Chinese patent medicine (CPM, or ) are herbal medicines in traditional Chinese medicine (TCM), modernized into a ready-to-use form such as tablets, oral solutions or dry suspensions, as opposed to herbs that require cooking (hot water extraction).
History
Traditional Chinese medication generally begins with a liquid extract of a mixture of prepared herbs (), produced by a long period of boiling in water or a mixture of water and alcohol. Some formulas require different extraction times for each herb, leading to a complicated sequence of adding ingredients. With formulas intended for internal use, the resulting decoction (Tang ) is typically drunk directly. Some classical formulas call for turning the decoction into a ready-made teapill (Wan or Dan) for easier use. Formulas intended for external use, such as the gou pi gao, calls for more involved post-processing.
Chinese patent medicine started as a simplified way to produce a decoction. In the 1950s, Japanese man Otozo Nagakura founded a business that makes Kampo medicine in granule form by dehydrating the extract liquid. Patients would simply re-hydrate the granules and drink the resulting fluid. Taiwanese man Xu Hong-yuan visited Nagakura's factory and was impressed by its convenience and efficiency, bringing the technology to Taiwan.
Xu Hong-yuan later also invented the single-herb "granules for use in combination", which grants similar convenience to customized prescriptions. (Per-patient formulation is emphasized in TCM.) Chinese use of single-herb granules is growingly common, but technically remains experimental.
In China The 1963 edition of the Chinese Pharmacopoeia lists more than 150 so-called "pre-made prescriptions" () in traditional liquid, paste, Wan () pill, and Dan () pill forms. The next edition of 1977 includes more obviously "modernized" forms: tablets, sprays, granules, and even injections.
Forms
Traditional forms A few forms used in standardized, ready-to-use traditional Chinese medicine are inherited from the classical works. These include extracted condensed pills called teapills, honey pills and water pills made from ground raw herbs, mixture of powders (San ), and paste (Gao ).
Teapills are usually small, spherical, and black. They gain their name because the herbs are cooked into a herbal tea to make the pills. Modern teapills are created from herbs extracted in stainless steel extractors to create either a water decoction or water-alcohol decoction, depending on the herbs used. They are extracted at a low temperature (below 100 degrees Celsius; 212 degrees Fahrenheit) to preserve essential ingredients. The extracted liquid is then further condensed and a small amount of raw herb powder from one of the herbal ingredients is mixed in to form a herbal dough. This dough is then cut into tiny pieces by a machine, and a small amount of excipients are added for a smoother and a more consistent exterior. The products are then made as pills.
Honey or water pills made from ground raw herbs are also a popular format in China, and they tend to be larger and are slightly to significantly softer than teapills. Honey pills and water pills have been made since ancient times by combining several dried herbs and other ingredients, which are grounded into powder, mixed with a binder and traditionally formed into pills by hand. Modern honey or water pills are formed into pills by machine. The binder is traditionally honey for honey pills. For water pills the binder may simply be water, or may include another binder, such as molasses. Modern manufacturers still produce many patent formulas as honey or water pills, such as Wuji Baifeng Wan, a popular honey pill formula to "nourish qi and blood", to strengthen the body.
Also common are external-use products: plasters (also gao ), tinctures, and liniments. Some medicated liquors are for both internal and external use.
Newer forms As mentioned in the "History" section, the original form of Chinese patent medicine is the extract granule. A granule can be reconstituted with water much like an instant tea. Granules are made by drying a decoction and serve as a more convenient form the decoction, with no prolonged boiling needed. Sugar is often added as excipient and sweetener. – This is an arbitrarily-chosen CPM in granule format. This formula supposedly treats hepatitis B. Similarly, a powder derived from drying a decoction can be pressed into a tablet or packaged into a capsule.For examples, see chapters and , which documents the manufacturing process of a tablet and a capsule both based on the same TCM combination. Volume I of the 2020 ChP (Chinese edition), pp 459, 460.
Another form that only became common with modern packaging is the liquid. The liquid can be water-based similar to the tea used to make the teapill, or be an alcohol-based extract of herbs. , a medication supposedly for heat illness, is an alcohol-based liquid. It has also been packaged into a softgel. – This is a PRC Pharmacopoeia monograph. It specifies the proportion of ingredients and the process of manufacture.
Forms for use in combination
Some forms of Chinese patent medicine is not intended for direct use by the patient, but are extracts for mixing with other herbs or extracts to produce a customized formula. When each boiled-extract corresponds to one single herb, they can be mixed together according to a traditional Chinese medicine prescription, substituting the herbs to be boiled with a corresponding amount of the extract. The main example of this class is "granules for use in combination" () – granules made from drying a decoction. These forms give the no-boil convenience of CPMs to TCM practitioners who provide customized prescriptions for each patient.
