Asthma management

1. SABA (consider stepping up is using 3+ times/week)

2. Add low dose ICS

3. Initial add-on therapy: LABA

4. Additional controller therapies: increase ICS dose or add leukotriene receptor antagonist. If no response to LABA, consider stopping it

5. Regular oral corticosteroid (prednisolone). Refer patient for specialist care

Aims of mgmt = control of the disease. Complete control is defined as: no daytime Sx, no nighttime awakening due to asthma, no need for rescue medication, no asthma attacks, no limitations on activity (including exercise), normal lung function (in practical terms, FEV1 and PEFR > 80% predicted or best), minimal side effects from medication

Short acting beta-agonist e.g. salbutamol. Acts on adrenergic receptor to causesmooth muscle relaxation

1st line for all new asthma Dx. If being used 3+ times/week, consider stepping up treatment.

Acute bronchodilator effect, onset 5-30 mins, relief for 4-6hrs

Routs: inhalation of aerosol(MDI)/powder/nebulised solution, oral (tablet/solution), parenteral (IV/SC/IM injection)

Side effects minimised by inhaled delivery instead on systemic.

S/E: fine tremor, anxiety, headache, muscle cramps, palpitations, hypokalaemia, tachycardia, arrhythmias, peripheral vasodilation, myocardial ischaemia, sleep/behavioural disturbance

Long acting beta agonist e.g. salmeterol, formoterol

Chemical analogue on salbutamol with long lipophilic side-chain that anchors it in the lipid membrane to allow active portion to remain at receptor site- longer effect

Slower onset so not for use in relief of acute asthma attack

Acts on adrenergic receptor to cause smooth muscle relaxation

S/E: fine tremor, anxiety, headache, muscle cramps, palpitations, hypokalaemia, tachycardia, peripheral vasodilation, arrhythmias, myocardial ischaemia, sleep/behavioural disturbances

Long/short acting muscarinic antagonists e.g. ipratropium (SAMA), tiotropium (LAMA)

2nd line drugs (alternative/addition). Antagonise endogenous Ach at muscarinic (M3) receptors to relax bronchial smooth muscle and reduce mucus production

Useful in patients unable to take beta agonists (patients with IHD/tachycardia)

Generally reserved as an adjunct in acute severe asthma

Anticholinergic S/E: dry mouth, blurred vision, dizziness, tachycardia, hot flushed skin, agitation, urinary retention, constipation, delirium

2nd line drug (alternative/addition)

Inhibits phosphodiesterase so increases cAMP in smooth muscle cells -> activates PKA -> inhibits TNFa and leukotriene synthesis. Also reduces inflammation and innate immunity, and reverses steroid insensitivity.

Causes acute bronchodilation, may inhibit delayed phase reaction.

Usually administered orally for sustained release.

Narrow therapeutic index. Clarithromycin and ciprofloxacin inhibit metabolism so increase levels of theophylline.

Adverse effects: nausea, diarrhoea, tachycardia, headaches, insomnia, irritability, dizziness, arrhythmias

e.g. montelukast

Inhibit cysteinyl L1 receptor - only 1 pathway involved in asthma so less effective than steroids but also less side effects

Available orally (tablets)

Extensively metabolised- metabolites undergo biliary excretion.

Good for prophylaxis but not effective in acute asthma attacks

Inhibit phospholipase A2 and cyclooxygenase (both pathways involved in asthma)

Decrease inflammation and mucus production. 

Usually inhaled, can give oral corticosteroids in acute attacks

Adverse effects: oral candidiasis, hoarseness, easy bruising, wt gain, increased appetite, osteoporosis, iatrogenic adrenal suppression, gastritis/GI bleeds, cataracts, mood changes, sleep disturbance, insulin resistance/impaired glucose handling/diabetes

Omalizumab

Only used by specialist respiratory physicians in severe persistent confirmed IgE-mediated asthma needing continuous/frequent oral steroids (4+ courses/yr)