Relievers
Relievers have a direct bronchodilator effect and relieve the symptoms of asthma. They are the mainstay drugs for the acute relief of asthma symptoms. Relievers are short-acting beta2 agonists (SABAs) and eformoterol, a long-acting beta2 agonist (LABA) with rapid onset of action.
Short-acting beta2 agonists
e.g. salbutamol (Airomir, Asmol, Epaq, Ventolin); terbutaline (Bricanyl)
(blue inhalers)
Short-acting beta2 agonists (SABAs) such as salbutamol and terbutaline relax bronchial smooth muscle by stimulating beta2-receptors, primarily in the airways, skeletal muscle and, to a lesser extent, the heart (this is especially important at higher doses). This accounts for adverse effects such as tachycardia and tremor.
SABAs treat the immediate symptoms of asthma, and can help to prevent exercise-induced asthma when used before exercise. They have no anti-inflammatory properties. They should be taken on an as-needed or on-demand basis, rather than regularly. Salbutamol and terbutaline will work within 5-15 minutes of inhalation.
Indications
- Acute relief of asthma symptoms
- Symptom relief during maintenance treatment of asthma
- Protection against exercise-induced asthma
Delivery
- Inhalation is the preferred method of delivery via a pressurised metered-dose inhaler (MDI), breath-activated inhaler or dry-powder inhaler (DPI).
- The onset of action is faster with inhalation and there are fewer adverse effects compared to other delivery methods.
- Delivery via an inhaler plus a spacer is as effective as nebulised therapy, with less time to deliver a dose and reduced equipment maintenance. See Acute asthma.
- Use a valved spacer for adults and older children, a spacer with an attached face-mask or mouthpiece for children aged 2-4 years and a large-volume spacer for children aged 5 years and over.
- Drug delivery via spacer is reduced by multiple actuations of the aerosol device. Optimal delivery is obtained by using one actuation at a time. This also allows for the recovery time of the valve mechanism. The static electricity charge on plastic spacers can also reduce delivery. This effect is reduced after initial use of the spacer device or by washing before first use and then at least every month; hand-wash in warm water with kitchen detergent without rinsing and allow to air-dry. Avoid storage in a plastic bag. Some, but not all spacers are dishwasher safe and cleaning should be in accordance with manufacturer's recommendations in each instance.
- Give the patient specific instructions about the dosage to be used for minor and acute exacerbations.
- Oral therapy with SABAs is discouraged in all age groups due to a slower onset of action and the higher incidence of behavioural side effects and sleep disturbance. It may have a limited role in the treatment of children under 2-3 years of age with mild occasional asthma.
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Short-acting beta2 agonists
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DOSAGE
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Metered-dose inhaler
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Salbutamol
100 mcg/inhalation, 1-2 inhalations as required every 3-6 hrs
For acute symptoms: 4-6 inhalations if < 6 yrs; 8-12 inhalations if > 6yrs;
if necessary repeat in 20 minutes
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Turbuhaler
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Terbutaline
500 mcg/inhalation, 1 inhalation as required every 3-6 hrs
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Autohaler
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Salbutamol
100 mcg/inhalation, 1-2 inhalations as required every 3-6 hrs
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Single-dose nebuliser units
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Salbutamol
Children 4-12 years: 2.5 mg unit every 3-6 hrs
Children > 12 years and adults: 5 mg unit every 3-6 hrs
Terbutaline
Children 4-12 years: 2.5 mg (1 mL) every 3-6 hrs
Children > 12 years and adults: 5 mg (2 mL) every 3-6 hrs
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Nebuliser solutions
should be diluted to 3-4 mLs with normal saline to overcome residual volume
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Salbutamol 5 mg/mL
Children: 0.03 mL/kg/dose to a maximum of 1 mL, diluted with saline to 4 mL, every 3-6 hrs
Adults: 1 mL every 3-6 hrs
Terbutaline
Children: 0.08 mL/kg/dose every 4-6 hrs
Adults: 1-2 mL/dose every 3-6 hrs
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Long-acting beta2 agonist with rapid onset
Eformoterol can be used as a reliever within the Symbicort maintenance and reliever regimen only. See Combination medications.
Content Created (Thursday, 16 November 2006)
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