The Skin - Transdermal Drug Delivery W5 Flashcards
Transdermal drug delivery
Delivering drugs across the skin and into the systemic circulation
Transdermal skin patches
The patch is worn on the skin, and over time, it releases the active pharmaceutical ingredient (API) at a controlled rate.
This method bypasses the digestive system and liver metabolism (the first-pass effect), delivering a consistent dose of medication.
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
The two main types of transdermal skin patches are:
- Reservoir-Type Patches
- These patches consist of a reservoir that holds the drug, which is then released at a steady rate. The drug is typically released over a specific period of time, ie fentanyl - Matrix-Type Patches
- These patches contain the drug embedded in a solid polymer matrix. The drug diffuses out of the matrix at a controlled rate as the patch is worn, ie nicotine
Microneedle delivery of therapeutic macromolecules
involves the use of tiny needles to administer macromolecular drugs through the skin.
is especially beneficial for large, complex molecules such as proteins, peptides, vaccines, and gene therapies that cannot typically be delivered by conventional methods like oral administration or normal injections due to their size, instability, or poor absorption.
needles are small enough to penetrate the skin and deliver drugs to the epidermis or dermis without reaching the nerve-rich layers, which is why they are pain-free.
Iontophoresis
deliver charged molecules, typically drugs, through the skin using a small electrical current.
This method is particularly useful for water-soluble and charged compounds, which otherwise would have difficulty penetrating the skin’s stratum corneum
