Salbutamol

Salbutamol is a beta2-adrenergic receptor belonging to bronchodilator.

Salbutamol is used in the treatment of asthma, bronchitis, COPD, emphysema, pulmonary fibrosis, and other respiratory conditions.

Salbutamol is Readily absorbed from the gastrointestinal tract withbioavailability of Approx 50% and Crosses the placenta. Plasma protein binding: 10%.

It get metabolized in the liver to an inactive sulfate conjugate and get excreted 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.

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).

The Tmax of salbutamol is about 2 hours.

The Cmax of salbutamol in plasma is 0.5 μg/L.

Salbutamol shows common side effects like insomnia, confusion, hallucination, nervousness, disorientation, depression, anxiety, mood changes. Renal and urinary disorders: Crystalluria (high doses).

Salbutamol is available in inhalation aerosol, metered dose inhaler, dry powder inhaler

Salbutamol is available in India, Germany, Canada, France.

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.

Salbutamol is available in the form of inhalation aerosol, metered dose inhaler, dry powder inhaler.

Salbutamol is used in the treatment of asthma, bronchitis, COPD, emphysema, pulmonary fibrosis, and other respiratory conditions.

Salbutamol is a short-acting beta-2 adrenergic receptor agonist used in the treatment of bronchospasm associated with asthma and chronic obstructive pulmonary disease (COPD), as well as other lung conditions such as bronchiolitis and exercise-induced bronchospasm. It works by relaxing the smooth muscles in the airways, making it easier to breathe.

Salbutamol is approved for use in the following clinical indications Asthma, Bronchitis, COPD, Emphysema, Pulmonary fibrosis, and other Respiratory conditions.

Inhalation/Respiratory

• 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.

Inhalation/Respiratory

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/Respiratory

Chronic bronchospasm

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

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.

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.

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.

Parenteral

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

Salbutamol is available in various strengths as 2.5, 10 mg

Salbutamol is available in the form of inhalation aerosol, metered dose inhaler, dry powder inhaler.

Dosage Adjustment in Kidney Patient

• eGFR ≥30 mL/minute/1.73 m2: No dosage adjustment necessary.
• eGFR ≤30 mL/minute/1.73 m2: 400 mg once daily.

Dosage Adjustment in Hepatic impairment Patient

● No Dosage Adjustment is necessary .

Dosage Adjustment for Pediatric Patients

No Dose Adjustment is necessary

Dosing: Kidney Impairment:

Pediatric

• Adolescents ≥17 years:
• CrCl ≥30 mL/minute: No dosage adjustment necessary.
• CrCl <30 mL/minute: Initial: 0.5 mg once daily; maximum maintenance dose: 0.5 mg twice daily.
• End-stage renal disease (ESRD) (receiving hemodialysis): Maximum maintenance dose: 0.5 mg once daily.

Take after eating and with a full glass of water to decrease gastric upset.

IV (in the treatment of premature labour): Pre-existing or risk factors for ischaemic heart disease, gestational age <22 weeks, 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.

Bronchodilators in patients with serious or unstable asthma should not be the only or the primary treatment. As patients are at risk of serious attacks and even death, severe asthma requires a routine medical examination, including lung function monitoring. In these patients, physicians should consider the use of oral corticosteroid therapy and/or the maximum recommended inhaled corticosteroid dose. Severe photo toxicity reactions. Discontinue use if photosensitivity occurs.

Salbutamol may cause liver problems, and using it with substantial quantities of ethanol may increase that risk.

Pregnancy Category C

There are no controlled studies in pregnant women. Salbutamol should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Oral formulations should be administered on an empty stomach with water (at least 1 hour before or 2 hours after meals, milk, or other dairy products). Maintain fluid intake to ensure adequate hydration and urinary output.

• Common Adverse effects

The most common side effects of salbutamol are:

Headache, Feeling shaky or anxious, Fast or irregular heartbeat, Difficulty sleeping, A dry mouth or throat, Nausea, Vomiting, Diarrhea, A rash, Chest pain, Difficulty breathing, An increase in the number of colds or infections.

• Less Common Adverse effects:

Restlessness, Anxiety, Cough, Sore throat, Chest pain, Depression, Suicidal thoughts

• Rare Adverse effects

Insomnia, Confusion, Hallucination, Nervousness, Disorientation, Depression, Anxiety, Mood changes. Renal and urinary disorders: Crystalluria (high doses).

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.

The common side effects of Salbutamol include the following :tremors, headache, palpitations, and nervousness.

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.

Pharmacodynamic

Salbutamol is a short-acting beta-2 adrenergic receptor agonist used in the treatment of bronchospasm associated with asthma and chronic obstructive pulmonary disease (COPD), as well as other lung conditions such as bronchiolitis and exercise-induced bronchospasm. It works by relaxing the smooth muscles in the airways, making it easier to breathe.

Pharmacokinetics

• 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.

1. https://pubmed.ncbi.nlm.nih.gov/1091001/
2. https://clinicaltrials.gov/ct2/show/NCT01422915
3. https://clinicaltrials.gov/ct2/show/NCT02263547
4. https://www.medicines.org.uk/emc/product/128/smpc.

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1364710/
2. https://reference.medscape.com/drug/colestid-Salbutamol -342452
3. https://go.drugbank.com/drugs/DB00375
4. https://www.sciencedirect.com/topics/medicine-and-dentistry/Salbutamol
5. https://europepmc.org/article/med/6988203