You have been suffering from shortness of breath for few years and have been diagnosed asthma. You have been taking medicines and yet your symptoms worsen in cold or during a change in season. You feel incapacitated when you go short of breath. You seek immediate relief. Over a period, you have gained weight and developed a high blood sugar as you have been on medicines called steroids. Your doctor has now advised you to use a metered-dose inhaler (MDI). You should know how to use one to get the most of it.
Knowing about metered-dose inhalers
Metered-dose inhalers are hand held devices that are used to deliver the drug into the lungs via the mouth. The medicine is filled in a pressurized canister that fits into a boot shaped mouthpiece.
As metered-dose inhalers deliver the drug into the lungs, these are used for lung ailments like asthma or chronic obstructive lung disease (COPD). In these disorders, the air passages are narrowed or constricted. These can be used in a number of other lung diseases like an infection in the lung tissues or a raised pressure in the blood vessels of the lungs. Recently, these have been used to deliver many novel drugs in non-respiratory conditions like diabetes, pain, and some genetic disorders. The main utility is however in respiratory disorders and the metered-dose inhalers are used when there is a shortness of breath or difficulty in breathing.
Metered-dose inhalers can be routinely used to deliver the drug into the lungs. This is because they offer the advantage of a targeted drug delivery to the lungs where the medicine is required for local action. Since the medicine does not enter the blood, this route of drug delivery causes fewer side effects. In addition, it leads to a quick onset of action of the medicine. Metered-dose inhalers are portable, reliable, and cost effective.
Using a metered-dose inhaler correctly
A metered-dose inhaler should be used correctly in order to ensure that the right amount of medicine reaches the lungs. Read the instructions carefully on the inhalers and ask your pharmacist or doctor to demonstrate to you how to use it. It is simple to use the metered-dose inhalers. Follow all steps in series for efficient use. These steps are as under:
- Remove the cap from the MDI and shake it well.
- Breathe out completely
- Have the mouthpiece facing towards yourself, put it between the teeth and seal it around with your lips. You should firmly place your lips on the mouthpiece to prevent any air from escaping out through the mouth.
- Now slowly start breathing in and press down the canister for one time.
- Keep breathing in slowly and deeply and your breath can last up to 5 to 7 seconds.
- Now hold the breath for around 10 seconds to allow the medicine to reach the lungs.
- Repeat if you have been advised another puff.
- Recap the inhaler when you have taken all puffs.
Spacer
A spacer is an add-on device that provides a chamber to hold the medicine after you have pushed the canister down to release the drug. Spacers convert the released medicine into a mist. Spacers allow you to take another breath or two to completely inhale the medicine. Spacers are useful in children, elderly, or people who cannot time the spray with the inhalation or cannot hold breath for too long. Spacers prevent wastage of medicine as the mist is slowly, completely, and uniformly inhaled and not much of it is deposited on the back of the tongue or elsewhere in the mouth.
Propellants
MDIs contain propellants that give propel the drug and provide it momentum. The traditional MDIs contain CFCs (Chlorofluorocarbons) as propellants. These have been said to have a damaging effect on the ozone layer in the atmosphere of the earth. Many of these also contain alcohol. Recently, these are being increasingly replaced by those containing HFA (hydrofluoroalkane) propellant. This is chemically stable, safe, and meets the criteria for an ideal propellant described by the regulations. Hence, MDIs now contain CFC- and alcohol-free propellants.
Keeping track
You need to keep track of the amount of medicine you have used. Some inhalers have dose counters to facilitate the tracking and should be used only for the specified number of doses. Never use them for an additional dose even if some medicine remains the canister. Push down only once for one dose. It is not possible to determine if the inhaler is empty by simply shaking it. If your inhaler does not have a dose counter, you should keep a record of the doses used. Check the pack insert to see what is the number of doses contained in the inhaler. Depending upon the numbers of doses you need in one day, you can decide when you need to refill the inhaler and mark it on your calendar. Example, if your inhaler has 60 doses and you take 2 doses in a day, it implies that you should divide 60 by 2 and refill the inhaler after 30 days. If you use infrequent doses, you should note the date when you started to use the inhaler and then replace it as indicated on pack insert (3 to 4 months) or when you think it is no longer effective. Use a permanent marker to write the dates on your inhaler and on the calendar.
Conclusion
MDIs are patient friendly and easy to use. If used properly, these can help to make a difference to your illness and life and keep you away from lots of side effects. Befriend one and carry one with you always.
