by What are Transdermal Skin Patches?
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 passing drugs through the various layers of the epidermis (upper or outer layer) and dermis (inner or lower layer) of the skin and into the bloodstream. The medication is then delivered from the bloodstream throughout the body.
How do Transdermal Skin Patches Work?
Transdermal skin patches work through a process known as transdermal delivery. In this process, medication in the adhesive matrix or gel reservoir of the patch passes through the various layers of the skin and enters the circulating bloodstream. For drugs to be delivered via this route, they need to have certain properties like appropriate size and dosage, adequate solubility and permeability through the layers of the skin. The active pharmaceutical ingredients (APIs) used in transdermal patches are usually lipophilic in nature, enabling them to permeate through the lipid-rich layers of the epidermis.
The patch is designed in such a way that the medication is released slowly from the matrix or reservoir at a predetermined rate over an extended period, ranging from a few hours to even a week or more. This ensures that a consistent level of the drug is delivered to the systemic circulation to achieve the desired therapeutic effect. The rate of absorption depends on various factors like the condition of the application site, drug properties, characteristics of the adhesive matrix as well as the patient’s physiology.
Types of Transdermal Skin Patches
Transdermal patches are available in different types based on the mechanism used for drug delivery:
– Matrix patches: These contain the active ingredients evenly dispersed within an adhesive polymeric matrix. The medication diffuses through the matrix and skin at a controlled rate.
– Reservoir patches: Here, the active ingredients are enclosed in a cavity or reservoir within an impermeable backing layer. A rate-controlling membrane regulates the release of drugs from the reservoir into the adhesive matrix and skin.
– Microporous membrane patches: These utilize a microporous membrane saturated with the drug. The medication permeates through the pores and skin.
– Monolithic matrix patches: In these, the drug is contained within a single, homogenous adhesive matrix layer sandwiched between backing and release liners.
Based on the therapeutic usage, Transdermal Skin Patches can be categorized as contraceptive patches, nicotine patches, hormone replacement patches and analgesic patches among others. Each type is designed to administer a specific drug for its intended application.
Advantages of Transdermal Skin Patches
The transdermal route of drug delivery offers several benefits over oral and injectable modes:
– Sustained release of medication: Patches enable continuous release of drugs into the systemic circulation over extended periods, maintaining steady drug levels in the body.
– Avoid first-pass metabolism: Since drugs avoid digestion and bypass the liver, the intensity of the first-pass metabolism is reduced. This improves bioavailability.
– Improved patient compliance: Once-a-week or once-a-month patch application promotes better treatment adherence than multiple daily pills.
– Non-invasive route: Skin patches provide a convenient and painless alternative to injections. This boosts acceptability, especially for drugs meant for long-term use.
– Termination of drug delivery: Application can be readily terminated by removing the patch if any adverse effects occur.
– Self-administration: Patches are easy to apply and remove without assistance from healthcare professionals.
Some potential drawbacks include local skin reactions, issues with adherence, lack of patient control over dosing and prohibitive cost of some advanced patch technologies. However, these downsides are minor relative to the clinical benefits.
Application and Placement of Transdermal Patches
Transdermal patches are usually applied to clean, dry, healthy, hairless regions of the skin where blood circulation is optimal for absorption. Common application sites include upper arms, chest, back, upper outer areas of buttocks and shoulders. The steps involved are:
1. The selected area is cleaned with plain water and dried thoroughly.
2. The protective backing is removed from one side of the patch.
3. With the adhesive side facing the skin, the patch is pressed gently onto the application site with the fingers and rubbed to enhance contact.
4. The other protective covering is then peeled off.
5. The patch should not be applied over areas with skin conditions, injuries or excessive hair.
6. Optimal adhesion is essential for consistent drug delivery. Application site should avoid areas prone to excessive sweating, rubbing or moisture.
7. Patches may be washed, showered or bathed with while on. But must avoid soaking in water for long.
8. Unless otherwise instructed, patches are usually replaced after 7 days and applied on a different site each time.
9. Hands should be washed after application or removal.
Dosage, Safety and Side Effects
Depending on the drug formulation, a single transdermal patch may contain enough medication dosage for anywhere between 2-7 days. The patient follows the prescribed usage and changing schedule as directed by their healthcare provider. Some elements to keep in mind dosage and safety wise are:
– Strictly adhere to prescribed dosage, frequency of patch changes and application instructions for optimal effect and safety.
– Avoid sun exposure of application sites for some medications like contraceptive patches which may get degraded due to UV light.
– Notify the doctor immediately about any adverse effects or issues with patch adhesion, so that dosage or medication can be adjusted accordingly.
Common mild local skin reactions include redness, itching, irritation and small rashes at the application site, which typically subside over time. Systemic side effects depend on the specific drug administered via the transdermal route and are usually similar to those experienced via oral forms. Serious issues are rare with proper usage as per prescription. Regular medical follow-ups also help address any emerging safety concerns.
In summary, transdermal skin patches present an advantageous option for sustained delivery of many different medications. They provide improved bioavailability and patient acceptability over oral administration while being more convenient to use than injections. With consistent therapeutic levels attained over extended periods, transdermal patches have proven efficacy in various therapeutic areas from contraception and hormone replacement to pain management and nicotine cessation support when dosed as prescribed. Precise formulation technologies ensure optimal adhesion, drug release kinetics and tolerability profiles for maximizing clinical benefits of each patch.
Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
