Domvent St

Uses

Used to open up the airways in people with asthma, bronchitis and other breathing problems.Used to relieve trouble breathing upon exertion.For the prevention and reversal of bronchospasm in patients 12 years of age and older with reversible, obstructive airway disease.Symptomatic management of reversible bronchospasm associated with bronchitis and emphysema.

This is used for the symptomatic treatment of reversible bronchoconstriction associated with bronchial asthma, chronic obstructive pulmonary emphysema, chronic bronchitis and related bronchospastic disorders.

Domvent St is also used to associated treatment for these conditions: Asthma, Bronchospasm, Chronic Cough (CC), Chronic Obstructive Pulmonary Disease (COPD), Cough, Premature Labour, Productive cough, Airway secretion clearance therapyAsthma, Bronchitis, Bronchoconstriction, Bronchospasm, Chronic Obstructive Pulmonary Disease (COPD), Chronic bronchial inflammation, Airway secretion clearance therapy, Bronchodilation

How Domvent St works

Terbutaline is a selective beta-2 adrenergic receptor agonist. Agonism of these receptors in bronchioles activates adenylyl cyclase, increasing intracellular cyclic adenosine monophosphate (cAMP). Increased cAMP decreases intracellular calcium, activating protein kinase A, inactivating myosin light-chain kinase, activating myosin light-chain phosphatase, and finally relaxing smooth muscle in the bronchiole.

Theophylline relaxes the smooth muscle of the bronchial airways and pulmonary blood vessels and reduces airway responsiveness to histamine, methacholine, adenosine, and allergen. Theophylline competitively inhibits type III and type IV phosphodiesterase (PDE), the enzyme responsible for breaking down cyclic AMP in smooth muscle cells, possibly resulting in bronchodilation. Theophylline also binds to the adenosine A2B receptor and blocks adenosine mediated bronchoconstriction. In inflammatory states, theophylline activates histone deacetylase to prevent transcription of inflammatory genes that require the acetylation of histones for transcription to begin.

Dosage

Domvent St dosage

The recommended adult dose for treating asthma, emphysema or bronchitis is 2.5-5 mg 3 times daily approximately 6 hours apart while awake. The maximum dosage is 15 mg/day. Shake the inhaler several times and uncap the mouthpiece. Breathe out fully. For best results, hold the inhaler 1 to 2 inches in front of your open mouth or attach a spacer to the inhaler and place the spacer in your mouth, above your tongue and past your teeth. Take a deep, slow breath as you push down on the canister. Hold your breath for 10 seconds, then exhale slowly. Use nebulizer machine for better response.

Dosages are adjusted to maintain serum theophylline concentrations that provide optimal relief of symptoms with minimal side effects. Most of the controlled release preparations may be administered every 12 hours in adults while administration every 8 hours may be necessary in some children with markedly rapid hepatic metabolism of theophylline. The recommended dosages for achieving serum theophylline concentrations within the accepted therapeutic range is as follow:

• 1-6 months: 10mg/Kg/day
• 6 months-1 year: 15mg/Kg/day
• 1-9 years: 24mg/Kg/day
• 10-16 years: 18mg/Kg/day
• Adults: 10-15mg/Kg/day

Side Effects

Dry mouth, irritated throat, nausea, dizziness, headache, heartburn, loss of appetite, altered taste sensation, restlessness, anxiety, nervousness, trembling, and sweating may occur but should subside as your body adjusts to the medication.

The following side effects have been observed:

Gastrointestinal: Nausea, vomiting, epigastric pain and diarrhoea.

Central nervous system: Headache, irritability, restlessness, insomnia, muscles twitching.

Cardiovascular: Palpitation, tachycardia, hypotension. circulatory failure.

Respiratory: Tachypnoea.Renal: Potentiation of diuresis.

Others: Alopecia, hyperglycemia, rash etc.

Toxicity

Patients experiencing an overdose may present with abdominal pain, agitation, palpitations, seizures, angina, hypertension, hypotension, tachycardia, arrhythmias, nervousness, headache, tremor, dry mouth, nausea, dizziness, fatigue, malaise, insomnia. Discontinue treatment with terbutaline and initiate symptomatic and supportive therapy.

Symptoms of overdose include seizures, arrhythmias, and GI effects.

Precaution

Before you use this drug, tell your doctor if you have: any allergies, heart disease, high blood pressure, an overactive thyroid gland, seizures, diabetes. Tell your doctor if you ever had a bad reaction to albuterol, bitolterol, ephedrine, epinephrine, isoetharine, isoproterenol, metaproterenol, pseudoephedrine, or pirbuterol or other similar agents. Tell your doctor if you are pregnant before using this medication. Terbutaline is excreted into breast milk. Consult with your doctor before breast-feeding. Terbutaline is not recommended for children under the age of 6. Caution is advised in the elderly.

Careful consideration is needed for various interacting drugs and physiologic conditions that can alter Theophylline clearance. Dosage adjustment is required prior to initiation of Theophylline therapy, prior to increases in Theophylline dose, and during follow up. The dose of Theophylline selected for initiation of therapy should be low and, if tolerated, increased slowly over a period of time.

Interaction

Tell your doctor of all nonprescription and prescription medications you take, including: beta-blockers (e.g., propranolol, timolol), all asthma drugs, antidepressants, MAO inhibitors (e.g., furazolidone, linezolid, phenelzine, selegiline, tranylcypromine), diuretics (e.g., hydrochlorothiazide). Many nonprescription medications contain pseudoephedrine or ephedrine, so check the labels carefully. Do not take any of these medications without consulting your doctor. Do not start or stop any medicine without doctor or pharmacist approval.

