What is the Difference Between Transdermal and Intradermal?

The main difference between transdermal and intradermal drug delivery lies in the skin penetration depth and the administration route. Here are the key differences:

• Transdermal drug delivery:
• Drugs are directly applied onto the intact and healthy skin.
• The target site is systemic distribution, as the drug penetrates through the skin layer and reaches the systemic circulation or deeper underlying tissues.
• Transdermal drug delivery is painless.
• It bypasses the liver's first-pass metabolism, reducing the risk of gastrointestinal system damage compared to the oral route.
• However, some adverse effects include skin reactions like pruritis, burns, and redness of the surrounding area.
• Intradermal drug delivery:
• Drugs are directly injected into the outer layer of the dermis, underneath the upper skin layer.
• The target site is in the dermis itself.
• Intradermal drug delivery is a painful administration route.
• It is largely controlled by the physiology and transport properties of the lower skin layers.

In summary, transdermal drug delivery involves applying drugs onto the skin for systemic distribution, while intradermal drug delivery involves injecting drugs directly into the outer layer of the dermis. Transdermal delivery is painless, while intradermal delivery can be painful.

Comparative Table: Transdermal vs Intradermal

Here is a table comparing the differences between transdermal and intradermal drug delivery routes:

In summary, transdermal drug delivery involves applying medication to the skin, where it penetrates through the skin layer and reaches systemic circulation or deeper underlying tissues, while intradermal drug delivery involves injecting medication directly into the outer layer of the dermis underneath the upper skin layer.