The Skin - Transdermal Drug Delivery W5 Flashcards
Transdermal drug delivery
Delivering drugs across the SC and into the
systemic circulation
Transdermal skin patches
Greatest advance in transdermal drug
delivery
Transdermal therapeutic system (TTS)
◦ Designed to release drug at a rate below the maximal rate for controlled systemic therapy
Transdermal skin patches advantages
Advantages:
◦ Avoids first-pass metabolism of drug in liver
◦ Consistent site of absorption i.e. no missing gut absorption window
◦ Can give constant drug input rate
◦ Can stop dosing by removing patch
Types of transdermal skin patch
Two main categories:
- Monolith (matrix) system
- Rate-limiting membrane system
Monolith (matrix system)
◦ Drug present as suspension
Microneedle delivery of therapeutic macromolecules
Large drug molecules like peptides/proteins are
too large and hydrophilic to diffuse through the
skin
Peptides/protein rapidly degraded in GI tract. Skin has much less enzymatic activity
Stratum corneum defence can be breached by
arrays of microneedles
Tiny (invisible) needles penetrate into epidermis
but not as far as nerve fibres
Iontophoresis
Driving of charged molecules through the skin
using low electrical currents (0.5mA/cm2)
Small current applied across the skin
Glycopyrronium bromide used for
hyperhidrosis