Salbutamol Flashcards
What class of drugs does Salbutamol belong to?
bronchospasm relaxants
what are other drugs in the same class as salbutamol?
salmeterol terbutaline aminophylline theophylline adrenaline
What is the mechanism of action of salbutamol?
acts on β2-adrenoreceptors in bronchi and uterus, resulting in bronchodilatation and reduced uterine contractility with little or no action on β1-adrenoreceptors of the heart.
What its salbutamol indicated for?
Bronchodilator for the relief of symptoms during maintenance treatment of Asthma and COPD
Prevention of allergen or EIB, acute asthma, premature labour
What is the dose of salbutamol given?
Symptom relief:
Inhalation- 100-200μg prn, Max qid (adult)
Oral- 2-4mg 3-4x/day max 8mg qid (adult)
Acute symptoms:
Inhalation - 600μg (6 puffs) each inhaled separately. Repeat at 10-20 minute intervals if necessary max 6 times. (adult)
Nebuliser- 2.5-5mg up to qid. Up to 40mg/day may be given in hospital for severe airways obstruction (adult)
Prevention of allergy or EIB:
Inhalation- 200μg (adult)
Acute asthma- severe bronchospasm
SC or M injection- 500μ repeated q4h if necessary (adult)
Slow IV injection- initially 5μg/min, adjusted according to response and hart rate. Usually 3-20μg/min
What are the main PK and PD parameters regarding Salbutamol?
PD: Salbutamol is a selective β2 adrenoreceptor agonist, acting on bronchial muscle to provide short acting bronchodilation with fast onset (within 5 minutes), when given therapeutic doses
PK:
half life of 4-6 hours
Cleared partly renally, partly by metabolism to inactive phenolic sulphate (excreted primarily in urine)
10% bound to plasma proteins
What are the precautions regarding salbutamol?
hyperthyroidism, CVD, arrhythmias, susceptibility to Q-T elongation, hypertension, diabetes (risk of ketoacidosis, esp. if given IV) Hypokalaemia
What are the contraindications regarding salbutamol?
-patients with history of hypersensitivity to any of its components
however for the use in labour, (oral form)
contraindications include:
treatment of threatened abortion
elixir
obstetrics including management of prematurelabour
What are the adverse reactions of salbutamol?
fine tremor, particularly in hands nervous tension headache muscle cramps palpitation tachycardia arrhythmias, peripheral vasodilation myocardial ischaemia disturbances of sleep and behaviour hypokalaemia
What are the drug interactions with salbutamol?
Antivirals: risk of ventricular arryhtmias
Cardiac glycosides: reduces plasma concentration of digoxin
Corticosteroids: increased risk of hypokalaemia
Diuretics: Increased risk of hypokalaemia (incl. acetazolamide, loop diuretics or thiazides and related diuretics
Methyldopa: acute hypotension reported
Theophylline: increased risk of hypokalaemia
What are the alarm bells associated with salbutamol use?
potentiall serious hypokalaemia may result from β2 agonist therapy.
Take particular caution in severe asthma as this may be potentiated by concomitant treatment with theophylline and derivatives, corticosteroids and diuretics, and by hypoxia.
What monitoring is involved in salbutamol use?
Plasma potassium concentration
