The markets of the world are replete with medications designed to ease and/or cure the symptoms associated with thousands of conditions. Traditional medication delivery methods, such as pills, capsules, liquids, powders, and intravenous needles, are often inefficient or invasive and can lead to undesirable side effects. Amongst the newer methodologies for administration of medicines is the use of transdermal approaches, including gels and patches for the treatment of many of the more common ailments
What is transdermal drug delivery?
Transdermal patches comprise a method of delivering medication through the skin in a non-invasive manner.. During transdermal drug delivery, a patch is adhered to a patient’s skin. The patch contains the medication prescribed to the patient and is designed in such a way that the medication permeates the skin in a controlled fashion thus attaining more steady levels of the drug in the body. Patches are presently being marketed which can be worn anywhere from as little as eight hours to as long as seven days, depending on their therapeutic indication.. These patches are secured with adhesives, which are designed to adhere comfortably to the skin which in turn allows a patient to use the patches for as long as is indicated by his or her physician.
How do they work?
Transdermal patches are simple to use and constitute a simple albeit efficient idea for medication delivery. One side of the patch contains the medication, which is formulated into the skin contact adhesive. It is this side of the patch which is adhered to the skin.
A person’s skin is his or her largest organ. It covers and protects the body, regenerates when needed, and provides limited but essential permeation. The skin has three layers. The first layer is called the epidermis. The epidermis is the skin’s outermost layer. This is the layer that contains the stratum corneum which is the primary barrier of the skin to entry of foreign substances.. The epidermis is the layer upon which a transdermal patch is placed.
The second layer of the skin is called the dermis. It lies beneath the epidermis and contains connective tissue that gives the skin structure and strength. The dermis also contains sweat glands and hair follicles. This layer of skin transmits medication from a patch into the deepest layer.
The deepest and third layer of skin is called the hypodermis. It is deeper subcutaneous tissue and is made of fat and more connective tissue. This layer contains blood vessels which also reach into the dermis and epidermis. These blood vessels are important in the transmission of medication from a patch to the bloodstream.
As the layers of skin absorb medication from transdermal patches (trans meaning through and dermal referring to the dermis (skin)), the medication is absorbed via the blood vessels into the bloodstream. From there, the blood carries medication through the circulatory system and through a patient’s body.
What are the benefits versus traditional drug delivery?
Transdermal patches offer many benefits over traditional pill, powder, or liquid medication delivery methods. The first benefit of using patches is the method’s direct-to-bloodstream delivery while bypassing the liver’s metabolic activity. A patient’s body heat activates a patch, prompting it to begin releasing medication through the skin and into the bloodstream.
The second benefit of using patches is that medication is supplied gradually and constantly, rather than in a large, single dose. Patches utilize the skin’s natural barrier properties in order to achieve a constant permeation of the drug and achieve steadier blood levels as compared to injectables and most oral medications.
Another benefit of using patches is that their use allows a medication to bypass the acidic environment found in the digestive system. Traditional drug delivery requires a pill, powder, or liquid to enter the digestive tract, where it is broken down by acid in the stomach. This breakdown can be difficult on a patient’s digestive system, and it can result in diminished effectiveness of the medication taken. Also, because the medication bypasses the gastrointestinal tract, patches may also reduce the risk of side effects.
Additionally, patches are painless, eliminating the need for injections that can cause a patient irritation and discomfort. Patches are simply placed on the skin, worn for a prescribed period of time, and removed. This also makes them convenient. A patient can remove and replace a patch himself without an added trip to the doctor’s office for a shot.
What are the transdermal delivery methods?
Transdermal medication delivery is most often administered using a patch, as described above. However, there are other delivery methods proving to be effective for a variety of patients. One such method uses a technology called microneedles. Microneedles are just as they sound: very short needles coated with or containing medication that can be made to penetrate the skin and deposit the drug closer to where it can be absorbed into the bloodstream.. This transdermal delivery method is quick and effective, increasing the skin’s permeability and making it easier for drugs to be absorbed into the bloodstream.
A common method of transdermal medication delivery is the use of a transdermal gel. These gels are applied in set doses to the skin. Medication contained in the gel then permeates the skin and enters the bloodstream. Transdermal gels can be found in drugstores sold as topical ointments, and they are gaining credibility as an effective method of transdermal drug delivery.
What is the history of transdermals?
Perhaps the first use of transdermals can be found in ancient China, where medicated plasters were slathered on the skin and left to dry. The method was devised to allow a medication to have direct and constant contact with the skin. This is the basic premise shared by designers of patches and medications today. The first patch certified and accepted by the United States Food and Drug Administration was for a motion sickness patch. It was approved in 1979. Nicotine patches rose the profile of transdermal patches in the 1990s when it was approved for patient use. Since then, patches have been designed for a bevy of medications, including those used to treatment of Alzheimer’s disease, Parkinsons, and those to administer birth control.