Transdermal Drug Delivery System

A medicated adhesive patch that is placed on the patient’s skin to deliver a specific dosage of medication through the skin is referred as a transdermal patch. The drug that is administered through the skin surface travels through the skin into the bloodstream. Transdermal drug delivery patches promote healing of an injured area.

The transdermal patch makes use of a special membrane to control the rate at which the liquid form of drug present in the reservoir within the patch can pass through the skin into the bloodstream. In few cases, alcohol is used along with the drug to increase their ability to penetrate the surface layer of the patient’s skin.

Drugs administered through Transdermal patch or Skin Patch

The most common drugs that are administered through the skin patch include the following:

  • Scopolamine – for motion sickness
  • Nicotine – for quitting smoking
  • Estrogen – for menopause and for prevention of osteoporosis after menopause
  • Nitroglycerin – for angina
  • Lidocaine –  to relieve pain caused due to Herpes zoster infection
  • Insulin – for diabetes

The first transdermal patch was approved by FDA in 1979 and the skin patch that got approval was for motion sickness.

Advantages of Transdermal Patch

There are many benefits of using transdermal patches for drug delivery. The most common advantages include the following:

  • The administration of drugs is painless.
  • It is one of the common non-invasive ways to deliver a drug substance directly into the patient’s body.
  • No bulky drug delivery devices are required
  • Peak plasma levels of drugs are generally reduced to decrease the side effects
  • Drugs that enter through the skin can easily avoid the liver. The substances that are broken down by the stomach acids or degraded by the liver can easily be administered using transdermal patches.
  • It aids in a controlled and steady delivery of medications over a long period of time.
  • The side effects of transdermal patches are comparatively less than the oral medications.
  • It is the best alternative for the patients who cannot take supplements or drugs orally.
  • The skin patches are cost effective

Limitations of Transdermal Drug Delivery System (TDS)

Every drug delivery system has certain limitations. There are certain limitations for transdermal drug delivery system. They are:

  • High drug levels cannot be achieved in the blood/plasma using TDDS
  • TDDS cannot deliver ionic drugs
  • TDDS cannot be used for drugs of large molecular size
  • The drugs that cause irritation to the skin cannot be developed through TDDS.

Conditions in which Transdermal patches are used

There are three conditions that require the use of TDDS.

  1. When the patient is unable to take oral medications or has intolerable side effects like constipation.
  2. Patients with cognitive impairment can also be given the dosage through TDDS.
  3. To produce a certain synergistic effect, TDDS can be used in combination with other enhancement strategies.

How to use TDDS?

Care need to be taken while applying the transdermal patch on the patient’s skin. The following points need to be kept in mind:

  • The part of the skin must be cleaned properly before applying the patch
  • The patch should not be cut as it can completely destroy the delivery system.
  • The old patch need to removed, before applying the new patch
  • Care must be taken while applying and removing the patch as the drug can be absorbed through the skin of the individual handling it.
  • Accurate application of the patch is necessary.

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