Allopurinol, cimetidine, norfloxacin, ciprofloxacin, erythromycin, oral contraceptives and propranolol increase serum theophylline levels. Phenytoin, methotrexate and rifampicin lead to decreased serum theophylline levels

Volume of Distribution

Terbutaline has a mean volume of distribution of 1.6 L/kg.

• 0.3 to 0.7 L/kg

Elimination Route

A 0.5 mg subcutaneous dose of terbutaline reaches a mean C_max of 9.6 ± ng/mL, with a median T_max of 0.5 hours, and a mean AUC of 29.4 ± 14.2 h*ng/mL. A 5 mg oral terbutaline tablet reaches a mean C_max of 8.3 ± 3.9 ng/mL with a median T_max of 2 hours, and a mean AUC of 54.6 ± 26.8 h*ng/mL. A 5 mg oral terbutaline solution reaches a mean C_max of 8.6 ± 3.6 ng/mL, with a median T_max of 1.5 hours, and a mean AUC of 53.1 ± 23.5 h*ng/mL.

Oral terbutaline has an oral bioavailability of 14-15%.

Theophylline is rapidly and completely absorbed after oral administration in solution or immediate-release solid oral dosage form.

Half Life

An oral dose of terbutaline has an elimination half life of 3.4 hours, while a subcutaneous dose has an elimination half life of 2.9 hours.

8 hours

Clearance

The average clearance of terbutaline is 3.0 mL/min/kg.

• 0.29 mL/kg/min [Premature neonates, postnatal age 3-15 days]
• 0.64 mL/kg/min [Premature neonates, postnatal age 25-57 days]
• 1.7 mL/kg/min [Children 1-4 years]
• 1.6 mL/kg/min [Children 4-12 years]
• 0.9 mL/kg/min [Children 13-15 years]
• 1.4 mL/kg/min [Children 16-17 years]
• 0.65 mL/kg/min [Adults (16-60 years), otherwise healthy non-smoking asthmatics]
• 0.41 mL/kg/min [Elderly (>60 years), non-smokers with normal cardiac, liver, and renal function]
• 0.33 mL/kg/min [Acute pulmonary edema]
• 0.54 mL/kg/min [COPD >60 years, stable, non-smoker >1 year]
• 0.48 mL/kg/min [COPD with cor pulmonale]
• 1.25 mL/kg/min [Cystic fibrosis (14-28 years)]
• 0.31 mL/kg/min [Liver disease cirrhosis]
• 0.35 mL/kg/min [acute hepatitis]
• 0.65 mL/kg/min [cholestasis]
• 0.47 mL/kg/min [Sepsis with multi-organ failure]
• 0.38 mL/kg/min [hypothyroid]
• 0.8 mL/kg/min [hyperthyroid]

Elimination Route

An oral dose of terbutaline is 40% eliminated in the urine after 72 hours. The major metabolite in the urine was the sulphate conjugated form of terbutaline. Parenteral doses of terbutaline are 90% eliminated in the urine, with approximately 2/3 as the unchanged parent drug. Less than 1% of a dose of terbutaline is eliminated in the feces.

Theophylline does not undergo any appreciable pre-systemic elimination, distributes freely into fat-free tissues and is extensively metabolized in the liver. Renal excretion of unchanged theophylline in neonates amounts to about 50% of the dose, compared to about 10% in children older than three months and in adults.

Pregnancy & Breastfeeding use

Although no teratogenic effects have been observed in animals or in patients, Terbutaline should only be administered with caution during the first trimester of pregnancy. Terbutaline is secreted via breast milk, but effect on the infant is unlikely at therapeutic doses.

Pregnancy: It is not known whether Theophylline can cause foetal harm when administered to pregnant woman.Xanthines should be given to a pregnant woman only if clearly needed.

Nursing mother: Theophylline is excreted into breast milk and may cause irritability or other signs of mild toxicity in nursing human infants. Serious adverse effects in the infant are unlikely unless the mother has toxic serum Theophylline concentrations.

Contraindication

Do not use Terbutaline if

• You are allergic to any ingredient in Terbutaline or to a sympathomimetic amine (eg, epinephrine, albuterol).
• You need to treat prolonged (more than 48 to 72 hours) premature labor.

Hypersensitivity to xanthine derivatives. It is also contraindicated in patients with active peptic ulcer disease and in individuals with underlying seizure disorders (unless receiving appropriate anti-convulsing medication).

Theophylline should not be administered concurrently with other xanthine. Use with caution in patients with hypoxemia, hypertension, or those with history of peptic ulcer. Do not attempt to maintain any dose that is not tolerated.

Special Warning

Terbutaline is not approved for use by children younger than 6 years of age.

Acute Overdose

Symptoms may include nausea, vomiting, gastrointestinal irritation, cramps, convulsions, tachycardia & hypotension. The stomach contents should be emptied & supportive measures employed to maintain circulation, respiration & fluid & electrolyte balance. Electrocardiographic monitoring should be carried out & in severe poisoning charcoal haemoperfusion should be used.

Storage Condition

Store at room temperature between 15 to 30° C. Keep away from moisture and sunlight. Do not puncture. Keep away from the reach of children.

Store in a cool and dry place, protect from light and moisture. Keep out of the reach of children

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