The Skin - Transdermal Drug Delivery W5

Question 1

Transdermal drug delivery

Answer 1

Delivering drugs across the SC and into the
systemic circulation

Question 2

Transdermal skin patches

Answer 2

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

Question 3

Transdermal skin patches advantages

Answer 3

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

Question 4

Types of transdermal skin patch

Answer 4

Two main categories:
- Monolith (matrix) system
- Rate-limiting membrane system

Monolith (matrix system)
◦ Drug present as suspension

Question 5

Microneedle delivery of therapeutic macromolecules

Answer 5

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

Question 6

Iontophoresis

Answer 6

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