Transdermal Patches and Medications

A transdermal patch delivers medication through the skin into the bloodstream, no needle and no swallowing. It bypasses first-pass metabolism and the GI tract, which makes it a good option for patients who cannot swallow pills and helps with compliance.

What Are Transdermal Medications?

Transdermal medication is delivered through the skin for systemic effect, via a patch that releases the drug slowly and at a controlled rate into the bloodstream.

How the Patch Works

Layers:

• Backing layer protects the patch from the outside.
• Drug reservoir or matrix holds the medication.
• Release liner protects the drug in storage and peels off before use.
• Adhesive layer sticks it to the skin.

The drug releases at a controlled rate, crosses the skin layers (stratum corneum, epidermis, dermis), and enters the capillaries for systemic distribution.

Advantages

• Controlled release over time.
• Noninvasive, no injection pain or infection risk.
• Bypasses the digestive tract, avoiding stomach acid.
• Bypasses first-pass liver metabolism, delivering more directly to the bloodstream.

Disadvantages

• Local skin reactions, irritation or allergy at the site.
• Variable absorption by individual and by site.
• More expensive than oral medications.
• Limited drug types. Only small, lipophilic molecules deliver well transdermally.

Types of Patches

1. Single-layer drug-in-adhesive. The adhesive layer is both glue and drug reservoir. Simple and easy to make.
2. Multi-layer drug-in-adhesive. Multiple adhesive layers, each with drug, for more controlled release; layers can carry different concentrations.
3. Reservoir. A separate drug reservoir between a backing layer and a rate-controlling membrane, for precise, prolonged delivery.
4. Matrix. The drug sits in a matrix layer between backing and adhesive, diffusing out for a steady release.
5. Vapor patches. Release essential oils or substances that vaporize and are inhaled rather than absorbed; common in aromatherapy.
6. Micro-reservoir. Combines reservoir and matrix: tiny drug reservoirs in a gel-like matrix for controlled, sustained release.

Drugs Given by Patch

• Pain relievers: fentanyl (Duragesic), buprenorphine (Butrans)
• Hormones: estrogen (Estraderm, Vivelle-Dot), testosterone (Androderm)
• Cardiovascular: nitroglycerin (Nitro-Dur, Transderm-Nitro), clonidine (Catapres-TTS)
• Neurological: rivastigmine (Exelon), rotigotine (Neupro)
• Smoking cessation: nicotine (Nicoderm CQ, Nicotrol)
• Antidepressants: selegiline (Emsam)

Side Effects

• Local skin reactions: redness, itching, rash, or swelling at the site.
• Systemic effects depending on the drug: dizziness, nausea, headache, or drug-specific effects.
• Allergic reactions, rare but needing immediate attention.

How to Apply

1. Check the order or label for placement (upper chest, upper outer arm, lower abdomen, or hip) for even absorption.
2. Remove any old patch of the same drug, fold it sticky-sides together, and discard it. This keeps dosing consistent and prevents overdose and irritation.
3. Clean the area with clear water and pat it dry. No soap, alcohol, lotion, or oil, which interfere with adhesion.
4. Open the pouch and remove the patch without touching the adhesive side.
5. Press the adhesive side onto the skin with your palm right away for strong adhesion.
6. Hold firmly for at least 30 seconds, pressing the edges, so it adheres well.
7. Tape the edges or use a see-through dressing if it loosens.
8. If a patch falls off early, dispose of it, apply a new one, keep the original dosing schedule, and tell the physician or pharmacist.
9. Wash your hands with water right after applying.
10. At each change, use a different skin area.
11. Fold the used patch sticky-sides together and dispose of it properly.

Nursing Considerations

1. Pick a site that adheres well: clean, dry, hair-free, no sweat or cuts.
2. Rotate sites (upper arm, abdomen, hip) to limit irritation.
3. Mind skin thickness. Avoid skin that is very thin or very thick, which changes absorption.
4. Keep the patch dry, away from prolonged water or moisture.
5. Never apply a new patch over a previous site, which risks unintended interactions or overdosing.