Fixed-formula Chinese patent medicine have also made use of similar approaches to simplify manufacture and to use more modern extraction methods. For example, volume 1 of the Chinese Pharmacopoeia (which deals with TCM and CPM) includes such ingredients as a rhubarb extract (extracted using hot water-ethanol mixture), a ginkgo leaf extract (extracted using a dilute water solution of ethanol), and a total ginsenoside [from] ginseng root (extracted through column chromatography). Vol 1 2020 edition. Chapters , , . Pages 413, 434, 409.
Injections A phenomenon mostly confined to China is the use of TCM-derived fluids for injection. Originally an attempt at rationing herb use during the Second Sino-Japanese War, numerous TCM-derived injections have been formulated and used in China. By the 1980s, as many as 1400 different injections are on the market. In the 1980s, a stronger regulatory framework was established for these injections. Reports of severe adverse effects have encouraged further improvements in regulation, with safety re-evalulation started in 2009. Another re-evaluation, this time combining safety and effectiveness, was started in 2017. In 2022, Lian Bi Zhi injection became the first TCM injection to be delisted due to failing postmarket re-evaluation.
The most common adverse effect events for TCM injections are fevers, allergy, and allergy-like symptoms (e.g. mediated through mast cell or complement system), with the last being the most common. One particularly serious offender, Houttuynia cordata injection, has caused 22 deaths through anaphylactic shock in a span of 2 years. Its package insert has since been modified to remove intravenous use as an accepted route, leaving intramuscular only.
National regulatory infrastructure now exists for collecting reports of adverse effects. The proportion of injection-related adverse events in all TCM-related adverse events is trending down since 2017.
Regulation Like other patent medicines, they are not necessarily patented in the traditional sense of the word. Typically no-one has exclusive rights to the formula. The term patent medicine is borrowed to refer to their often unclear effectiveness. Unlike Western "patent medicine" of old, these products have a fixed proportion of ingredients, as they are put under a modern regulatory framework.
China In China, all Chinese patent medicines of the same name have the same proportions of ingredients, and are manufactured in accordance with the PRC Pharmacopoeia's monograph on that particular formula, which is mandated by Chinese law. Each monograph details the exact herbal ingredients that make up the patent formula, usually accompanied by the specific tests that should be used for correct herb identification, such as thin layer chromatography (TLC) or high performance liquid chromatography (HPLC), the percentage of each ingredient, and specific cautions and contraindications. The monograph also details the manufacturing methods that must be followed, how to process and cook the herbs, often including specific requirements for finished product testing including authenticating and assessing the potency of the formula with active ingredient markers where known, as well as testing for dissolution time and content uniformity. All good manufacturing practice (GMP) certified factories must also test for heavy metal levels and microbials for all patent medicines they produce.State Pharmacopoeia Commission of the PRC (2005). "Pharmacopoeia of The People's Republic of China (Volume I)". Chemical Industry Press.
However, many patent medications do not list all ingredients, presumably to protect the secrecy of the formula. An example of this is Yunnan Baiyao, a popular formula used to stop bleeding, whose ingredients have never been revealed. This is an acceptable practice in China, where no other protection exists to protect family or "secret" Chinese herbal formulas. The state has access to the Yunnan Baiyao formula for regulatory purposes.
Taiwan
Japan Traditional Chinese medicine entered Japan in the 7th century and has been developing on its own as Kampō. As mentioned earlier, the practice of producing ready-to-use granules originated in Japan. The Ministry of Health, Labour and Welfare manages a Kampo list which contains specific approved forms of mixed and single-herb herbal medicine. In October 2000, a nationwide study reported that 72% of registered physicians prescribe Kampō medicines.
Other countries In western countries, there is considerable variation of ingredients and in the proportions of ingredients in products sharing the same name. This is because the Chinese government allows foreign companies to apply for modifications of patent formulas to be sold outside of China. For example, Hebei brand Lĭfèi Wán () contain Kadsura vine () and Morus alba leaf (), whereas Plum Flower brand Lĭfèi Piàn () contains Schisandra chinensis fruit () and Gecko flesh () instead. Another example is Qīng Qì Huà Tán Wán (). The Lanzou brand uses Mandarin orange peel (). The Lanzhou Foci ()/Min Shan () brand and the Plum Flower brand do not, but use ginger rhizome ().
For comparison, the monograph for Qīng Qì Huà Tán Wán in the 2020 edition of the PRC Pharmacopoeia uses and no ginger. The 2020 edition of the PRC Pharmacopoeia does not have a monograph for Lĭfèi Wán or Lĭfèi Piàn, though it has monographs with other preparations with Lĭfèi in the name.
Examples
Classic formulas
Chinese classic herbal formulas form the basis of Chinese patent medicine. These are the basic herbal formulas that all students of traditional Chinese medicine learn. Many of these formulas are quite old. For example, was developed by Qián Yǐ () (c. 1032–1113 CE). It was published in the in 1119 by Qian Yi's student. Although Liu Wei Di Huang Wan can be prepared as a raw herb decoction (or herbal tea), it was originally created to be made into honey pills. The last word in Liu Wei Di Huang Wan, "Wan" () means "pill".Chinese Medicine Guide, 3 September 2023