Pulmonary Drug Delivery II Flashcards
What addition to the inhaler is there for children?
A valved holding chamber (spacers) +/- facemask is often used
What is special about the valve in the spacer?
‘one-way’ valve, only allowing pressure towards the mouth and NOT back in
pMDIs and special patient groups
Spacers do not require the patient to coordinate their breathing with the actuation of the pMDI
________ the initial droplet velocity and allows time for propellant to evaporate
reduces
What issues might patients face using inhalers?
Patients with limited dexterity, e.g. arthritis
Partially-sighted patients or with reduced vision
Patients with cognitive impairment
Elderly – lung function reduces over time (a problem for DPI use)
What may patient facing issues with inhalers benefit from?
spacer or potentially breath-actuated pMDIs or nebulizer therapy
Examples of Breath-actuated pMDIs?
Easyhaler, Autohaler, Easi-Breathe, assist with coordination of inspiration and actuation
What does INSPIRATION by the patient trigger?
the release of the drug, i.e. opening of the metering chamber
Dry powder inhalers (DPIs)
use no propellant and rely on the force of the patient’s inspiration to carry the drug (as a dry powder) into the lungs
List the two common categories of DPIs?
- Drug in hard capsule DPIs
- Multidose DPIs (multiple unit dose OR reservoir type)
What are the advantages of DPis?
- Propellant free, i.e. better for the environment than pMDIs
- Being breath-actuated they avoid inspiration and actuation coordination issues
- Can deliver larger doses of drug than pMDIs
What are the disadvantages of DPIs?
- DPIs require inspiratory flow rates of 30-90 L/minute
- Sometimes a higher upfront cost
- DPIs more exposed to ambient air which may cause stability issues
Drug particles should be <___ um for biopharmaceutical reasons»_space;> need to be micronized
5um
Micronization:
process of reducing drug particle size to micron size ranges (typically <5 m in diameter)
Micronized particles often have _____ flow properties due to static / cohesive / adhesive nature
poor
Drug (micronized) particles mixed with much larger (30 um to 150 um) carrier particles to ______ flow
improve
smaller the particles the ______ the flowability, why?
worse
the particles form electrostatic interaction between each other which effects on the flow
Process of DPi
1) patient breathes in
2) pressure into the turban
3) larger particles will stay in the mouth
4) smaller particles will go down the airways and into the lungs
DPI capsule, what is the shell made out of?
hard-shelled gelatin capsule
STEP BY STPE OF USING A DPI CAPSULE (1)
1) Capsule is loaded into the device by the patient
2) Punctured by two metal needles inside the device
3) Inspiration by the patient causes a rotor to rotate andthis causes a turbovibratory air pattern to disrupt thepowder in the capsule
MULTIDOSE DPIs (2), what are the 2 categories?
Multiple unit dose device
Reservoir-based device
What are Smart inhalers?
Smart inhalers use sensors in thedevice to detect and record on the use of the inhaler
How do smart inhalers work?
inhaler connects via Bluetooth to a smartphone or other device and (should the patient choose to) their data can be shared with the prescriber/ asthma specialist
What data does the smart inhaler gather?
How often the device is use
Inspiratory flow rate (important for a DPI)
What are Nebulizers?
much larger pulmonary delivery devices that generate aerosols from the contents of unit dose nebules
NOT PORTABLE - size and power requirements
how are nebulisers used?
inhaled during NORMAL breathing usually via a mask
used in hospital and domiciliary settings
What is the formulation of Nebules?
drug dissolved in “normal saline”
Normal saline is a ____% w/v NaCl aqueous solution
0.9%
Venolin Nebules
= solution
What excipients?
- NaCl
- Sulphuric acid if required to adjust pH
- Purified water
Flixotide = suspension
a number of surfactants need to be used to keep it homogenous and stable
Jet Nebulizers, what do they require?
compressed air from a cylinder, hospital air line or electrical compressor
Jet Nebulizers, what is the drug delivery determined by?
Aerosol droplet size and drug delivery is determined by the compressed gas flow rate
Jet nebulizer: Compressed air passed through the _______ nozzle – low pressure created draws liquid up from the reservoir through a feed tube
Venturi
Jet nebulizer, what is the role of the ‘Baffle’?
ensures that (larger) non-respirable particles are not inhaled and can be recycled
Ultrasonic Nebulizers’s role:
Energy to generate aerosol comes from a vibrating piezoelectric crystal
Ultrasonic Nebulizers’s
Diagram (on pp) LABEL
Piezoelectric transducer = chemical energy to mechanical energy > sound waves
reaches the diaphragm and reaches the aerosol chamber where gas is fed in and aerosol goes out
Mesh Nebulizers
may have up to 7000 holes etched with a laser
How do mesh nebulizers work?
Vibrational energy due to a piezoelectric crystal which transfers energy to the mesh via a transducer
(Newer designs are able to coincide aerosol release with the patient’s breathing > reducing drug wastage)
