Therapeutic Aerosols

Question 1

Describe what an aerosol?

Answer 1

• fine suspension of liquid/solid particles in a gas

Question 2

Within a pharmacy - what is an aerosol?

Answer 2

Self-contained, sprayable product operating under pressure of a liquefied/compressed gas propellant.

Question 3

What are aerosols used for?

Answer 3

Used for topical treatments and administration to body cavities

Question 4

Do nebulisers and dry powder inhalers use propellant?

Answer 4

No

Question 5

What are the advantages of aerosols?

Answer 5

• convenient
• efficient dispersion of drug
• immediate application
• no contamination of contents
• sealed canisters exclude light, air and moisture
• uniform dose with paid response
• drug delivered in high conc to limited areas

Question 6

What are the disadvantages of aerosols?

Answer 6

• expensive production
• disposal problems
• must be kept cool
• propellant can cause discomfort
• propellant may be toxic on inhalation
• formulation difficulties of drugs are insoluble in propellant
• stability problems with certain material used in packaging

Question 7

What are the topical uses for aerosols? Give examples

Answer 7

local analgesics - cooling effects
local anaesthetics e.g. lidocaine
antiseptics and skin sterilisers e.g. chlorhexidine
anti inflammatory agents e.g. hydrocortisone
anti pruritics (anti itch) e.g. benzoin
fungicidal, anti-parasitic and antibiotics - treat fungal infections
skin dressing e.g. acrylic resin polymers

Question 8

How are aerosols administrate to the body cavities? Give examples.

Answer 8

ear - otomize
nose - otrivine 
throat - chloraseptic 
mouth - eludril 
lungs - asthma - inhalers 
rectum - perinal

Question 9

What are two types of simple aerosol?

Answer 9

liquefies compressed gases

compressed gases

Question 10

what is the two phase system of liquefied compressed gases?

Answer 10

liquid - propellant with soluble drug

vapour - vapour from propellant

Question 11

describe liquid compressed gases

Answer 11

• propellant have increase vapour pressure which is the measure of tendency to evaporate
• gases chosen are high volatile - high tendency to evaporate
• propellant become vapour - squeeze into headspace - increase pressure
• empty space filled with gas, increase pressure, when valve opened - contents goes out - after liquid becomes gas, fills empty space again. increasing in pressure and content can go out again
• process continued liquid turns to vapour - pressure increases

Question 12

describe compressed gases

Answer 12

• insoluble gases - simple gas canister - gas occupies space - increase pressure
• pressure too low = content not expelled
• no equilibrium