INHALATION THERAPY IN ASTHMA AND COPD

Posted by e-Medical PPT Sunday, November 11, 2012
Types
Pressurized  metered dose inhaler (pMDI)
MDI with spacers or holding chambers
Breath actuated MDI
Dry powder inhaler (DPI)
Nebulizers

Propellants
Provides the force to generate the aerosol cloud and is also the medium in which the active component must be suspended or dissolved. Propellants in MDIs typically make up more than 99% of the delivered dose

Chlorofluorocarbons (CFCs)
    most commonly used propellants were the chlorofluorocarbons CFC-11, CFC-12 and CFC-114.
    Banned due to adverse effect on ozone layer

hydrofluoroalkanes (HFA)
    HFA 134a (1,1,1,2,-tetrafluoroethane)
    These new devices are more effective. The HFA propellant produces an aerosol with smaller particle size, resulting in improved deposition in the small airways and greater efficacy at equivalent doses compared with CFC MDIs.
When the valve is actuated propellant and drug leave the inhaler at high velocity
Majority of drug impacts in oropharynx
Less than  25% reaches the lung

Most efficient way of using MDI- steps
Shake the canister
Place the mouthpiece of actuator between the lips
Breathe out steadily
Release the  dose while taking  a slow  deep breath in
Hold the breath in while counting to 10

Advantages of MDIs
Compact, portable ,convenient
Multidose delivery capability
Lower risk of bacterial contamination
Suitable for emergency situation

Disadvantages of MDIs
Needs correct actuation and inhalation coordination- difficult for children and elderly patients
Cold freon effect
High pharyngeal drug deposition
Flammability possibility of new HFA propellants
Remaining dose –difficult to determine

Steps for Using a Spacer with an MDI
Insert the inhaler/canister into spacer and shake.
Breathe out.
Put the spacer mouthpiece into your mouth.
Press down on the inhaler once.
Breathe in slowly (for 3-5 seconds).
Hold breath for 10 seconds.

Advantages of MDI with spacer
Compensate for poor technique/coordination with MDI
Spacers slow down the speed of the aerosol coming from the inhaler, meaning that less of drug impacts on the back of the mouth and somewhat more may get into the lungs. Because of this, less medication is needed for an effective dose to reach the lungs, and there are fewer side effects from corticosteroid residue in the mouth.
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