ma. henrietta o. de la cruz, m.d. aerosol delivery devices
TRANSCRIPT
Ma. Henrietta O. de la Cruz, M.D.
AEROSOL DELIVERY DEVICES
Educational components of Asthma Treatment Strategies 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.
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
Large dosage used
Greater side effects
Not useful in acute
symptoms
Inhaled routeRapid onset of
action
Less amount of drug used
Better tolerated
Treatment of choice
in acute symptoms
Particle deposition
Uses of AerosolsTHERAPEUTIC COPD and Asthma
Beta2-Adrenergic agonists anticholinergic drugs 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
Diagnostic usebronchial aerosol
challengemeasurement of
dimensions of airways and alveoli
ventilation scintigraphymucociliary clearancealveolar particulate
clearance
Therapeutic Uses of AerosolsImmunization and Lung infections
pseudomonas infection in cystic fibrosispneumocystis infection in HIV infection
Systemic drug deliveryinhaled analgesia with fentanyl or morphinenasal sprays for calcitonin, oxytocin
Aerosol delivery equipmentsmall volume nebulizerslarge volume nebulizers metered dose inhalers dry powder inhalercontinuous therapy nebulizers auxiliary spacing devices
*other specialized aerosol delivery equipment to reduce mass median aerodynamic diameter of 2-5 um
MDI: metered dose inhaler
Using your MDI correctly: Remove the cap from the
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 Laryngeal deposit with MDIMDI
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 inhalation pattern and
airway geometry hand-breath coordination
deposition improves dramatically if a holding chamber is used
inertia due to mass cause particles to continue their present trajectory rather than follow curvature of airways
impaction is proportional to: velocity diameter of particle 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 Nebulizer4-12 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
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: Sedimentationdepends on the terminal
velocity of a particle under the influence of gravity
terminal velocity is proportional to:density of particlediameter of particle
enhanced by breath-holding or slow steady breathing
Comparison between MDI & DPIHigh velocity aerosolsRequires hand breath co- ordinationDelivery of medicines independent of external factorsTime consuming to teachRequires deep& slow breathing only
Aerosol velocity depends on inspiratory flow rateNo hand breath co- ordination neededDelivery of medication largely dependent on external factorsEasy to teachRequires high inspiratory flow>28L/min
MDI DPIMDI DPI NebulizerNebulizer
Deposi
tion%
Deposi
tion%
Lung Lung
GI GI
ApparatusApparatus
Loss in airLoss in air
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 fewinstructions, lesssupervision & coordination& maybe preferred by thePatient
new brands work only during inspiration, so loss from aerosolization during expiration is reduced
Mechanisms of Aerosol DepositionInertial impactionSedimentationDiffusionElectrostatic precipitationInterception
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 therapyInfants NebulizerChildren
< 4 years Nebulizer
4 year DPI/MDI/Spacer
7 years DPI/MDIAdults MDI/DPIAcute episodes Nebulizer
Hazards of therapyBronchospasmOver hydrationOverheating of inspired gasesDelivery of contaminated aerosolTubing condensation draining into the airwayMalfunction 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 ClinicExplain 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 EducationConsider issuing a peak flow meter & givingappropriate education onpeak flow monitoring Review or develop awritten plan for managing
relapsesReview the patient’s
understanding of thecauses of exacerbations,
correct uses of medication & actions to be taken for
worsening symptoms or peak flow measurement
Self Management PlanKeep it simpleIf 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 efficacyProper technique applying device Patient response to or compliance with procedure Objectively measured improvement (eg,
increased FEV1 or peak flow)
Demonstration