BRONCHODILATOR:

Bronchodilator drugs are drugs help to relieve breathing difficulties caused by asthma, bronchitis and bronchiolitis.Bronchodilators are medications commonly used by people with asthma. They relax the muscles that surround the airways and allow the airways (the tubes that carry air into and out of the lungs) to open up. Some bronchodilators act quickly to stop asthma symptoms (such as wheezing, coughing, or shortness of breath) that are often caused by narrowed airways. Known as rescue, quick-relief, or fast-acting medications, these bronchodilators are meant to be used when a person first notices symptoms, but their effect doesnt last long. Other bronchodilators, known as controller medications, are longer acting and are used to control, or prevent, asthma symptoms.Breathing difficulties include shortness of breath, coughing, rattling and wheezing, normally as a result of the narrowing of the bronchiole tubes. The tubes contract and the lining swells, narrowing the space for air to pass through. Tightness of the muscle surrounding the bronchioles, or a build up of excess mucus because of inflammation or infection is usually to blame.Broncholdilators cause the bronchioles to relax and widen; which makes breathing easier.

Bronchodilators are either short-acting or long-acting:

Short-acting medications provide quick or "rescue" relief from acute bronchoconstriction.

Long-acting bronchodilators help to control and prevent symptoms.

The three types of prescription bronchodilating drugs are:-

β2-agonists (short- and long-acting),

anticholinergics (short-acting), and 

theophylline (long-acting).

Short-acting β2-agonists

Long-acting β2-agonists

• Inhaled - Commonly taken twice a day with an anti-inflammatory medication, they maintain open airways and prevent asthma symptoms, particularly at night.
• Oral - Long-acting albuterol is available in pill or syrup form.

Theophylline

Available in oral and injectable form, theophylline is a long-acting bronchodilator that prevents asthma episodes. It belongs to the chemical class methyl xanthines . It is prescribed in severe cases of asthma or those that are difficult to control. It must be taken 1-4 times daily, and doses cannot be missed.. Side-effects can include nausea, vomiting, diarrhea, stomach or headache, rapid or irregular heart beat, muscle cramps, nervous or jittery feelings, and hyperactivity. Coffee, tea, colas, cigarette-smoking, and viral illnesses can all affect the action of theophylline and change its effectiveness.

How does it works:

Bronchodilators are inhaled directly into the lungs using:

§ Inhalers (puffers) - plastic devices that release a small dose of the required drug when inhaled. Can be used whenever necessary to relieve an attack, or on a regular basis to prevent an attack occurring. Usually improves breathing after a few minutes. Some people take an extra dose

• before activity that is likely to cause breathlessness (eg exercise) to prevent an attack. Inhaled corticosteroids are usually effective in a few days and often reduce the frequency of attacks.
• Insufflation cartridges - deliver a larger dose than inhalers, and
• Nebulizers - deliver the largest dose and rapid relief. A mixture of compressed air and the drug is given using a face mask

Side Effects:

 Bronchodilators do not usually cause any serious side effects, but the following are known to occur in some cases:Anticholinergics, dry mouth,blurred vision, difficulty urinatingSympathomimetic, heart flutter (palpatations)Trembling, Xanthine,headachesnausea.