The Art of Drug compounding in Traditional Thai Medicine
Within the past decade, there has been an in global awareness of environmental issues including the proper usage and preservation of natural resources. Thailand, in an effort to become self-reliant, has strived to fully utilize and protect the existing natural resources including medicinal plants. In solving the country’s health problems, the government has resorted to the use of medicinal plants in order to provide basic health care for the people. In spite of the fact that much of the research carried out on Thai medicinal plant has, in the past, been directed towards the isolation of active compounds for use as modern drugs, it is recognized that appropriate modification and development of indigenous drugs are of equal importance.
The intrinsic principles of traditional Thai medicine are propounded on the knowledge of
1. Drug matters. This concerns the basic knowledge of each drug ingredient which may be derived from plant, animal or mineral. Traditional practitioners must be knowledgeable on the names, description, colour, odour and tasted of each drug.
2. Drug attributes. In Thai medicine, drugs are divided into groups according to their pharmacological actions. The tastes ascribed to the formulated drugs are believed to be correlated to their ability to cure certain ailments. For instance, drugs with a cooling taste are said to cure ailments caused by the restoration of the wind element. Individual drugs are recognized as possessing astringent, sweet, bitter, acrid, nutty, salty or sour tastes.
3. Drug grouping. To facilitate drug prescription in traditional Thai medicine where a recipe may consist of 30-40 ingredients, a number of drug ingredients are grouped together. These may be ingredients with similar nature or attributes or they may be different drugs grouped together to form specific entities. Each of these drug groups may consist of two to nine ingredients. An example of these entities is “the two licorices” comprising Thai licorice (Albizia myriophylla) and Spanish licorice (Glycyrrhiza glabra).
4. Drug dispensing or compounding. In traditional Thai medicine, a drug refers to two or more ingredients mixed together into an appropriate dosage form. The ingredients contained in each recipe may be classified into three main categories, namely the principal drug(s) , The adjuvant (s) and the flavouring agents. In general, twenty-five dosage forms are recognized. These include the more common preparations, such as pills, decoctions, alcoholic macerates, snuffs, poultices and suppositories. In addition to these traditional dosage forms, the Ministry of Public Health has permitted two more modern dosage forms for traditional drugs, i.e. tablets and capsules. Preservatives are also allowed to be used in traditional drug formulation.
Beside the main principles as outlined above, other factors also have to be
taken into consideration. These are
1. Specific Knowledge of drug ingredients. Since more than one drug plant may possess identical common or local names, traditional practitioners must be able to identify the correct species and to differentiate between useful species and poisonous ones. The knowledge on the part or parts of medicinal plants to be used is also essential. Other pertinent information includes the forms in which the drug ingredients are required. Some ingredients are best used fresh while other are used in the dried form. Certain ingredients may need to be detoxified prior to use.
2. Doses. The appropriate amount of each ingredient is usually measured out using the old system of measurements. An example of traditional Thai system of measurement for weight is given below.
1 chang (1.200 g) = 20 tum-lueng
1 tum-lueng (60 g) = 4 baht
1 baht (15g ) = 4 salueng
1 salueng (3.75 g) = 2 feung
1 feung (1.875 g) = 4 pai
1 pai (0468g) = 2 utt
Traditional systems for measuring lengths and capacities also exist.
3. Vehicles. These are liquids used in drug formulation in order to dissolve or to extract active constituents from drug ingredients. In many cased, they may act to potentiate the action of the principal drug. Vehicles used in traditional drug formulation include water, spirit and lime water, for instance. The potency of the elixir may depend on the choice of vehicle used.
4. Methods of preparation. Of the 25 dosage forms previously mentioned, in practice only four or five are in common use and these are briefly described below.
PREPARATION OF DRUG INGERDIENTS
All ingredients must first be washed and then cut into small pieces if they are to be used fresh. If dried ingredients are required, fresh. If dried ingredients are required, fresh ingredients are sliced thinly and sun dried.
Flued Extracts
Both fresh and dried ingredients may be prepared in the above explanation. The method is suitable for ingredients which are water soluble but may be unappetizing in their crude forms. To prepare an extract, the plant materials are placed into a utensil which may be a clay, an enameled or stainless steep pot. Water is added as stipulated in the recipe or until it just covers the ingredients. The mixture is then boiled for 2-30 minutes depending on the types of ingredients used.
Infusion
A somewhat simpler version of the above procedure, the method entails the addition of boiling water onto finely shredded ingredients contained in a small cup or glass with a lid. The mixture is set aside to brew for 3-5 minutes, after which the clear supernatant is decanted.
Alcoholic Macerates
This method is mostly used for extracting water-insoluble constituents from dried drug ingredients. Air-dried drugs are weighed, wrapped in a piece of muslin and then placed into a glass jar with a tightly fitted lid. Sufficient quantity of spirite (28-40 degree proof) is then added to just cover the ingredients. With daily stirring, the maceration process is usually allowed to proceed for a period of 1-5 weeks.
Pills
To prepare pills, Binding agents such as honey as honed or syrup are used. Dried and finely powdered ingredients are placed into a bowl and a small amount of honey is gradually added. This mixture is then kneaded into a large ball. The mixture may be shaped into small round balls by hand or with aid of a special tool. The finished pills are then sun dried for 1-2 days. The pills produced in this way may be stored in closed jars for up to one month.
As outlined above, the techniques of drug compounding in traditional Thai medicine are, in most cases, Kept simple with minimum requirement for sophisticated equipment, so that they could be practiced at household and community levels. With the advancement of today’s technology, however, the methods of indigenous drug production could be vastly improved to make the drugs more effective, safer and more acceptable to the modern generation.
TAMATRND
Scientific name: Tamarindus indica Linn.
Family: GEGUMINOSAE
Vernacular name: Ma-Khaam
The pulp is used as a laxative in traditional Thai medicine while the kernels from roasted ripe seeds are used as an anthelmintic for threadworms in children. The pulp contains 12-15 percent of organic acids including tartaric, citric and lactic acids.
PLAUNOI
Scientific name: Croton sublyratus Kurz
Family: EUPHORBIACEAE
Vernacular name: Plaunoi
ASIATIC PENNYWORT
Scientific name: Centella asiatica Urban
Family: UMBELLIFERAE
Vernacular name: Bua-bok
PLAI
Scientific name: Zingiber cassumunar Foxb.
Family: ZINGIBERACEAE
Vernacular name: Plai
The pressed juice from pounded fresh rhizomes has long been used to relieve sprains. The powder derived from the dried rhizomes is used in traditional medicine as an anti-asthmatic agent.
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