Asthma is a chronic airway disorder characterized by variable and recurring airflow obstruction and sudden constriction of the muscles of the bronchioles (bronchospasms). Other symptoms may be wheezing, coughing and shortness of breath. Patients can experience sudden episodes of acute asthma (exacerbations).

The underlying mechanism of asthma is a chronic inflammation of the airways caused by allergic or non-allergic stimuli. Allergic asthma is mediated by immunoglobulin E (IgE) and mast cells and can be triggered by dust mites, fungi, certain foods and pollen. Non-allergic asthma is mediated by interleukins and eosinophils and can be triggered by viral infections, physical exercise, changes in humidity or temperature and air pollution.

Current treatment

Currently there is no cure for asthma. Treatment is focused on improving symptoms (less than two asthma attacks per week) and quality of life. Non-medical measures patients can take are regular exercising and avoiding stimuli that can trigger an asthma attack.

When the symptoms are not under control with these measures, the patient starts with medical treatment. This can be divided into four different steps:

1.       As needed SABA or low-dose ICS/LABA

2.       Daily dose ICS

3.       Daily dose ICS/LABA

4.       High or intermediate dose ICS/LABA

Medical treatment starts with step one and is intensified until the asthma is under control. SABA’s and LABA’s are symptom relievers and cause rapid dilatation of the bronchioles. They are used during an acute asthma attack. ICS inhibit the underlying inflammation and prevent an asthma attack from taking place. They are used as a maintenance therapy. For more information about these drugs, check out trc-p.nl.

SABA’s, LABA’s and corticosteroids are administered via inhalation. This causes the drugs to have a fast onset of action because they quickly reach the site of action. Systemic side-effects are also minimalized because of the local application and slight adsorption. 

SABA     = short acting beta-2 agonist

LABA      = long acting beta-2 agonist

ICS          = inhalation corticosteroids

Neurokinine-antagonist

Tachykinins are neuropeptides that exert their effect on the neurokinin (Nk) receptors. There are many tackykinins, but substance P and neurokinin A (NkA) are the only ones found in the respiratory system. Substance P and NkA are released by sensatory nerves after stimulation by exogenous substances like inhaled irritants and by endogenous substances, such as inflammatory mediators. Substance P and NkA can activate the Nk1 and Nk2 receptors which in turn can cause bronchoconstriction and mucous secretion in the airways. Tachykinins also have immunomodulatory effects. They play a role in the expression of adhesion molecules on endothelial cells and lymphocytes and can activate mast cells.