Health Articles

Metered-dose pdf

Q. What are metered-dose inhalers?
A. These are devices that dispense medicines directly into the lungs, in the form of a mist oraerosol in a specific dosage. In an MDI, themedicine is suspended in a liquid and forced underpressure into a small canister fitted into a plasticcase. When the canister is pressed, a measureddose of the medicine is released through themouth-piece.
Q. What are its different parts?
A. These are shown in the diagram on the front page.
Q. What are the advantages of MDIs over the
other modes of drug delivery in asthma
patients?
A. 1. Inhaled drugs are delivered directly into the 2. The drugs operate faster than when given orally.
3. Fewer side-effects occur as the dose is toosmall.
4. Inhaled drugs alleviate the distress experiencedby patients who do not like to receive injections.
Q. What are the steps for using an MDI?
A. 1. Remove the cap and hold the inhaler upright.
2. Shake the inhaler.
3. Tilt the head slightly and breathe out 4. Position the inhaler in one of the following (A) 2-4 cm away from the mouth, (B) inside the mouth.
5. Press down on inhaler to release medication as you start to breathe in slowly.
6. Breathe in slowly for 3 to 5 seconds.
7. Hold breath for at least 10 seconds to allow medicine to reach deeply into lungs.
8. Repeat puffs as directed. Waiting 1 minute between puffs, would permit the second puffto penetrate the lungs better.
Q. Which technique, the open-mouth or the
closed-mouth, is preferable?
A. Some doctors suggest that the technique of an inhaler held approximately 2 to 4 cm in front ofan open mouth, is superior to an MDI held in andactivated in a closed-mouth. The theoreticaladvantage of the open-mouth technique occursbecause the particles become significantlysmaller as they travel a distance from the activatedcanister orifice to the mouth. This enhances distal airway deposition. The disadvantage of the open-mouth technique is the problem of deposition onthe lips, face and teeth. Your doctor can help youdecide which method would be best for you.
Q. How can the patients to taught to correctly
use their MDIs?
A. Asthma patients usually think they are using their inhalers correctly, but their doctors don't agreewith them. In one study, the doctors estimated that,on an average, only about half of their patients,used their inhalers correctly. The patient's biggestchallenge is to coordinate the procedure ofpressing down on the inhaler and breathing in atthe correct moment.
As a rule, patients should have their inhalers withthem when they visit their doctor. The doctor canpersonally supervise its use and, if necessary,retrain the patient.
Q. Why is it so important to use MDI
A. MDI must be used correctly since only 10 percent of the inhaled dose penetrates the distal airways,even with optimal techniques.
For better penetration to distal airways, a slowdeep inhalation to total lung capacity is desirable.
It has been found that the particles are depositeduniformly throughout the lung with slowinhalation. The proportion of inhaled aerosolparticles remaining in the lung also increaseswith the time of breath-holding upto 10 seconds.
Q. Which anti-asthma drugs are available in the
form of MDI?
A. Many types of anti-asthma medication are available in the form of MDIs: Salbutamol, Formoterol, Beclomethesone,Fluticasone, Budesonide, Cyclesonide, etc. toname a few. They come under different brandnames. Combinations are also available.
Q. Which asthma patients need MDIs?
A. Patients with any type of asthma symptoms can make use of MDIs advantageously. Patients withmild symptoms may need only the MDI, whilepatients with moderate and severe symptomswould need it alongwith the help of other modesof drug delivery, such as tablets and / orinjections.
Q. When should a salbutamol MDI be used?
A. Salbutamol dilates the airways. Whenever there is a feeling that the airways are constricted,salbutamol MDI can be used. It is better for anasthma patient to fix the time for takingsalbutamol MDI, as for example, early morningwhen one gets up, and when going to bed at night.
Q. How many puffs of salbutamol a patient can
take in 24 hours?
A. If the airway constriction is only mild, two puffs in the morning and two in the evening are enough.
If the airway constriction is moderate, the doctor generally prescribes salbutamol MDIalong with other oral drugs so that the reliefobtained is adequate and spread over all the hoursof the day.
In moderate or severe asthma, if the symptoms are not relieved with 6 to 8 puffs of salbutamolin 24 hours, there is clear indication that adviceof the doctor be obtained. Using more puffs ofsalbutamol, not only would not provide adequaterelief, but the condition of the patient maydeteriorate and prove dangerous.
Q. What should be the interval between the two
puffs of salbutamol MDI?
A. An interval of 1 to 2 minutes should be there between the two puffs. The first puff takes thatmuch time to dilate the airways. The second puffafter this interval, penetrates the lungs furtherdown and so it is more effective.
Q. If both salbutamol and steroid MDIs are
prescribed, which one should be taken first?
A. Salbutamol should be taken first and after about 5 minutes of that, the steroid inhalation.
Salbutamol by dilating the bronchi, allows the steroid to penetrate the most peripheral parts ofthe lungs; this provides more relief.
Q. What does steroid MDI do when inhaled?
A. In an asthma patient, steroid inhalation relieves the inflamation in the lining of the airways.
However, this is a gradual process, not a quickone. The patient feels relief in hours, not inminutes. But it is longer lasting and it preventsthe permanent damage and the tendency toconstrict the airways.
If a patient has difficulty in breathing and wantsquick relief, he needs a bronchodilator likesalbutamol and not a steroid.
Q. What complications can occur because of
prolonged or excessive use of inhaled
steroids?
A. Inhaled corticosteroids are generally very safe.
In some patients, they can lead to formation ofwhite patches inside the mouth. This is the growthof the fungus called thrush or candida.
Q. How can the above complication be avoided?
A. By using steroid inhaler after passing it through a spacing device such as Spacehaler.
Rinsing the mouth clean with water, after having taken steroid inhalations, is also veryhelpful.
Q. How many puffs of steroid inhalation are
recommonded in 24 hours?
A. This depends on the severity of the disease and which type of steroid is being taken. But usually2 puffs of 200 ugm (microgram) twice or thricea day are recommended.
Q. How to check whether the inhaler is full, half
full or empty ?
A. 1. If the canister is new, it is full.
2. If the canister has been used repeatedly, itmight be empty (check product label to see howmany inhalations should be in each canister).
3. To check how much medicine is left in thecanister, put the canister (not the mouth-piece)in a cup of water. If the canister floats sidewayson the surface, it is empty, if it floats vertically,then it is full.

Source: http://www.acac.in/wp-content/uploads/publications/Metered-Dose_pdf.pdf