pMDIs and DPIs Flashcards
Pressurized metered dose inhaler
Delivers drugs for multiple dosing using metering valves with the help of PROPELLANTS
Major components of pMDI
Container
Metering valve (25-100 microL)
Spray actuator
Formulation for pMDI
Drug
Propellants
Surfactants and lubes
Surfactants are used for?
To disperse drug particles in suspension or lube the valve
What does the acutator do?
Provides an orifice for discharge of spray to patient’s mouth
How doe pMDIs work?
Aersolization begins with propellants leave the actuator as a plume due to vaporization
Particle size decreases rapidly due to evaporation as the cloud moves away from the nozzel
Breath actuated MDIs?
Reduce or eliminate the hand-breath coordination
Senses the patient inhalation through the actuator and fire the inhaler automatically
- Autohaler
Autohaler
Patient life to prime the device before inhalation
Patients press and breathe at the same time
Propellant free MDIs
Produce aerosols without propellants
- Respimat
Respimat?
Transform aqueous solution to liquid aerosol droplets
Propellant free multi-dose hand held inhaler
Correct use of pMDIs?
Shake before inhalation
Prime several times to make sure there aren’t erratic first sprays
Spacer devices?
Reduce oropharyngela deposition and increase lung deposition
Increase distance between point of spray and mouth
Faster particles will strike the container
Reduce or eliminate the coordination between actuation and inhalation
Medical benefit of spacer devices?
Reduces the risk of oral candiasis and dysphonia with inhaled corticosteroids
Reduce potential systemic absorption from GIT
Disadvantages of spacer devices?
Cumbersome
Reduce dose bc of electrostatic charge
- Charge removed by priming chamber or washing with ionic detergent
Types of spacers?
Simple tube extension
Valved holding chamber
Reverse flow device
Valved holding chamber
One way valve for the aerosol to remain within the device until patients inhales
- Helps prevent blowing away the dose
Reverse flow devices
Use a bag which collapses upon inhalation
Use a chamber with air vent that opens during inhalation
Dry powder inhalers
Contain solid drug suspended in a dry powder mix that can be fluidized when patients inhales
- Micronized drug particles with larger carrier particles
- Powders are solid when static, liquid when they flow
Carriers?
Prevent aggregation and improve flow
Dry powder inhaler particle movement?
Passive or active
Passive
Patients activate and inhale
- Breath actuated
Inhalation: airflow creates shear and turbulence and air is introduced in the powder bed -> fluid and enters patient
- Deep in the lungs but deposition depends on patient’s inspiratory airflow
Active
Power assisted
- Pneumatic, impact force and vibratory
- Drugs with narrow therapeutic windows
- Spiros and Microdose
Excipients in DPIs?
Lactose
Mannitol and Glucose
OR none (plumicort and turbuhaler)
Lactose
improves handling, dispensing and metering of the drug by reducing cohesive forces between drug particles
Large porous particles for DPIs
Aerodynamic diameter is smaller than their volume diameter
Made in the respiratory aerdynamic diameter range (even if they are 20 micrometers)
PulmoSpheres (Large porous particles)
Low density particles
Lesser susceptibility to phagocytosis
Lesser aggregation
- Tobi-Podhaler
Unit dose with drug in hard gelatin capsules
Placed individually in device
- Handihaler
Multidose with drug in foil blister
Loaded by patient
- Diskhaler
Multi-dose with drug preloaded in the devide
Preloaded and sealed
- Diskus
Reservoir type of device
A dose is measured and delivered from a drug reservoir
- Metering cups are filled by gravity from reservoir and delivered to an inhalation passage
- Clickhaler
Diskhaler
Multidose
Reloadable
- Pierce the foil to release the dose
Diskus
Dosage pack sealed during manufacturing
Wheels guide the foil strips and aligns each newly opened blister with air passageways
Nebulizers Advantages
No specific inhalation technique or coordination required
Aerozolizes most drug solutions
Deliver large doses
Good for infants or sick patients
Nebulizers Disadvantages
Time consuming Bulky Non-portable Easy contaminated Poor delivery efficiency Drug wastage Huge variation
pMDIs Advantages
Compact Portable Multi-dose Inexpensive Sealed environment Reproducible dosing
pMDIs Disadvantages
Partient coordination
High oral deposition
5 mg max dose
Limited range of drug available
DPIs Advantages
Compact Portable Breath actuated Easy to use No coordination
DPIs Disadvantages
Respirable dose dependent on inspiration
Humidity: aggregation
Lose the dose if exhale into the device
Contains lactose
Inhaled Insulin Exubera
Rapid acting insulin
Blister packages
No longer used
