Types of Metered Dose Inhalers
Metered dose inhalers are medications that are delivered directly to the lungs via inhalation. The inhalers consist of a small aerosol canister with or without a counter. There are several types that deliver a variety of medications to effectively treat many respiratory diseases, including asthma, COPD (chronic obstructive pulmonary disease), emphysema and chronic bronchitis.
Corticosteroids
Metered dose inhalers with corticosteroids control respiratory disease by suppressing overactive immune response in the lungs which can cause inflammation. Inflammation constricts airways and irritates the lungs, leading to spasms in the smooth muscles lining the lungs. Brand name metered dose inhalers include medications such as Flovent, Azmacort, Beclovent, Vanceril, Budesonide, Qvar and Aerobid. Do not discontinue use of corticosteroids without doctor supervision, as steroid dependency can develop resulting in withdrawal from abrupt discontinuation.
Bronchodilators
Metered dose bronchodilators relax the smooth muscles of the airways preventing spasms that restrict or cut off air supply. There are two types of bronchodilators: long and short acting. Serevent (salmeterol) and Foradil (formoterol) are long-acting bronchodilators taken twice a day and are used to prevent acute bronchospasm. Short-acting bronchodilators are used to treat acute bronchospasm and are often called "rescue inhalers." Brand names include Ventolin, Proventil, Maxair, Xopenex, Alupent and ProAir.
Combination Inhalers
Corticosteroids and long-acting bronchodilators have been combined into one metered dose inhaler for ease of use and efficacy. There is evidence that use of long-acting bronchodilators without an inhaled corticosteroid increases the risk of death during an asthma attack, which makes combination metered dose inhaler medications popular. Examples of brand name metered dose inhalers combining both a steroid and bronchodilator are Advair and Symbicort. Because of the corticosteroid component, these inhalers should not be discontinued suddenly.
Nonsteroidal Inhalers
Metered dose inhalers containing cromolyn (sold as Intal) or nedocromil (sold as Tilade or Alocril) are nonsteroidal medications that can prevent inflammation. These medications are used on a long-term basis to prevent asthma symptoms and must be taken daily. The exact mechanism of action for this type of metered dose inhaler is not well understood, but they seem to act by inhibiting the inflammation response in airways. In addition, because cromolyn has few side effects, it is often prescribed for children.
Proper Use
To use a metered dose inhaler, remove the cap and check to be sure the inhaler is clean and free of debris. Shake the inhaler to mix the medication. Exhale and place the inhaler just inside your mouth. Coordinate depression of the canister with inhalation and hold breath for 10 to 20 seconds. Exhale and wait one minute before administering another dose. Use spacers for breathing too impaired to properly coordinate inhalation. Rinse your mouth after using a metered dose inhaler containing corticosteroids to avoid thrush.
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