May 22, 2024

Transdermal Skin Patches: An Overview of Their Function and Applications

Transdermal skin patches, also known as transdermal patches, are medicated adhesive patches that are placed on the skin to deliver a dose of medication through the skin and into the bloodstream. They work by utilizing the upper layers of the skin as the route of administration to deliver drugs through the layers of the epidermis and directly into the bloodstream.

How Transdermal Patches Work

Transdermal patches work through a process known as transdermal delivery or transdermal absorption. In this process, the active pharmaceutical ingredient (API) in the adhesive patch formulation is absorbed by the cells and capillaries located in the dermis and diffuses into the general circulation. For transdermal delivery to occur effectively, the API must be able to diffuse through the hydrophobic layers of the stratum corneum, which forms the skin’s primary barrier. Most transdermal patches therefore contain APIs that are small, lipophilic drug molecules. The patches may also contain various permeation enhancers to facilitate better penetration of the API through the skin barrier.

Once applied to the skin, the Transdermal Skin Patches will deliver a controlled dose of the medication through the skin and into systemic circulation over a specified period of time, which can range from a few hours to up to a week. This sustained release of medication allows for convenient once-a-day or once-weekly dosing as compared to taking pills multiple times a day. The patch provides continual drug administration at predetermined rates, aiming to achieve steady therapeutic drug levels in the body.

Common Medications Delivered via Transdermal Patch

Some common medications that are delivered via transdermal patches include:

– Hormone replacement therapies: Transdermal patches are often used for menopausal hormone therapy and for conditions like menstrual-related symptoms. Patches deliver estradiol or estrogen alone or in combination with progesterone.

– Pain relief: Transdermal fentanyl patches are used for chronic, severe pain associated with conditions like cancer. Transdermal buprenorphine is used to treat chronic pain.

– Nicotine replacement: Nicotine patches are one of the most common methods for smoking cessation treatment. They provide controlled doses of nicotine without the other chemicals in cigarettes.

– Blood pressure control: Transdermal clonidine patches are used to treat high blood pressure and symptoms of opioid withdrawal.

– Motion sickness: Transdermal scopolamine patches are used for prevention of motion sickness during travel by sea, air, car, or other motion-provoking situations.

– Birth control: Oral contraceptive combinations of estrogen and progestin can be delivered through transdermal patches to prevent pregnancy.

Advantages of Transdermal Patch Drug Delivery

There are several potential advantages associated with transdermal patch drug delivery over other traditional delivery methods:

– Convenient once-daily or weekly dosing: Transdermal patches eliminate the need for multiple daily doses of oral medications and thereby improve adherence and compliance. This is especially beneficial for patients with difficult medical conditions or cognitive impairments.

– Noninvasive administration: Patches provide a convenient, painless method of administration compared to injections, intramuscular shots, or even oral pills. This improves tolerability and acceptance.

– Steady blood levels: Patches administer drugs at predetermined rates, which provides stable, sustained drug levels in the body for effective therapy over time without spikes or drops in concentrations.

– Avoid first-pass metabolism: With transdermal delivery, drugs bypass the gastrointestinal (GI) tract and liver, allowing the entire dose to enter systemic circulation. This prevents first-pass metabolism that can reduce drug bioavailability for some oral medications.

– Improved efficacy for some drugs: For certain classes of medications that breakdown in the GI tract or liver, transdermal delivery has been found to produce superior clinical outcomes due to a higher proportion of the active drug entering the bloodstream.

– Flexible application: Patches can be applied at home with ease and do not require direct medical supervision, improving convenience.

Potential Limitations and Disadvantages

However, transdermal patches also have some potential limitations compared to other delivery methods:

– Skin irritation at application site: Some individuals experience redness, itching, or rash from patch adhesives that can affect tolerability and adherence. Those with sensitive skin may be at higher risk.

– Limited drug choice: Not all drugs can be effectively administered through the skin due to factors like molecular size, stability, and lipophilicity. The range of medications that can be delivered via patches is narrower than with other routes.

– Cost: Development of stable transdermal formulations requires extensive research and costs which may drive up prices, making some patches more expensive than oral therapies.

– Influence of heat and other variables: Environmental factors like heat, cold, sweating or bathing can potentially accelerate or inhibit release of drugs from patches and impact steady dosing. Activity levels and skin conditions may also variably impact absorption.

– Pain from ripped-off patches: Removal of patches after extended wear can potentially cause pain or skin tearing if applied too tightly or adhered too long. Gentle removal is required.

– Storage and disposal requirements: Patches require special storage conditions and disposal in medicine collection units rather than with regular trash due to risk of chemicals leaching from adhesives.

1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it