Aerosol Drug Delivery Concepts

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Questions and Answers

What is the primary mechanism for deposition of particles smaller than 3 μm in the respiratory system?

Sedimentation

Diffusion

Brownian diffusion (correct)

Gravitational settling

Which range of particle sizes is primarily affected by sedimentation in the central airways?

Particles between 1 and 5 μm (correct)

Particles larger than 10 μm

Particles smaller than 1 μm

Particles between 5 and 10 μm

How can a 10-second breath hold affect aerosol deposition in the lungs?

It has no effect on deposition

It decreases deposition by 10%

It increases deposition by 10% (correct)

It increases deposition by 20%

What term describes the process by which an aerosol suspension changes over time?

Aging Signup and view all the answers

What is considered a primary hazard of aerosol drug therapy?

Adverse reaction to medication Signup and view all the answers

Which of the following can lead to nosocomial infections during aerosol therapy?

Contaminated solutions or equipment Signup and view all the answers

Which medication is known to be associated with increased airway resistance during aerosol administration?

Acetylcysteine Signup and view all the answers

How does a particle's size affect its depth of penetration into the respiratory tract?

Smaller particles penetrate deeper than larger particles Signup and view all the answers

What is aerosol output defined as?

The mass of fluid or drug contained in aerosol produced by a nebulizer Signup and view all the answers

Which method is used to measure aerosol particle size?

Mass median aerodynamic diameter (MMAD) Signup and view all the answers

What primarily influences the site of deposition of aerosol particles in the respiratory tract?

The particle size of the aerosol Signup and view all the answers

Which mechanism is NOT a key cause of aerosol deposition?

Condensation Signup and view all the answers

Larger aerosol particles (>5 um) primarily deposit due to which mechanism?

Inertial impaction Signup and view all the answers

What effect does laminar flow have on medication delivery to the airways?

Allows medication to go deeper into the airways Signup and view all the answers

Which of the following best describes the process of inertial impaction?

Particles in motion collide with a surface Signup and view all the answers

What does MMAD indicate about aerosol particles?

The diameter at which 50% of the particles by mass are larger and 50% are smaller Signup and view all the answers

What is the primary advantage of dry powder inhalers (DPIs) compared to metered dose inhalers (MDIs)?

DPIs do not require coordination between hand and breath. Signup and view all the answers

Which group of patients is least likely to effectively use a DPI?

Infants and small children. Signup and view all the answers

What can cause a reduction in drug availability from a DPI?

Exhaling into the device. Signup and view all the answers

What is the effect of sedimentation on aerosol therapy?

Causes particles to settle out of suspension. Signup and view all the answers

In terms of the mechanism of aerosol deposition, which particle size range is primarily affected by sedimentation?

1 to 5 micrometers. Signup and view all the answers

Which of the following is a major hazard of aerosol drug therapy?

Adverse reaction to the medication. Signup and view all the answers

What is the primary component of the spray output from metered-dose inhalers (MDIs) by weight?

Propellant Signup and view all the answers

What effect does a 10-second breath hold have during aerosol therapy?

Increases overall drug delivery to the lungs. Signup and view all the answers

Which problem commonly hinders successful administration of aerosol drugs via MDIs?

Hand-breath coordination Signup and view all the answers

What is a common characteristic of hygroscopic powders in DPIs?

They tend to clump in high humidity, affecting particle size. Signup and view all the answers

How do spacers and holding chambers benefit MDI use?

Reduce the need for hand-breath coordination Signup and view all the answers

What is a significant issue some patients face when using MDIs?

Cold Freon effect Signup and view all the answers

What is a characteristic of newer multidose dry powder inhalers (DPIs) like the Turbohaler?

They are breath-actuated metered-dosing systems. Signup and view all the answers

Which of the following is true regarding the Autohaler in the United States?

It reduces pharyngeal impaction. Signup and view all the answers

What percentage of patients and health professionals incorrectly use MDIs?

Two thirds Signup and view all the answers

What limitation do flow-triggered MDIs address?

Hand-breath coordination problems Signup and view all the answers

What is the primary benefit of administering bronchodilators prior to other agents?

It reduces the risk of increased airway resistance. Signup and view all the answers

What phenomenon describes the increase in solute concentration during nebulization?

Reconcentration. Signup and view all the answers

Which of the following is NOT a name for a small-volume nebulizer?

Inhalator. Signup and view all the answers

What mechanism is primarily responsible for drawing liquid into the gas stream in small-volume jet nebulizers?

Bernoulli effect. Signup and view all the answers

What is the typical running flow rate of a small-volume nebulizer?

