AEROSOL DELIVERY DEVICES

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