DPIs

?
  • Created by: LBCW0502
  • Created on: 02-03-19 13:18
What are the advantages of DPIs?
No CFCs, breath actuated (no coordination problems), high doses can be delivered
1 of 30
What are the disadvantages of DPIs?
Complex systems. Can patient's breath disperse the powder?
2 of 30
What is the general principle for DPIs? (1)
Particle size of 1-5 microns. Need to have carrier (to improve flowability of drug). Drug particles and carrier in ordered mix. Metering (capsule, blisters, blister disk, powder reservoir). Passive or active dispersion, deposition
3 of 30
What is the general principle for DPIs? (2)
Drug particles detach from carrier (not all particle detach, may deposit in mouth/throat). Passive (pass through) or active (mechanism) e.g. insulin inhaler (change from active to passive)
4 of 30
What is a single unit dose?
Twist device, capsule opens, dose ready to be released (can be disposable or reusable)
5 of 30
What is the multi-unit dose factory metered?
Set doses inside device (pre-filled doses). Rotation/twisting/pressing button leads to dose being set/ready for release
6 of 30
What is the multi-unit reservoir/patient metered dose?
Reservoir of drug powder. Twisting device, scoop out amount of drug required (dose) - ready for release
7 of 30
Give examples of a single dose factory metered device
Spinhaler, rotahaler, inhalator, cyclohaler, flowcaps
8 of 30
Give examples of a multi dose factory metered device
Diskhaler, diskus, accuhaler
9 of 30
Give examples of a multi dose patient metered device
Turbuhaler, pulvinal, easyhaler, clickhaler, ultrahaler
10 of 30
Outline features of device and formulation strategies to address patient needs (1)
Lactose used as excipient. Passive DPI (cause turbulence but twisting device, particles with carriers). Active DPI (need mechanism, carrier free particles - can be active or passive).
11 of 30
Outline features of device and formulation strategies to address patient needs (2)
Reasonable filling capabilities. Good flowability. High dispersibility. Uniform dose. High % of deposition. Ease of use. Patient compliance
12 of 30
Which factors affect drug delivery from DPIs? (1)
Design of inhaler devices (dispersion mechanism, active/passive, device resistance, aerosolisation efficiency). Powder formulation (drug-drug cohesiveness, drug carrier adhesiveness, particle size, shape, surface texture, crystallinity)
13 of 30
Which factors affect drug delivery from DPIs? (2)
(hygroscopicity, density). Inhalation manoeuvre (flow rate, tidal volume, breath holding, breathing frequency, air acceleration). Physiology of respiratory tract (geometry, lung function, pulmonary ventilation, mucus secretion)
14 of 30
Outline features of designing passive inhaler devices
Simple to use. Compact. Inexpensive. High aerosolisation efficiency with low inspiratory effort. Reproducible emitted/fine particle doses. Preferably multi dose. Maintain physicochemical stability of drug formulation over prescribed shelf-life
15 of 30
What is PIFR? (1)
Peak inspiratory flow rate - maximum air flow (L/min) produced by inhalation of patient. Average for asthmatic patient - 150 L/min. Dependent on device resistance. Effort required to achieve efficient actuation dependent on device design
16 of 30
What is PIFR? (2)
Similar inspiratory effects may produce different flow rates in different inhalers (turbulent flow). Similar inspiratory effectors may produce different drug dispersion and deaggregation patterns in different inhalers. PIFR varies in DPIs
17 of 30
How does PIFR vary with DPIs? (1)
E.g. rotahaler has a higher PIFR compared to turbohaler (high PIFR means less resistance). A high device resistance doesn't mean low efficiency. High resistance devices usually show better powder dispersion/aerosolisation properties
18 of 30
How does PIFR vary with DPIs? (2)
At low airflow rates - depending upon device design and delivered drug
19 of 30
Outline features of the direct haler (powder whirl technology)
Delivery drug through straw. Tubular ridges cause drug to spin around and cause dispersion. Inhalation either through nose or mouth. Cheap/disposable device. Issues - drug stability/storage
20 of 30
Describe features of designing an active inhaler
Simple to use, compact, inexpensive, high aerosolisation efficiency independent of patient inspiratory effort, reproducible emitted/fine particle doses. Preferably multi-dose. Maintain physicochemical stability of drug over prescribed shelf-life
21 of 30
What are the powder dispersion mechanisms?
Compressed air (Nektar Pulmonary Inhaler, Vectura Aspirair system). Hammer impaction (development). Piezo-vibrating membrane (Oriel Therapeutics, Microdose DPI)
22 of 30
Outline features of the ALEXZA inhaler
No excipients used. Substrate heated and coated with drug (sublimation properties of drug). Reaches 200 degrees Celsius. Operating. Cools down, droplets of drug to be inhaled. Designed for systemic delivery. Ensure no degradation at high temperatures
23 of 30
Describe the basic principle of formulations using carrier particles
Most drug particles are removed from carrier but there are some interactions (some drug stays on lactose). Micronised drug, ordered mix. Lactose carrier deposited in mouth/throat. Small particles follow airstream into respiratory tract
24 of 30
How do we make DPIs perform better? (1)
Make carrier smaller/rounder (less gaps where drug can get stuck but more gaps for drug to be for ordered mix). Make carrier smoother (less ridges where drug can be trapped)
25 of 30
How do we make DPIs perform better? (2)
Add force control agents (cover all small ridges/gaps where drug could be trapped)
26 of 30
What happens when you combine two drugs?
Drugs will have different binding properties. Difficult to ensure correct proportions of the drugs and to regulate the different doses of the different drugs
27 of 30
What happens if the drug particles are <1 micron?
Issue - nanoparticles (too small, can be removed easily). Hypothesis - nano-sized drug powders, when blended with lactose, show an enhanced lung deposition profile compared to micronised drug powders (drug has greater properties)
28 of 30
Give an example of a formulation without carriers
Use of fungal pores with porous structures (aerodynamic diameter - decreasing density can lead to having larger particle size and faster movement of particle)
29 of 30
How do we advice patients to use their DPI?
Fast inhalation (need to have enough turbulence in device to allow particle dispersion)
30 of 30

Other cards in this set

Card 2

Front

What are the disadvantages of DPIs?

Back

Complex systems. Can patient's breath disperse the powder?

Card 3

Front

What is the general principle for DPIs? (1)

Back

Preview of the front of card 3

Card 4

Front

What is the general principle for DPIs? (2)

Back

Preview of the front of card 4

Card 5

Front

What is a single unit dose?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Pharmacy resources:

See all Pharmacy resources »See all DPIs resources »