Main contents and classification of research on external treatment of traditional Chinese medicine

The content of external treatment of traditional Chinese medicine is very rich. According to the relevant literature, there are more than 400 kinds of external treatment methods, which can be divided into two categories: drug external treatment and non-drug external treatment. The general treatment scope is divided into two categories: external treatment of internal diseases and external treatment of external diseases. Specifically, clinical external treatment is divided into internal medicine external treatment, surgical external treatment, gynecological external treatment and pediatric external treatment. In recent years, transdermal administration of traditional Chinese medicine belongs to the research category of external treatment of traditional Chinese medicine, which can be applied to the treatment of many clinical diseases.

With the development of the times, the external treatment of traditional Chinese medicine has added new contents. According to different classification methods, external treatment of traditional Chinese medicine can have different classification methods. The classification of external treatment of traditional Chinese medicine is helpful to clarify the object and goal of external treatment of traditional Chinese medicine. According to different treatment methods, TCM external treatment can be divided into four categories: holistic treatment, skin and mucous membrane treatment, meridian and acupoint treatment and other treatments.

(1) Holistic therapy refers to treating people as a whole, which mainly includes guidance, physical therapy and music therapy.

(2) The treatment of skin and Guan Qiao's mucosa refers to the method that drugs are absorbed through the skin and Guan Qiao's mucosa and enter the local or systemic circulatory system to play a therapeutic role, such as external application therapy and fumigation therapy. Transdermal drug delivery system (TDDS) or transdermal therapeutic system (TTS) in modern pharmaceutical pharmaceutics belong to this kind of treatment method. This preparation is commonly known as patch in Europe and America, and it is also often called patch in China.

(3) Meridian acupoint treatment refers to the treatment method of applying drugs, manipulations and instruments to meridian acupoints. Such as massage, moxibustion, umbilical therapy, foot heart therapy and so on.

(4) Other external treatment methods of traditional Chinese medicine that cannot be classified into the above three categories, such as some operations of traditional Chinese medicine and bone setting of traditional Chinese medicine, can be classified into this category.

The above classification methods can not completely separate all external treatments, and there are often overlapping classifications. This crossing is an important feature of the classification of external treatment. Traditional Chinese medicines include pills, powder, ointment, Dan, wine, dew, soup, drink, glue, tea, cake, ingot, thread, bar, nail, moxibustion, ironing, ointment and so on. Due to the inconvenience of preparation and use, some dosage forms are rarely used. As we all know, most of these formulas can be used for external treatment of traditional Chinese medicine. With the development of science and technology, the traditional dosage forms of traditional Chinese medicine are constantly innovating, and tablets, capsules, granules, aerosols, injections, films and so on have appeared. Most of these dosage forms can also be used for external treatment, such as injections for aerosol inhalation and rectal administration. With the further development of extraction, purification, concentration and drying technology of traditional Chinese medicine, the application of polymer materials and the continuous application of modern pharmaceutical preparation technologies such as microcapsules, microspheres, liposomes, microemulsions and micropowder in the research and development of traditional Chinese medicine, new dosage forms that can be used for external treatment of traditional Chinese medicine are also emerging. There are dozens of dosage forms suitable for the administration of five senses, nine orifices and lung mucosa, such as patches, buccal tablets, aerosols, sprays, powders, gels, liposomes, microspheres, nasal drops, ointments, foams, sponges, suppositories, micro-enemas, cataplasms for skin administration, etc. These same dosage forms for external treatment usually have multiple routes of administration and may appear in different types of administration many times.

Due to the characteristics of traditional Chinese medicine, there are some problems in the study of new dosage forms, such as: few people engaged in the study of active ingredients, few people engaged in the study of in-vivo process of preparations, and there are also problems such as the separation between pharmacists and biologists, not paying full attention to the traditional experience of traditional Chinese medicine, and adopting western philosophy to study traditional Chinese medicine. However, these new pharmaceutical preparations represent the development direction of external treatment of traditional Chinese medicine in the future. For the external treatment of drugs, it is a key link to make drugs enter the body effectively through the skin barrier. There are three main ways to promote penetration: one is the characteristics of the drug itself, solvent and liposome (carrier) encapsulation, the other is the application of physical penetration promotion method, and the third is the application of chemical penetration promotion method. Strictly speaking, the first route can also be attributed to the chemical infiltration promotion method.

(1) changes the properties of the drug, which makes the drug have higher affinity with the skin and is beneficial to drug absorption. Drugs can be dissolved in appropriate organic solvents, such as alcohol (ethanol), vinegar (acetic acid), edible oil (fat, ester) and so on. It is beneficial to the absorption of drugs, and can also be made into preparations that are easy to penetrate through the skin, such as microemulsion, liposome, carrier, etc. There are many traditional Chinese medicines with good permeability-promoting properties, so we can consider applying or adding these traditional Chinese medicines in clinical prescriptions [3].

(2) Physical penetration enhancement: it is to change the characteristics of skin or drugs by physical methods and promote the transdermal absorption of drugs. At present, the commonly used physical penetration enhancement methods include ion introduction, electroporation, laser micropore and ultrasonic introduction. In fact, heating cupping in our daily life can also promote drug absorption by changing skin characteristics. The latest research achievement of physical infiltration enhancement is the application of microneedles based on micro-manufacturing technology.

(3) Chemical transdermal enhancers: In addition to chemical means to change the properties of drugs and necessary chemical solvents, chemical transdermal enhancers are the focus of research on external treatment of traditional Chinese medicine at present. Early chemical penetration enhancers mainly included propylene glycol, dimethyl formate and dimethyl sulfoxide. Azone and terpenoids are the most commonly used now, as well as some volatile oils for external use. Because the same drug formula has different transdermal effects on different transdermal enhancers and the concentration of the same transdermal enhancer is different, it may be necessary to combine multiple chemical enhancers for different drug formulas. To study the optimal concentration of transdermal enhancers, it is not necessarily that the higher the concentration, the better.

Research on new chemical penetration enhancers is also in progress. In 2006, Chinese scientists discovered a short peptide composed of 1 1 amino acid, which can effectively help protein drugs penetrate the skin and promote the transdermal absorption of insulin in rats. It is found that this protein can temporarily open the skin barrier, and hair follicles may be transdermal channels. The research results were published in the journal Nature. Similar results can be used in the development of external treatment of traditional Chinese medicine.