Transdermal Drug Delivery

Injections are an effective way of administering drugs to patients in need. Now, for some types of drug treatments– delivering insulin to diabetics, for example, or vaccinations to especially those suffering from chronic  conditions– microneedle patches offer an alternative option for drug delivery.

Researchers have been looking at the use of tiny microneedle patches as an alternative for drug and vaccine delivery. The patches, about the size of a fingernail, contain rows of microneedles. When the patches are applied to the skin, the microneedles penetrate the skin’s top layer, enough to administer the medication in the patch into a person’s system.

Patches have been used for drug delivery for many years. Nicotine patches are probably the most familiar example. But for larger-molecule substances, such as insulin, this type of patch did not work initially.

The skin’s anatomical peculiarities make it difficult to cross with the skin’s stratum corneum, the outermost layer, being the major barrier. However, the layer underneath, the viable epidermis, also plays a protective role.

According to research published in Pharmaceutics, only compounds that are able to get through the stratum corneum and diffuse through both layers of the epidermis have the potential to reach a person’s circulation and achieve systemic effects.

Patches with microneedles may offer a solution. The microneedles penetrate those outer layers but stop short of reaching the pain receptors and blood vessels beneath. It is an optimal subcutaneous region to facilitate drug delivery since patients will not feel any pain because the needles in the patches do not go that deep.

Using medical silicones, whether in the form of compound or in the form of liquid silicone rubber (LSR) in microneedle patches bears a series of advantages. It’s an inert material, biocompatible and proven over decades to not cause skin irritation and be generally tolerated by the human body. The special characteristics of LSR allow the production of very delicate, tiny features and components or thin film to lend it perfectly to microneedle patches. It’s generally porous structure lends itself perfectly to design it for the storage and release of drugs or vaccines.

Within the current state of advanced microneedle patch development, LSR is seen to serve a useful purpose as a carrier of drugs as well as of the very precise microneedle structure, each of these associated with unique manufacturing challenges. Likewise, LSR can effectively be used in the form of a protective element across the delicate microneedle structure prior to its application on the skin.

Learn more about LSR for medical applications

Trelleborg Medical Solutions has decades of experience using liquid silicone rubber (LSR) technology to create sealing solutions for the medical, life sciences, biotech and pharmaceutical industries.

Our engineers work jointly with medical device developers and manufacturers to design, produce and supply highly engineered components for drug delivery systems that include microneedle patches. Unique capabilities include:

The market for transdermal drug delivery, which includes but is not limited to microneedle patches, was valued at USD 8.9 billion in 2018 and is expected to reach USD 24.3 billion in 2025, according to MarketWatch. Over time, experts predict the FDA will approve many more types of microneedle patches.

Microneedle Patches

Size: The typical patch is the size of a fingernail or smaller, but it could take any size and shape, depending on the type of drug and dose being administered.

Microneedles: About the width of a human hair with a length of 25 to 2,000 microns. A micron is one-millionth of a meter.

How they work: Can be applied like any bandage. Needles penetrate only the outermost layer of the skin, the stratum corneum.

They can be divided into four types:

• Hollow: These infuse a drug through the bores with adequate flow.
• Solid: These puncture holes in the skin to increase permeability, allowing a drug to then be delivered.
• Coated: These are coated with a drug-containing dispersion.
• Polymer: These are made from special polymers that offer dissolving, non-dissolving or hydrogel-forming options.