Even though the history of modern day
inhalers is relatively recent, human beings are known to use inhalation of
smokes of herbal drugs for relief from coughs for centuries. Fumes of different
herbs had been used in India, China, Egypt and Greece for long before the
Christian era. Indians used fumes of
stramonium and hemp while the Egyptian produced vapours of black henbane by
heating the weed on hot bricks. Dhatura
continued to be smoked for its cough relieving properties practically
throughout the past five millennia in most of the ancient cultures in the
world. Inhalation has been also popular
to get a kick from habituating drugs. Today, inhalational treatment constitutes
the corner-stone of therapy for asthma and other respiratory disorders.
There are numerous misgivings about
inhalational treatment. Essentially speaking, inhalation is only a method of
drug-delivery. It is not a treatment in itself. There are a number of drugs
which can be used as inhalational drugs. Respiratory diseases such as asthma
and chronic obstructive pulmonary disease (COPD) are the most common diseases
for which inhalational treatment is preferred. The inhalational route is also
employed sometimes for certain types of cough, infections and other diseases.
Inhaler Therapy
Treatment for asthma is best
administered in the form of inhalers.
Contrary to the general belief that inhalers are better reserved for
non-responsive or severe asthma, they are used ideally as the first line of therapy.
Use of inhalers
for asthma can be compared to using ointments for skin diseases and eye drops
for eye condition. Inhaler medications deliver the drug to the site of the
disease. Therefore:
- The effect is almost instantaneous
- Dose required is about one tenth of the tablet or a capsule
- Side effects are negligible.
Fortunately, most
of the drugs used both to relieve symptoms of asthma (relievers) and to control
the disease (controllers) are now available as inhalers.
Some myths about inhalers
- Costlier
- Difficult to understand the proper use
- Addicting in nature
i.
Costs: Although the initial cost
of the drug in an inhaler (compared to a tablet) is higher, in the long run an
inhaler drug works out to be more economical.
Better control of asthma reduces the periods of absence from work or
school. Furthermore, all the expensive
hospital bills of poorly controlled asthma are saved.
ii.
Difficulties to
use:
Proper use of inhalers requires good understanding of the
technique. It is especially challenging
to the elderly and small children. With
time and patience (for both the doctor and the User) proper use of inhalers can
be explained well to ensure their effective use.
Incorrect use is the most
common reason for poor response to inhalers.
iii.
Addicting in nature: There
is no true addiction to inhalers. Inhalers are not drugs but the method of
using a drug. Anti-asthma drugs used in inhalers are non-addicting, purely for
relief and control of asthma. Sometimes,
an individual keeps on using puffs of inhalers to get relief from symptoms.
This type of ‘addiction’ must be avoided. One should consult the doctor if the
need for use of inhalers increases. Additional treatment may be required.
Types of inhalers
There are two types of inhalers in
use:
- Metered Dose Inhalers (MDI)
- Dry Powder Inhalers (DPI)
Besides inhalers, nebulization is also a method of drug-administration
in an inhalational form.
Many drugs are also available as
‘nebulizing solutions’ for use with a nebulizer. Nebulizer is a compressor driven machine that
breaks the drug solution into a vaporized form of fine particles Nebulization
is used for severe attacks when inhalers are difficult to use or in case of children
and the elderly who have problems coordinating the use of inhalers.
Metered Dose
Inhalers (MDI): An MDI contains drug in a liquid state inside
a pressurized canister. With each
actuation of the inhaler, a fixed amount of the drug is released in the form of
a ‘puff’ containing drug-droplets of uniform size. The released drug is then inhaled deep into
the lungs by the user for its effects.
Remember
that
Inhalers are the preferred than tablets and injections
Inhalers are Safe
Inhalers are Non-addictive
Inhalers are Effective
Most inhalers contain similar drugs as in tablets, capsules,
syrups and injections of same name, with the added advantage of
-The dose of the drug is very small
-The drug is delivered to the site of the
problem – i.e. the lung.
How to Use
An Inhaler?
Remember that the
most important cause of failure of inhalational treatment is a wrong technique
employed for inhalation. A good
coordinated effort is required at each step of inhalation. There are some variations in the use of
metered dose aerosol and dry-powder inhalers available from different
manufacturers.
i.
Carefully read
the instructions on the pamphlet supplied with the drug.
ii.
Practice in front
of your doctor/asthma educator.
DO NOT HESITATE to ask questions.
iii.
Always rinse your
mouth and spit the water after an MDI or DPI is used. Some steroid inhalers can result in
hoarseness of voice and fungus growth in the mouth in a small percentage of
patients. Rinsing mouth prevents these
problems.
The exact steps of M.D.I. use are listed
below:
a.
Remove the mouth
piece cover
b.
Hold the MDI
between your thumb at the bottom and index finger on the top of the canister.
c.
Shake the inhaler
well.
d.
Breathe out
through your open mouth
e.
Place the
mouthpiece of the MDI between your teeth or 3 fingerbreadths away from mouth.
f.
Close your lips
and slightly tilt your head backwards.
g.
Start taking a
slow and long breath.
h.
When you start
inhalation, press the canister down (actuation) to release one dose but DO
NOT HOLD YOUR BREATH WHEN YOU RELEASE THE DRUG.
i.
Continue inhalation
to your maximum inspiration.
j.
Remove the
inhaler from your mouth.
k.
Hold your breath
for about 10 seconds or as long as you can.
l.
Breathe out
slowly. This completes one cycle.
If you need another dose, repeat all the steps
after a gap of one or two minutes.
There are three important steps in
the use of an inhaler:
i.
ACTUATION (of
inhaler) and RELEASE (of the drug from
the canister)
ii.
INHALATION
(inspiration) into the lungs
iii.
RETENTION of the
drug in the lungs
Actuation,
Release and Inhalation require a good understanding and a degree of
coordination by the patient to avoid wastage of the drug and ensure its proper
delivery into the lungs.
‘Retention’ of the drug requires
breath-holding for as long as possible (usually about 6-10 seconds), to allow
absorption (of the drugs) into the lungs.
How
to improve drug delivery to the Lungs?
Several methods are used to overcome the problem of coordination with
MDIs. The use of a ‘spacer’
between the inhaler and the mouth is one such device. The
use of a spacer makes the inhalation easier. The spacer is attached with a mouthpiece at
one end and an MDI at the other. The
drug from the MDI is released in the spacer and inhaled from the other end by
the patient. Many different kinds of
spacers are available in the market. The
newer ones are more compact than the older ones.
Dry Powder Inhalers (DPI): A DPI contains the drug in a finely
micronized powder form. There are several types of DPIs available in the
market. The greatest advantage of DPIs
is the ease of use – the drug is released only on inspiration. The steps of Actuation, Release and
Inhalation are therefore, much better coordinated and no wastage of drug
occurs. Inhalation from Dry Powder Inhalers
is also easier. There is no difficulty
in coordinating between the release of drug and the actual inhalation since the
drug is released only during an inspiratory effort.
While
new devices for inhalation are being developed on a regular basis, one can also
anticipate that the inhalation route in future will be used for administration
of a number of drugs other than the anti-asthma medicine.
