Salbutamol

Oral
Bronchospasm
Adult: Treatment and prevention in patient with reversible obstructive airway disease: As syr/immediate-release tab: 2-4 mg 3-4 times daily, may be increased up to max 8 mg 3-4 times daily as tolerated. As extended-release tab: 4-8 mg 12 hourly.
Child: As syr/immediate-release tab: 2-6 years 1-2 mg; >6-12 years 2 mg; >12 years Same as adult dose. All doses are given 3 or 4 times daily. As extended-release tab: 6-12 years 4 mg 12 hourly.
Elderly: As syr/immediate-release tab: Initially, 2 mg 3 or 4 times daily.

Inhalation
Acute bronchospasm
Adult: Treatment and prevention in patient with reversible obstructive airway disease: As metered-dose aerosol or dry powder inhaler (90 or 100 mcg/actuation): 1 or 2 inhalations every 4-6 hours. Max: 800 mcg daily.
Child: As metered-dose aerosol or dry powder inhaler: 4-11 years 1 or 2 inhalations; ≥12 years Same as adult dose.

Parenteral
Severe bronchospasm
Adult: 50 mcg given via SC or IM injection given 4 hourly, as required.
Child: ≥12 years Same as adult dose.

Intravenous
Uncomplicated premature labour
Adult: For arrest of preterm labour between 22 and 37 weeks of gestation: Initially, 10 mcg/min, increased at 10-minute intervals until there is response; then increase infusion rate slowly until contractions cease. Usual dose: 10-45 mcg/min. Maintain infusion at rate at which contractions stop for 1 hour, then reduce by decrements of 50% at intervals of 6 hours. Max treatment duration: 48 hours.
Reconstitution: IV: Dilute ampoule labelled as containing 500 mcg/mL with 10 mL of water for injection to provide a solution containing 50 mcg/mL; or dilute 5 mL salbutamol inj with 500 mL NaCl or dextrose inj to a concentration of 10 mcg/mL. Use within 24 hours.

Intravenous
Severe bronchospasm
Adult: As 50 mcg/mL solution: 250 mcg (4 mcg/kg) via slow inj. May be repeated if necessary. As 10mcg/mL solution via infusion: Usual rate of 3-20 mcg/min, adjusted according to patient needs.
Child: ≥12 years Same as adult dose.
Reconstitution: IV: Dilute ampoule labelled as containing 500 mcg/mL with 10 mL of water for injection to provide a solution containing 50 mcg/mL; or dilute 5 mL salbutamol inj with 500 mL NaCl or dextrose inj to a concentration of 10 mcg/mL. Use within 24 hours

Inhalation
Prophylaxis of exercise-induced bronchospasm
Adult: As metered-dose aerosol or dry powder inhaler (90 or 100 mcg/actuation): 2 inhalations 15-30 minutes prior to exercise.
Child: As metered-dose aerosol or dry powder inhaler (90 or 100 mcg/actuation): 4-11 years 1 or 2 inhalations 15-30 minutes prior to exercise; ≥12 years Same as adult dose.

Inhalation
Chronic bronchospasm
Adult: Via nebuliser: 2.5-5 mg up to 3-4 times daily.
Child: ≥4 years Same as adult dose.

IV (in the treatment of premature labour): Pre-existing or risk factors for ischaemic heart disease, gestational age <22 week, conditions in which prolongation of pregnancy is hazardous, intrauterine foetal death, known lethal congenital or lethal chromosomal malformation, pulmonary hypertension. Non-IV formulation is not indicated for use in uncomplicated premature labour or threatened abortion.

Patient with CV disease (e.g. arrythmia, coronary insufficiency, hypertension, heart failure), diabetes mellitus, glaucoma, hyperthyroidism, hypokalaemia, seizures. Renal impairment. Children and elderly. Pregnancy and lactation. Monitoring Parameters Monitor FEV₁ peak flow, and/or other pulmonary function tests; blood pressure, heart rate, CNS stimulation; serum glucose, K and creatinine; asthma symptoms; arterial or capillary blood gases if needed; lactate, and ECG (IV).

