Transcript AEROSOL DELIVERY DEVICES

AEROSOL DELIVERY DEVICES
Ma. Henrietta O. de la Cruz, M.D.
Educational components of Asthma
Treatment Strategies
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Teaching and monitoring the inhalation technique of drugs
is important.
Short courses of oral corticosteroids are occasionally
needed.
All persons with asthma should avoid exposure to high
allergen concentrations (Gøtzsche et al., 2004) [B] and,
for example, sensitizing chemicals at work.
Aspirin and other nonsteroidal anti-inflammatory drugs
(NSAIDs) should be used cautiously, as 10 to 20% of
patients with asthma are allergic to these drugs.
Smoking may wreck the results of asthma care.
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Develop an ACTION PLAN for self management
The treatment should be tailored for each patient
according to the severity of the disease and modified
flexibly step-by-step. Self-management of drug dosing is
encouraged (written instructions!).
Allergen immunotherapy may help some patients
(Abramson, Puy, & Weiner, 2003; Malling, 1998) [A].
Why inhalation therapy?
Oral
Slow onset of action
Inhaled route
Rapid onset of action
Large dosage used
Less amount of drug
used
Greater side effects
Not useful in acute
symptoms
Better tolerated
Treatment of choice
in acute symptoms
Particle deposition
Uses of Aerosols
THERAPEUTIC
 COPD and Asthma
 Beta2-Adrenergic agonists
 anticholinergic drugs
 Diagnostic use
 bronchial aerosol
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 steroids
 cromolyn sodium
 Alveolar diseases
 emphysema (recombinant alpha1-
antitrypsin)
 interstitial lung diseases (steroids,
questionable reports)
 Abnormalities of the Mucociliary
Transport System
 reduce tenacious mucus
 widely applied in clinical practice
but may have little scientific basis
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challenge
measurement of
dimensions of airways and
alveoli
ventilation scintigraphy
mucociliary clearance
alveolar particulate
clearance
Therapeutic Uses of Aerosols
 Immunization and Lung infections
 pseudomonas infection in cystic fibrosis
 pneumocystis infection in HIV infection
 Systemic drug delivery
 inhaled analgesia with fentanyl or morphine
 nasal sprays for calcitonin, oxytocin
Aerosol delivery equipment
 small volume nebulizers
 large volume nebulizers
 metered dose inhalers
 dry powder inhaler
 continuous therapy nebulizers
 auxiliary spacing devices
*other specialized aerosol delivery equipment to
reduce mass median aerodynamic diameter of 25 um
MDI: metered dose inhaler
Using your MDI correctly:
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 Remove the cap from the
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mouthpiece and shake the MDI well.
Exhale slowly though pursed lip.
Hold the inhaler upright and place it
in front of your mouth. Keep your
mouth slightly open.
Breathe in deeply (and at the same
time) press the inhaler between your
thumb and forefinger. This forces
the medication from the inhaler in a
“puff” that you then inhale into your
lungs.
Remove the inhaler from your
mouth, holding your breath counting
to 10. Then exhale slowly through
pursed lips.
Most inhaler instructions ask you to
take two puffs. You need to wait
about two minutes before taking the
second puff, using the same
technique as described in steps 1,
2, 3 and 4 above.
Laryngeal deposit with MDI
 45-95% of the drug
impacts in the
oropharyngeal region
 only 5-25% reaches the
lower airways
 regional deposition
depends on:
 specific drug and MDI
 inertia due to mass cause
particles to continue their
present trajectory rather than
follow curvature of airways
 impaction is proportional to:
 inhalation pattern and
 velocity
airway geometry
 hand-breath coordination
 diameter of particle
 deposition improves
dramatically if a holding
chamber is used
 sharpness of airway turns
 inverse of airway radius
 impaction is dominant in the
major and segmental bronchi
for rapidly inhaled particles
greater than 4 um
MDI vs Nebulizer
 4-12 puffs by MDI with
spacer achieves same
degree of
bronchodilation
as one 2.5 mg
nebulized
treatment of albuterol
 MDI with spacer are
cheaper & faster
delivery
Spacers and Holding Chambers
 reduction of drug deposition in the
oropharynx to 3-35% (from 45-95%)
 minimizes local side effects of
steroids
 amount of systemic drug uptake via
the stomach and intestine is reduced
by 40-80%
 demands of coordination when using
a spacer are minimal
 asthmatic infant
 elderly
Dry Powder Devices
Powder Devices
 Dry powder inhalers (DPI’s) are
breath activated, multidose or
single dose, portable devices
containing a drug
 in general, they deliver a greater
amount of drug as small
respirable particles (<5-6um) if
inhalation flow rate is high
 only few patients above 6y.o. are
unable to create large enough
flow rates
Aerosol Generation and Delivery: Powder
Devices
 the usual deposition pattern is
50-70% in the oropharynx and
10-35% in the lungs (not very
different from pMDI’s)
 deposition rates vary according
to the types of DPI
 turbuhaler is among the most
efficient, having a lung
deposition of 25-35%
HOW TO USE TURBOHALERS
 Unscrew and lift off the cover.