7 to 8 L/M. Signup and view all the answers

Which of the following components is NOT included in the therapy mnemonic 'O-G-P-A-E-R & WASH'?

Restock equipment after use. Signup and view all the answers

What primary type of medications is commonly administered using metered-dose inhalers (MDIs)?

Anticholinergics. Signup and view all the answers

What happens to small-volume nebulizers when tilted away from the vertical position?

They stop producing aerosol. Signup and view all the answers

Study Notes

Aerosol Drug Delivery: Key Concepts

An aerosol is a suspension of solid or liquid particles in a gas.
Aerosol output is the mass of fluid or drug in aerosol produced by a nebulizer. It's a key parameter in aerosol administration.
Particle size is crucial and depends on the nebulized substance, nebulizer type, and aerosol generation method.
Mass median aerodynamic diameter (MMAD) measures particle size; 50% of particles by mass are larger, 50% smaller. It describes particle sizes where deposition relies on inertial impaction and sedimentation.
Deposition site in the respiratory tract varies with particle size. Nebulizers producing specific size ranges improve targeting.

Aerosol Deposition Mechanisms

Inertial impaction: Particles collide with surfaces; primary deposition for large particles (>5 µm). Larger mass leads to greater inertia and deeper penetration. Fast, uneven airflow hinders deep penetration; laminar flow is better.
Sedimentation: Particles settle due to gravity; primary mechanism for 1–5 µm particles, mostly in central airways. A 10-second breath hold improves deposition by 10%, increasing lung parenchyma deposition fourfold.
Brownian diffusion: Primary mechanism for <3 µm particles in alveoli where gas flow ceases and particle inertia is low. Particles are easily moved by gas molecule collisions.

Aerosol Aging and Hazards

Aerosol aging describes how suspensions change over time (particles grow, shrink, or fall out).
Primary aerosol therapy hazard: adverse drug reactions. Other hazards: infection, airway reactivity, systemic effects of bland aerosols, and drug reconcentration.
Infections can arise from contaminated solutions, caregivers' hands, or patient secretions.
Some medications (e.g., acetylcysteine, antibiotics, steroids) may increase airway resistance and bronchospasm; pre-treatment with bronchodilators may help.
Drug reconcentration can occur during nebulization, especially with long durations, exposing patients to higher concentrations.

Nebulizers: Small-Volume Jet Nebulizers (SVNs)

Also known as acorn nebs, SVN, med neb, mini neb, BAN (breath actuation nebulizer).
Powered by air or oxygen, sometimes by Pulmo-Aide nebulizers.
Powered by a high-pressure gas stream through a restricted orifice (Bernoulli effect) drawing liquid into the stream which is then sheared into droplets by a baffle.
Residual volume depends on SVN position; some stop producing aerosol when tilted.
Most run continuously until dry; some allow intermittent nebulization (used with ventilators). Typical running flow is 7–8 L/min.

Metered-Dose Inhalers (MDIs)

Most common aerosol delivery method in the US. Used for bronchodilators, anticholinergics, and steroids.
Output volume varies; 60–80% is propellant, only about 1% is active drug.
Technique is critical; many patients and healthcare professionals use them incorrectly.
Hand-breath coordination problems (actuating before/after breath) are common. Some patients struggle with MDI use (infants, children, elderly, those in acute distress). The cold freon effect may also reduce effectiveness.

MDI Accessory Devices

Address hand-breath coordination and oropharyngeal deposition.
Include flow-triggered MDIs, spacers, and holding chambers. These reduce oropharyngeal deposition, improve coordination, reduce bad taste, and eliminate the cold Freon effect.
Autohaler (only available with pirbuterol) reduces pharyngeal impaction and enhances lung deposition.

Dry Powder Inhalers (DPIs)

Breath-actuated, metered-dosing systems; the patient creates the aerosol by inhaling.
Relatively inexpensive, propellant-free, and less technique-dependent than MDIs.
Lung deposition and drug response are comparable to MDIs; some patients prefer them.
Not suitable for infants, young children (<5 years), those unable to follow instructions, or those with severe airway obstruction (e.g., COPD). Should not be used for acute bronchospasm.
While hand-breath coordination is less critical, exhaling into the device causes drug loss, and high humidity can affect drug availability due to hygroscopic powder clumping.

Therapy Mnemonic

Orders, Gather equipment, Prepare equipment and patient, Assess patient, Evaluate therapy, Record and report, Wash hands.

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Description

This quiz explores the fundamental concepts of aerosol drug delivery, focusing on aerosol output, particle size, and the importance of mass median aerodynamic diameter (MMAD). Understand how deposition mechanisms like inertial impaction and sedimentation affect aerosol effectiveness and targeting within the respiratory tract.