Significant: Hypersensitivity reactions (e.g. urticaria, angioedema, rash, bronchospasm, oropharyngeal oedema), hypokalaemia (high doses). Cardiac disorders: Tachycardia, palpitations, chest pain. Rarely, cardiac arrythmias (e.g. atrial fibrillation, supraventricular tachycardia, extrasystoles), myocardial ischaemia. Gastrointestinal disorders: Nausea, vomiting, mouth and throat irritation (inhalation). General disorders and administration site conditions: Weakness. Metabolism and nutrition disorders: Hyperglycaemia. Rarely, lactic acidosis (high doses). Musculoskeletal and connective tissue disorders: Muscle cramps. Nervous system disorders: Tremor, headache, dizziness, drowsiness, restlessness. Psychiatric disorders: Nervousness, irritability, insomnia. Respiratory, thoracic and mediastinal disorders: Pharyngitis, rhinitis, pulmonary oedema (parenteral). Vascular disorders: Peripheral vasodilation, flushing.
Potentially Fatal: Rarely, paradoxical bronchospasm.

Symptoms: Tachycardia, tremor, hyperactivity, metabolic effects (e.g. hypokalaemia, lactic acidosis), headache, nervousness, dry mouth, palpitations, dizziness, fatigue, malaise, insomnia, arrhythmias, anginal pain, seizures. Children may experience nausea, vomiting, hyperglycaemia when taken orally. Management: Symptomatic treatment. Monitor serum K and lactate levels. May give cardioselective β-blocker with caution. May give oral or IV potassium for hypokalaemia as needed.

Increased risk of hypokalaemia with corticosteroids, diuretics (e.g. loop, thiazide) and xanthines (e.g. theophylline). Increased vascular effects with MAOIs, tricyclic antidepressants (TCAs). May cause severe bronchospasm when used with β-blockers (e.g. propranolol). May decrease serum concentrations of digoxin.

Salbutamol is a direct-acting sympathomimetic that acts on β₂-receptors to relax bronchial smooth muscle with less prominent effect on the heart. It activates adenyl cyclase, the enzyme that stimulates the production of cyclic adenosine-3', 5'-monophosphate (cAMP). Increased cAMP leads to activation of protein kinase A, which inhibits phosphorylation of myosin and lowers intracellular ionic Ca concentrations, resulting in muscle relaxation. Synonym: albuterol
Onset: ≤5 minutes (inhalation); 5.4-8.2 minutes (oral inhalation); ≤30 minutes (oral).
Duration: Inhalation: 3-6 hours. Oral inhalation: Approx 2-6 hours. Oral: 6-8 hours (immediate-release); up to 12 hours (extended-release).
Absorption: Readily absorbed from the gastrointestinal tract. Time to peak plasma concentration: Inhalation: 30 minutes. Oral inhalation: 25-30 minutes. Oral: ≤2 hours (immediate-release); 6 hours (extended release). Bioavailability: Approx 50%.
Distribution: Crosses the placenta. Plasma protein binding: 10%.
Metabolism: Metabolised in the liver to an inactive sulfate conjugate.
Excretion: Mainly via urine (80-100% [oral inhalation]; 76% over 3 days, [60% as metabolite; oral]); faeces (<20% [oral inhalation]; 4% [oral]). Elimination half-life: Oral inhalation: 3.8 to approx 5 hours. Oral: 5-6 hours (immediate-release); 9.3 hours (extended-release). IV: 4-6 hours.

Inhalation: Dry powder or metered dose inhalers: Store below 25°C. Intravenous: Solution for inj: Store below 30°C. Protect from light. Oral: Tab/syr: Store below 25°C. Parenteral: Solution for inj: Store below 30°C. Protect from light.

Antiasthmatic & COPD Preparations / Drugs Acting on the Uterus

R03AC02 - salbutamol ; Belongs to the class of adrenergic inhalants, selective beta-2-adrenoreceptor agonists. Used in the treatment of obstructive airway diseases.
R03CC02 - salbutamol ; Belongs to the class of adrenergics for systemic use, selective beta-2-adrenoreceptor agonists. Used in the treatment of obstructive airway diseases.