Some patients use 'color' to express their understanding of the type of patch, such as' I prefer brown patches! 'or' Isn't it a white patch? 'From the perspective of a professional pharmacist, these patches can be classified as' patches' or' ointments, 'but what are the specific differences between them? This time, let's take a look at the difference between "patches" and "ointments".

In a nutshell

The difference between patches and ointments=the difference in adhesive strength.

According to the Japanese Pharmacopoeia, in topical formulations suitable for the skin, "patch" is defined as "patch using almost no aqueous matrix", and "patch" is defined as "patch using an aqueous matrix". The reason why the plaster is a bit cool when applied is because it contains a high proportion of water. If the active ingredients are the same, then using any type of patch can achieve the same effect, but this time we will introduce the differences from a formula perspective.

Detailed explanation of specific differences

(1) Differences in adhesive strength

It is reported that compared with Mohrus patch and Mohrus gel patch containing the same dose of ketoprofen, "patch" shows absolute advantage in "adhesive strength" 2). Therefore, in joints with a wide range of motion such as the elbow and knee, solid application performance is required, and "patches" are a more ideal choice.

(2) Differences in application frequency

Comparing the statutory instructions and usage of various patches, it can be summarized as follows:

There are many once a day "patches" and twice a day "patches", but there is no significant difference between them. It can be said that this application frequency is the result of clinical trials. For the active ingredient is "Loxoprofen Sodium" patch, "patch" and "plaster" 3) the migration and transportation to the Stratum corneum of the skin is the same, but for the active ingredient is "ketoprofen" patch, "patch" is applied once a day, which can transfer the drug through the Stratum corneum of the skin faster 4).

However, one ketoprofen gel patch (XR type) is applied "once a day" instead of twice a day. From the perspective of medication compliance, "because it is difficult to change the patch" and "there is no leisure time to change the patch", the formula of "patch" is designed to be applied once a day. Compared with ketoprofen patch (L-type) 05), the composition and effect of active drugs transported to the Stratum corneum of the skin are the same.

3. Differences in auxiliary materials

The initial use of "patch" was a mud like matrix called "kaolin", and the drug must be applied on gauze beforehand. However, due to the residual matrix on the skin when removing the patch, administration is very inconvenient. At present, the mainstream excipient matrix is the network polymer gel composed of "Sodium polyacrylate and aluminum salt", which has the advantage of easily retaining a large amount of water and active drug ingredients. In addition, pharmaceutical companies have developed a new "acrylic adhesive" with less interaction between the substrate and the drug, making it possible to make patches with more active pharmaceutical ingredients.

The substrate of the patch includes rubber, acrylic acid, and silicone salts, which can be divided into matrix type and reservoir type. However, among the patches currently sold in the Japanese market, the only ones with systemic effects are those with storage structures, which control human blood drug concentrations through drug containing matrices, controlled release membranes, etc.

4. Extension Content

The patches mainly act locally, and there are also a few patches that can produce the aforementioned "systemic release" on the market. DDS (Drug Delivery System) technology is used to control the pharmacokinetics of drugs to improve treatment effectiveness and reduce side effects, and various technological branches have emerged in this field.

The microneedle does not touch the dermis where blood vessels and nerves are located. It is suitable for delivering a wide variety of drugs with a large molecular weight range, reducing the pain of patients during the administration process. Currently, soluble microneedles that directly transport hyaluronic acid into the skin are marketed as cosmetics. A Japanese manufacturer also launched the production, manufacturing, and marketing of this dosage form in June 2022. Recently, pharmaceutical companies have attempted to combine this soluble microneedle with influenza vaccines and complex drugs to develop clinical formulations.