INHALATION THERAPY

Inhalation is an indispensable part in the standard treatment of acute and chronic diseases of the respiratory tract. Obstructive lung diseases are at the forefront, including asthma, chronic bronchitis and emphysema. By using proper medication, the increased mucous build-up in the respiratory tract as well as the constriction and inflammation of the mucous membrane can be diminished.

For a long time now, inhalation therapy has played a leading role: the medication can be directed to the source of the disease without detouring through the gastro-intestinal tract. The inhaler puts the medicine directly where it is needed, whereas oral tablets and syrups must be absorbed in the stomach and travel through the system before they reach the lungs, where they are needed. Thereby, side-effects of the medication are reduced, and in comparison to other means of treatment, only a fraction of the dosage is required.

A number of factors that influence the availability of inhaled drugs include:

• extent of airway inflammation

• degree of lung metabolism

• amount of drug swallowed and metabolized in the gastrointestinal tract

• patient’s ability to coordinate the release and inspiration of the medication

• type of drugs used

• delivery system (with the usage of spacer, inhaler is easier to manipulate and more drug reaches the lungs)

Three types of inhalers available in Malaysia are:

• Pressurised aerosol inhalers (Metered dose inhaler)

• Dry powder inhalers

• Respirator solution ( Jet Nebulizers )
  
  
  

METERED DOSE INHALER

Inhalation therapy comes in several forms, the most common of which is the pressurized metered dose inhaler (MDI), often called a puffer. MDI are small, portable devices that deliver medication in an aerosol form so it can be inhaled. They consist of a pressurized canister with a metering valve containing active drugs, low vapour pressure chloroflorocarbon (CFC) propellants, co-solvents and / or surfactants. The medication is dissolved or suspended in a liquid contained in a small canister. The canister fits into a plastic device, the mouth-piece, that releases a set amount of medication, or a metered dose.

MDI with spacer devices or holding chambers

An MDI is usually combined with a spacer or a holding chamber to have better compliance for patients with poor hand-lung coordination such as the elderly and children. Advantages of using spacers with an MDI are decreased oropharyngeal deposition and enhanced lung delivery. The purpose of a spacer is to allow evaporation of the propellant prior to inhalation. This allows inhalation after actuation of the devices, obviating the need for good hand-lung coordination and for a greater number of drug particles to achieve a respirable droplet size. Additionally, most of the large particles that would normally deposit in the oropharynx rain out in the spacer. This is an important factor in reducing local adverse effect (hoarseness, thrush).

DRY POWDER INHALERS

Dry micronized powders can be inhaled directly into the lung. A number of dry powder inhalers devices have been developed e.g RotahalerÒ , TurbohalerÒ and DiskhalerÒ . The RotahalerÒ requires a capsule of medication (Rotacap) to be placed in the back of the device. Then the device is twisted to open the capsules and release the medication for inhalation. The TurbohalerÒ and DiskhalerÒ are multidose devices which require ‘loading’ a dose prior to inhalation by twisting the grip and puncturing a blister of medication.

Diskaler	Diskaler
Rotahaler	Turbohaler
Figure 1: Types of dry powder inhalers

RESPIRATOR SOLUTION ( JET NEBULIZERS )

Respirator solutions are administered from a nebulizer both in hospital and general practice. Jet nebulizers are primarily used to deliver aerosols to hospitalized patients or patients with acute asthma exacerbations presenting to the clinic or emergency room. The nebulizers produces aerosol from the solution placed in a cup. They have the advantage of not requiring significant patient coordination or cooperation other than tidal breathing. Quiet tidal breathing through a mouth-piece or face-mask is the usual method of aerosol delivery from a nebulizer, however, slow deep inhalation and breath holding will also improve delivery from this devices as well as from an MDI. It is very important not to exceed the stated dose and if patient fails to respond to the usual dose of their respiratory solution they should call for help.


HOW TO USE

Proper use of an inhaler takes some practice. It is important to use the inhaler effectively in order to receive all drugs for the metered dose. If, through poor technique, a patient is not getting the entire prescribed dose, the effectiveness of the medication is difficult to determine.


Using an MDI inhaler

The following steps will teach you how to use an MDI correctly.

1. Remove cap from the mouthpiece. Shake the inhaler well to mix the medicine.

2. As stated below, there are 3 methods to use an MDI. Ask your doctor or pharmacist which method is best for you.

• Method 1: Hold the inhaler 1 to 2 inches in front of your mouth (about 2 to 3 finger widths ).

• Method 2: Using a spacer/holding chamber. Connect the spacer/ holding chamber to mouth. Close your lips loosely around the other end of the chamber. Do not block the opening with your teeth or tongue.

• Method 3: Put the mouthpiece of the inhaler in your mouth. Do not block the opening of the mouthpiece with your teeth or tongue.

3. Exhale ( breathe out ) slowly all the way.

4. Firmly press down on the inhaler as you inhale ( breathe in ) slowly ( 3 to 5 seconds ). This gives you one dose of medicine. Press your inhaler only 1 time while you are breathing in. If you use a holding chamber, first press down on the inhaler. Within 5 seconds, begin to breathe in slowly.

5. Take the mouthpiece away from your mouth. Hold your breath as you count to 10 slowly, if you can. This lets the medicine reach deeply into your lungs.

6. Exhale slowly. Never exhale through the mouthpiece.

7. Follow your doctor or pharmacist’s advice for the number of doses to take. If you need to take 2 doses, wait 1 minute before the next dose. Do not forget to shake the container again.

After using the inhaler

Rinse your mouth and gargle with water. This lessens the amount of medicine left in your mouth and throat. It also reduces the need to cough and keep you from getting a mouth infection.


How do I clean my inhaler?

Failure to clean the inhaler system properly may result in medication clogging the delivery system, which could lead to decrease in the dose delivered. Look at the hole where the medicine comes out from your inhaler. Clean the inhaler if you see "powder" in or around the hole. Remove the metal canister from the plastic mouthpiece. Rinse only the mouthpiece and cap in warm water. Allow to dry.


How do I know when my inhaler is empty?

Inhaler canister have the number of puffs listed on the canister. The example given below will explain on how to determined the content of your canister. If your canister has 200 puffs and you are told to take 8 puffs every day, divided 8 into 200. The answer is 25 (days). If you began using the inhaler May 1, replace it on/or before May 25. Write the date on the canister that you began using the medicine.

Another way to estimate the amount of medication left in inhaler can be done by putting the canister into water. Its position in the water will tell you how much inhalants remain (Figure 4).

Figure 4 : How much inhalant left in inhaler

CONCLUSION

The effectiveness of the inhaled drugs is optimized with proper usage of inhalers. So, it is extremely important to consult your doctor or pharmacist if there are any query regarding the techniques in using it.