Formulation of Advanced or Complex Medicines 29 Flashcards
What are the properties of ideal penetration enhancers?
Non-toxic
Non-allergenic
Non-irritating
Non-pharmacological
Bland
Cheap
Stable
Compatible
Unidirectional
Rapidly acting
Give examples of penetration enhancers
Azone and related compounds
Solvents, alcohols and related compounds
Fatty alcohols, fatty acids and related structures
Fatty acid esters
Dimethyl sulphoxide and related compounds
Water
How can penetration be physically enhanced?
Occlusion
- any form of covering will enhance penetration
What is a matrix patch?
An inert, adhesive polymer matrix binds with the drug and controls release
What is a reservoir patch?
Polymer matrix does NOT control drug release
A rate controlling membrane present between the drug matrix and the adhesive layer provides the rate-limiting barrier for drug release from the device
What is the structure of a Nicorette patch?
Occlusive outer layer composed of laminated polyester film
Nicotine dispersed in structural non-woven material and rate-limiting adhesives
Disposable liner
What is the structure of a Nicotinell patch?
Tan coloured aluminised backing film
Pressure sensitive acrylate adhesive
Reservoir layer
- methacrylate acid co-polymer solution of nicotine dispersed in a pad of viscose and cotton
Removable protective liner
Give examples of vesicular or nanoparticle delivery
Carrier molecules
Liposomes
Transfersomes
Ethosomes
Niosomes
Nanoparticles
What is iontophoresis?
Migration of ionic drugs into skin using a physiological acceptable DC electric current
- direct
- pulsed
Drug is pushed into the skin by electrostatic repulsion
How can iontophoresis be enhanced?
Enhanced delivery through electrorepulsion, electro-osmosis or current induced skin permeability
How is the circuit completed in iontophoresis?
Physiological counterions complete the circuit
What is magnetophoresis?
Application of a magnetic field enhances transdermal delivery of poorly permeable drugs
- altering the barrier properties of the stratum corneum
- magnetokinesis
- octanol/water partition co-efficient of drugs increases when exposed to magnetic field
What is a jet injection?
Device for physically pushing drug into skin from the surface
How does jet injection work?
Devices include compressed gas, a compartment containing particulate drug formation (and carrier) and a nozzle to direct flow
Propelled particles puncture micron-sized holes through stratum corneum by virtue of their momentum and density
- gold coated
- heavy metal so more momentum
Clinical trials have reported painless delivery at the time of injection
- DNA vaccines well tolerated
How does radiofrequency work to deliver drugs?
Viaderm creates microchannels through radiofrequency ablation
- demonstrates utility for pDNA delivery to skin, clinical data on granisetron, insulin, hPTH and hGH
