In this article we share the most important advantages that transdermal patches have over other dosage forms and routes of administration.
Transdermal patches are pressure sensitive adhesives that through the skin administer drugs into the systemic circulation throughout to the site of action. Some of its advantages are:
● Controlled and constant administration
● Improved therapeutic bioavailability
● Easy application
● Improved patient compliance
Learn in the following lines how the transdermal patch can help overcome the drawbacks associated with other routes of administration, such as oral and intravenous, while improving the effectiveness of therapeutic treatment.
Since the beginning of time, different cultures have explored the administration of medicines through the skin. It is known that ancient populations in Africa applied plants and minerals to treat dermis conditions.
Over the centuries, various topical products such as creams, gels, plasters, ointments and lotions have been developed. These only act locally on the first layers of the skin (stratum corneum and epidermis).
In 1979, the development of transdermal pharmaceuticals took a quantum leap with the Food and Drug Administration’s (FDA) approval of the first scopolamine patch to treat motion sickness at sea. A novel system consisting of an adhesive pharmaceutical product that delivers a specific and controlled dose of a therapeutic drug through the patient’s skin. An effective, high-quality and safe method that has multiple advantages.
In the last decades, there have been important advances. To date there are 23 FDA approved patches, which treat a wide range of conditions and diseases such as chronic pain, hormone replacement, Alzheimer disease, Dementia associated with Parkinson disease, attention deficit hyperactivity disorder (ADHD), to name a few.
Currently, work is underway to develop novel adhesives, nanoparticles and chemical permeation enhancers to improve drug solubility with the aim of expanding this list.
These are some of the advantages offered by this form of administration:
Transdermal patches have just the right dose of active pharmaceutical ingredient (API) and its administration is:
● Constant: The system is designed to deliver the drug at a constant rate to obtain a blood concentration and maintain it until the system is withdrawn. After patch removal, the blood concentration decreases at a rate consistent with the pharmacokinetics of the drug.
● Controlled: The skin is the membrane that controls the rate at which the drug enters the body. The total duration of API release and dose from the system used and the patch surface can also be indicated. This is expressed as mass per unit time for a given surface area.
Administration through transdermal patches optimizes the amount and speed at which the API is absorbed by the body and becomes available at the site of action. Because the patch transports the drug into the bloodstream bypassing the gastrointestinal system and the first-pass metabolism in the intestine and liver.
For example, through oral administration, the drug may be degraded upon entering the gastrointestinal tract due to an enzymatic reaction or by exposure to the stomach environment. Its solubility in the liquid of the intestine and its permeability through its membrane can also be a limiting factor.
The administration of the drug by means of the transdermal patch is very advantageous compared to the oral or intravenous route, especially because it offers greater comfort to the patient.
Although oral administration of medications is the most frequent, in some occasions it may be unviable. Such is the case of people:
● With difficulty swallowing (Dysphagia)
● Who experience intolerance to the drug in the process of metabolization
● Who are asleep, unresponsive, or unable to swallow oral medications
Intravenous administration, on the other hand, has a precise dosage and, when introduced into the bloodstream, also avoids hepatic metabolism. However, it causes pain and discomfort for the patient, in addition to the costs associated with the management of pathogenic waste generated by its use.
One of the enormous advantages offered by this system is the easy application of the patch and self-administration. It does not require expert personnel for its placement, as is the case with the intravenous route.
It is only necessary for the patient to adhere the transdermal patch to the prescribed area according to his therapeutic needs. It can be on the chest, buttocks, abdomen, upper torso or upper outer arm. It is only required that the site of application should be intact (not injured or wounded), clean, free oily and hairless.
In the event of adverse reactions such as itching, irritation or erythema, it is just necessary to remove the patch to stop the drug delivery. This makes this system safe even when there is an intolerance to the administered API.
The simplicity of the system helps to improve compliance with therapeutic treatment.
● There is no risk of forgetting to take the medication, as is the case with oral administration.
● It avoids accidental overdoses, since the dose of the drug is determined in the system.
● It does not require assistance for the application of the drug as in the case of an intravenous injection.
In conclusion, transdermal patches are the result of years of research that respond to the need for more effective therapeutic treatments, while providing greater comfort and safety for the patient.
Although this system currently has a limited drug list, researchers and developers are actively working to expand it in the near future.
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