therapeutic aerosols Flashcards
what is a therapeutic aerosol?
fine suspension of liquid or solid particles in a gas
•generally, particle size < 50 mm
an ‘aerosol’ often thought of as a self-contained, sprayable product operating under the pressure of a liquified or compressed gas propellant
what can an aerosol be used for?
Used for topical treatment and administration to body cavities
what kind of inhalers don’t use propellants?
nebulizers and dry powder inhalers
what are the advantages of aerosols as a dosage form?
- convenient
- efficient dispersion of drug
- immediate application
- drug delivered in high concentrations to limited areas
- uniform dose with rapid response
- no contamination of the contents
- sterility of contents maintained where necessary
- sealed canisters exclude light, air and moisture
what are the disadvantages of using aerosols as a dosage form?
- expensive to produce
- disposal problems
- must be kept cool
- formulation difficulties if drugs are insoluble in propellant
- propellants may cause discomfort
- propellants may be toxic on inhalation
- stability problems with certain materials used in packaging reacting with contents
what types of topical use can you have with aerosols?
1- local analgesics-eucalyptus oil
2-local anasthetics- benzocaine, lidocaine
3-antiseptics and skin sterilizers-chlorhexidine, benzalkonium chloride
4-skin dressings-acrylic resin polymers
5-fungicidal, antiparasitic and antibiotic agents
6-anti-inflammatory- hydrocortisone
7-anti-inflammatory (itch)-benzoin
where might you admisinster an aerosol to body cavities?
- ear e.g. Otomize® spray (dexamethasone, neomycin)
- nose e.g. decongestant sprays Otrivine® spray (xylometazoline)
- throat e.g. Chloraseptic® spray (benzocaine)
- mouth, oral antiseptics e.g. Eludril® spray (chlorhexidine)
- rectum e.g. Perinal® (lidocaine, hydrocortisone) for treatment of haemorrhoids
- lungs, mainly to treat asthma
what are the two types of propellant?
1-liquified compressed gases
2-compressed gases (not liquified).
what is the job of the propellant?
give pressure
which type of propellant has to be used in pharmaceutical industry?
liquid compressed gases
what type of gases would be used in liquid compressed gases?
highly volatile- flourinated hydrocarbons
what happens in liquid compressed gas propellant?
molecules of vapourised propellant squeeze into the headspace until pressure is constant
what is the difference in the two propellants
the volume taken out has no effect on the pressure in the liquid compressed gas propellant where as it does in the compressed gases and it decreases the pressure every time volume is removed.. not the same pressure every time
what happens to the propellant when it is in the air?
it undergoes flash vaporization and only the drug is left
if the drug is not soluble in the propellant what may we use to stablise it?
a co-solvent- this is a 2 phase system
