Transdermal Drug Delivery Flashcards
Describe the structure of the stratum corneum
Dead anucleated keratinised cells embedded in a lipid matrix “Brick and mortar”
What are the 3 pathways for drug delivery to the skin?
Transcellular (or intracellular)
Intercellular
Trans appendageal pathway (shunt route)
What is the rate limiting step in transdermal delivery
Movement across the stratum corneum
6 ideal characteristics of drugs for ttdd
- low molecular mass (<500Da)
- balanced logP between 1 and 4, ideally between 2 and 3
- low melting point - indication of drug solubility
- potent drug - <10mg/day
- adequate solubility in oil and water
- acceptable toxicity profile
Name 2 manufacturing processes to develop patches
Extrusion process
Solvent casting
Which manufacturing process should be used to develop thermolabile drugs
Solvent casting
Name polymers used in backing layer
EVA
Polyethylene
Name excipients used in patches
Plasticisers
Penetration enhancers
Name polymers used in adhesive layer
Acrylates
Polyisobutylene
Silicones (polysiloxane)
Rubber based
Name polymers used in release liner
Silicone or fluorocarbon coatings on paper
Polyester or polycarbonate films
Name polymers used in rate controlling membrane
EVA copolymers
Microporous Polypropylene
Polyethylene
can you cut ttds reservoir systems
no
what is the thermodynamic state of the drug and polymer in a matrix system?
Drug suspension is in equilibrium with its saturated solution (maximum thermodynamic activity)
What is the equation for calculating lag time
L = h(2) / 6D
What is Nitro-dur?
it is an example of a drug in adhesive system containing nitroglycerin
what type of ttds is Scopolamine?
rate controlling membrane
what type of ttds is clonidine?
reservoir
what combined drugs are given for hormone delivery
norelgestromin
ethinyl oestradiol
what matrix type is used for hormonal delivery
polyisobutylene/ polybutene adhesive
What drug does Neupro contain?
Rotigotine - dopamine agonist
Indication of Neupro
Parkinson’s disease
What drug is in Durogesic DTrans
Fentanyl
Not for opioid naive patients
Indication of Daytrana
ADHD
what drug is in Daytrana
Methylphenidate
