skin rash. Musculoskeletal: cramps, muscle weakness. Metabolism: glucose intolerance, hyperglycemia, hypokalemia. Adverse effects of terbutaline by mouth, inhalation, or subcutaneous injection are usually transient and do not require treatment. However, the increased heart rate usually lasts a relatively long time.
Quantify blood glucose, blood potassium, do electrocardiogram, before and during treatment. In case of serious side effects, patients need to stop using Terbutaline and take them to the nearest medical facility for timely treatment.
5. Note when using Terbutaline drug
Respiratory disease Oral inhalation therapy with rapid-acting beta2-agonists, including terbutaline, is used to treat reversible bronchospasm in asthma, chronic obstructive pulmonary disease and should not be used. for maintenance therapy (ie 4 times/day) in asthma. If the asthma attack does not completely resolve after subcutaneous injection of terbutaline, or the symptoms reappear several hours after taking the drug, there is a risk of progression to severe asthma, the patient should be referred to a medical facility. Parenteral terbutaline should be used with caution in patients with diabetes, hyperthyroidism, hypertension, history of seizures, or cardiovascular disease (myocardial ischemia, coronary insufficiency, or associated arrhythmias). heart). When cardiovascular side effects appear, Terbutaline must be discontinued. High doses of intravenous terbutaline can worsen diabetes and cause ketoacidosis. High-dose beta2-agonists, mainly parenteral, can cause hypokalemia. Monitor serum potassium, especially when used concomitantly with drugs that lower blood potassium, or in patients at risk of torsades de pointes (QT prolongation). Beta blockers may partially or completely block the effects of beta2 agonists. Obstetrics and Gynecology Systemically administered beta2-agonists may reveal an unknown pre-existing cardiovascular disease. Many serious adverse events, including death, have been reported after administration of Terbutaline to pregnant women: tachycardia, transient hyperglycemia, hypokalemia, cardiac arrhythmias, pulmonary edema, and ischemic events. cardiac muscle. In addition, the fetus may appear tachycardia, hypoglycemia. The risk of serious adverse events outweighs any benefit when terbutaline is used to inhibit prolonged uterine contractions (more than 48-72 hours) by injection or orally. The manufacturer recommends that oral terbutaline not be used to inhibit or maintain uterine contractions and is contraindicated in this situation. Terbutaline should be used with caution in pregnant women when it is necessary to treat bronchospasm during labor, only when the benefit outweighs the risk to the mother and fetus. Lactation: Terbutaline is excreted in breast milk, but in small amounts it is not enough to cause harm to a nursing infant. However, caution should be exercised when terbutaline is used in lactating women, weighing the potential benefit to the mother against the risk to the infant. In case it is necessary to use Terbutaline, in order not to affect the baby, breast-feeding should be stopped. Sports: Be aware that Terbutaline may cause a positive anti-doping test.
6. Drug interactions
Sympathomimetic drugs: should not be used concurrently with Terbutaline because of the potential for increased cardiovascular events. However, nebulized sympathomimetic agents, to dilate the bronchi, can be used in patients receiving prolonged oral terbutaline. Theophylline derivatives: Animal studies have shown that concomitant administration of Terbutaline and theophylline derivatives such as aminophylin, may increase cardiotoxicity, cardiac arrhythmias. MAO inhibitors or tricyclic antidepressants: combined with Terbutaline increases the harm on the cardiovascular system. Loop diuretics or thiazides: ECG changes or hypokalemia when used in combination with terbutaline. Beta-adrenergic blocker (Propranolol): Terbutaline should not be combined with this medicine.
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