Salbutamol

Bronchial asthma: Salbutamol causes relaxation of smooth muscle in the bronchial tree to allow dilatation of the airways. It may also have a role in stabilizing mast cells in the mucosa which release mediators that contribute to bronchospasm. The effect of salbutamol can be assessed by measuring the peak flow rate with a special meter. Short-acting beta2 agonists should not be prescribed for use on a regular basis in patients with mild or moderate asthma since regular treatment provides no clinical benefit. Longer acting beta2 agonists, (eg. salmeterol) are of benefit when taken regularly. The activation of β;;2-receptors results in relaxation of uterine smooth muscle, thus delaying labour (tocolysis). It is used to treat severe hyperkalaemia.

COPD: Salbutamol causes relaxation of smooth muscle in the bronchial tree to allow dilatation of the airways. The effect of salbutamol can be assessed by measuring the peak flow rate with a special meter. Short-acting beta2 agonists are given initially either alone or with an anti-muscarinic (ipratropium). Longer acting beta2 agonists, (eg. salmeterol) are of benefit for more chronic symptoms.

Bronchial asthma: Side-effects of the salbutamol (and other beta2 agonists) include fine tremor (particularly in the hands), nervous tension, headache, muscle cramps, and palpitations. Other side-effects include tachycardia and arrhythmias and disturbances of sleep and behaviour in children. Paradoxical bronchospasm, urticaria, and angioedema have also been reported. Beta2 agonists are associated with hypokalaemia after high doses and this effect is employed in the emergency management of hyperkalaemia (in addition to insulin/dextrose).

COPD: Side-effects of the salbutamol (and other beta2 agonists) include fine tremor (particularly in the hands), nervous tension, headache, muscle cramps, and palpitations. Other side-effects include tachycardia and arrhythmias. Paradoxical bronchospasm, urticaria, and angioedema have also been reported. Beta2 agonists are associated with hypokalaemia after high doses.

Bronchial asthma: Salbutamol is normally delivered by inhalation directly into the bronchial tree which maximises its exposure at the site of action and minimises systemic absorption which leads to undesirable side-effects. Aerosol inhalation is commonest with the inhaler typically delivering 100 micrograms/puff and 2 puffs taken up to 4 times per day. It may be taken prophylactically in the case of exercise-induced asthma. Use of aerosol inhalers requires careful coordination with breathing about which the patient requires instruction. Those who find this difficult (eg. children) may benefit from a 'spacer' device into which the aerosol is puffed before inhalation. Salbutamol may also be inhaled in powder form. Inhalation of 2.5-5mg as a nebulised solution up to 4 times daily is typical in severe attacks. Nebuliser solutions of salbutamol are used for the treatment of acute asthma in hospital or in general practice. Patients with a severe attack of asthma should preferably have oxygen during nebulisation since beta2 agonists can increase arterial hypoxaemia. The dose given by nebuliser is substantially higher than that given by inhaler. Patients with their own nebuliser should therefore be warned that it is dangerous to exceed the prescribed dose and they should seek medical advice if they fail to respond to the usual dose of the respirator solution. Salbutamol can also be delivered by mouth, subcutaneously, IM and IV although all of these routes are associated with a greater incidence of systemic effects.

COPD: Salbutamol can be delivered inhalation directly into the bronchial tree which maximises its exposure at the site of action and minimises systemic absorption which leads to undesirable side-effects. Aerosol inhalation is commonest with the metered-dose inhaler (MDI) typically delivering 100 micrograms/puff and 2 puffs taken up to 4 times per day. Use of aerosol inhalers requires careful coordination with breathing about which the patient requires instruction. Those who find this difficult (eg. children) may benefit from a 'spacer' device into which the aerosol is puffed before inhalation. Salbutamol may also be inhaled in the form of dry powder cartridges. Inhalation of 2.5-5mg as a nebulised solution up to 4 times daily is typical in severe attacks. Nebuliser solutions of salbutamol are used for the treatment of acute exacerbations of COPD in hospital or in general practice. The dose given by nebuliser is substantially higher than that given by inhaler. Patients with their own nebuliser should therefore be warned that it is dangerous to exceed the prescribed dose and they should seek medical advice if they fail to respond to the usual dose of the respirator solution. Salbutamol can also be delivered by mouth, subcutaneously, IM and IV although all of these routes are associated with a greater incidence of systemic effects.

Bronchial asthma: See eBNF.

COPD: See eBNF.

Bronchial asthma: OTHER BETA-2 AGONISTS. Terbutaline is another short-acting beta2 agonist similar to salbutamol that is used by inhalation in mild to moderate asthma. Salmeterol and formoterol (eformoterol) are longer-acting beta2 agonists which are administered by inhalation. They should not be used for the relief of an acute asthma attack. Salmeterol and formoterol should be added to existing corticosteroid therapy and not replace it. They can be useful in nocturnal asthma. Patients with asthma who use salmeterol must also use an inhaled corticosteroid because salmeterol may increase life-threatening attacks when given without an inhaled corticosteroid. OTHER BRONCHODILATOR DRUGS. Other beta-2 adrenoceptor agonists (eg. terbutaline, salmeterol, formoterol). Other adrenoreceptor agonists including adrenaline (epinephrine) injection (1 in 1000) which has both alpha- and beta-adrenoceptor agonist properties and is used in the emergency management of allergic and anaphylactic reactions and in the management of croup. Antimuscarinic bronchodilators (eg. ipratropium, tiotropium). Theophyllines (eg. theophylline, aminophylline). MANAGEMENT OF ACUTE ASTHMA. Oxygen. Beta-2 agonist (eg. nebulised salbutamol). Corticosteroid (eg. oral prednisolone or IV hydrocortisone). Admission to hospital in more severe cases. Additional measures might include nebulised ipratropium, intravenous aminophylline and admission to intensive care for mechanical ventilation.

COPD: MANAGEMENT OF COPD. Chronic obstructive pulmonary disease may be treated initially with an inhaled short-acting beta-2 agonist (eg. salbutamol) or a short-acting antimuscarinic bronchodilator (eg. ipratropium) used as required. When the airways obstruction is more severe, a regular inhaled antimuscarinic bronchodilator (eg. ipratropium) should be added. In those who remain symptomatic or have two or more exacerbations in a year, a long-acting beta-2 agonist should be added (eg. salmeterol). If symptoms persist despite a trial of short-acting bronchodilators or a long-acting beta-2 agonist or a long-acting antimuscarinic bronchodilator (eg. tiotropium) or if the patient is unable to use inhaled therapy, theophylline can be used. In moderate or severe chronic obstructive pulmonary disease, a combination of a long-acting beta-2 agonist and an inhaled corticosteroid (eg. beclametasone) should be tried. Combination treatment should be discontinued if there is no benefit after 4 weeks. Long-term oxygen therapy prolongs survival in patients with severe chronic obstructive pulmonary disease and hypoxaemia. MANAGEMENT OF COPD EXACERBATIONS. Bronchodilator therapy (eg. salbutamol, ipratropium, or both) can be administered through a nebuliser if necessary and oxygen given if appropriate. A short course of oral corticosteroid should be given if increased breathlessness interferes with daily activities. Antibacterial treatment is required when the sputum becomes purulent or if there are other signs of infection.