Transdermal Drug Patches
When you think of medications you usually think of oral dosage forms or injection. The latest way of taking your medication is by transdermal or skin patch. Oral medications are swallowed, but the digestion can affect how they are absorbed and may cause stomach irritation. With injections, the drug action is faster and sometimes shorter, but can be inconvenient.
Transdermal patches avoid the digestive tract completely and the drug is slowly absorbed across the skin directly into the circulation resulting in a long lasting effect. Nicotine patches were the first available in the late 1970’s, and since then other drugs have been manufactured as patches for menopause, chest pain, severe pain and for motion sickness.
Using patches is convenient and easy and produce more even blood levels of a drug, because the drug is constantly diffusing from the patch into the circulation. While patch technology would seem to be an ideal drug delivery system, more drugs are not available as patches because the drug molecules need to be small enough to be absorbed this way, for example the insulin molecule is too large.
If you use a transdermal patch, here are a few hints to improve your success rate:
- The most common adverse reaction is skin irritation - when you begin using your patch, test it on your skin for any redness, rash, itching and check with your health care provider if any of these symptoms are seen.
- While cutting a patch may make economic sense, cutting patches may result in the drug “leaking out”. Check with your Pharmacist first.
- Apply patches to clean, dry skin. Wash the skin with soap and water, rinse and dry well.
- If the patch won’t stick, try wiping the area with a little rubbing alcohol, letting the skin dry, and then applying the patch. Avoid skin care products that can leave a greasy film on the skin.
- Sometimes a patch is recommended to be applied to a specific area - you will need to read the instructions. Patches should not be applied to areas where they may be rubbed off, for example the waist, a skin fold.
- Patches tend not to stick to hairy areas - avoid these if possible. If needed, clip the hair with scissors; don’t shave it as the patch can irritate the just shaved skin.
- Make sure your hands and skin are dry when applying a patch. If the adhesive gets wet, it is less likely to stick.
- When you put the patch on, gently rub it to remove air bubbles. The warmth from your hand may also improve the stickiness of the adhesive.
- If a patch falls-off, some patches can be reapplied if all of the patch can be stuck to the skin surface, others need to be discarded.
- Remember to remove the old patch before applying a new one.