 Hold the inhaler upright with the grip
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downwards.To load the inhaler with a dose,
turn the grip as far as it will go in both
directions, listening for a click. Do not hold
the mouthpiece when you load the inhaler.
Breathe out. Do not breathe out through the
mouthpiece.
Place the mouthpiece gently between your
teeth, close your lips and inhale forcefully
and deeply through your mouth.
Remove the inhaler from your mouth before
breathing out.
If more than one dose has been prescribed,
repeat steps 2-5. Replace the cover.
Rinse your mouth out with water. Do not
swallow.
Mechanisms: Sedimentation
 depends on the terminal
velocity of a particle under
the influence of gravity
 terminal velocity is
proportional to:
 density of particle
 diameter of particle
 enhanced by breath-
holding or slow steady
breathing
Comparison between MDI & DPI
High velocity aerosols
Requires hand breath coordination
Delivery of medicines
independent of external
factors
Time consuming to teach
Requires deep& slow
breathing only
Aerosol velocity depends
on inspiratory flow rate
No hand breath coordination needed
Delivery of medication
largely dependent on
external factors
Easy to teach
Requires high inspiratory
flow>28L/min
Deposition%
Loss in air
Apparatus
GI
Lung
MDI
DPI
Nebulizer
SMALL VOLUME NEBULIZERS
PORTABLE MODEL SVN
Aerosol Generation and Delivery:
Nebulizers
 solutions or suspensions of drugs can
be aerosolized via nebulizers
 nebulizers are driven ultrasonically or
by compressed air
 most of the drug is retained in the
nebulizer, and only about 2-10%
reaches the lower airways
 Nebulizers require few
instructions, less
supervision & coordination
& maybe preferred by the
Patient
 new brands work only during
inspiration, so loss from aerosolization
during expiration is reduced
Mechanisms of Aerosol Deposition
 Inertial impaction
 Sedimentation
 Diffusion
 Electrostatic precipitation
 Interception
Mechanisms: Diffusion
 important mechanism for
deposition of particles <0.5um in
diameter
 extremely small particles are
displaced by the random
bombardment of gas molecules
and collide with the airway walls
 does not account for much of the
deposition of therapeutic
aerosols
Choice of inhalation therapy
 Infants
Nebulizer
 Children
< 4 years
4 year
7 years
 Adults
 Acute episodes
Nebulizer
DPI/MDI/Spacer
DPI/MDI
MDI/DPI
Nebulizer
Hazards of therapy
 Bronchospasm
 Over hydration
 Overheating of inspired gases
 Delivery of contaminated aerosol
 Tubing condensation draining into the airway
 Malfunction of device and/or improper technique may
result in underdosing.
 improper technique (inappropriate patient use)
overdosing.
 Complications of specific pharmacologic agent may
occur.
 CFC: affect the environment by its effect on the ozone
layer
INFECTION CONTROL:
 Universal Precautions for body substance isolation.
 SVN and LVN are for single patient use or should be
subjected to high-level disinfection between patients.
 Published data establishing a safe use-period for SVN
and LVN are lacking; however they probably should be
changed or subjected to high-level disinfection at
approximately 24-hour intervals.
MEDICATIONS:
 Medications should be handled aseptically.
 Tap water should not be used as the diluent.
 Medications from multidose sources in acute care
facilities must be handled aseptically and discarded after
24 hours.
 MDI accessory devices are for single patient use only.
Cleaning of accessory devices is based on aesthetic
criteria.
 There are no documented concerns with contamination
of medication in MDI canisters.
Patient Education in the Clinic
 Explain nature of the disease (i.e.
inflammation)
 Explain action of prescribed drugs
 Stress need for regular, long-term therapy
 Allay fears and concerns
 Peak flow reading
 Treatment diary / booklet
Patient Education
 Consider issuing a peak
flow meter & giving
appropriate education on
peak flow monitoring
 Review or develop a
written plan for managing
relapses
 Review the patient’s
understanding of the
causes of exacerbations,
correct uses of medication
& actions to be taken for
worsening symptoms or
peak flow measurement
Self Management Plan
 Keep it simple
 If your PEFR falls
below 50-80% of your
personal best start
taking your oral
steroids.
 Or if you start waking
at night with
symptoms or develop
a cough on exertion.
Assessment of efficacy
 Proper technique applying device
 Patient response to or compliance with procedure
 Objectively measured improvement (eg,
increased FEV1 or peak flow)
Demonstration