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Rasashastra is a science which deals with the usage of Metals, Minerals, Gem stones, Poisonous substances to treat diseases and convert the lower metals into higher one. This science came into existence during 7th-8thcentury.
It has been accepted as part of Ayurveda. Before the metals and minerals are used for therapeutic benefit, it becomes necessary that they are used in its pure form to eliminate any physical, chemical or toxic impurity, to change its physical or chemical form and to potentiate properly.
The word ‘Shodhana’ in Ayurveda denotes Purification. Hence Shodhana can refer to the purification of the body during the treatment or the substance and herb before the preparation of medicine. There is mention of the context of Shodhana in the ancient text of CharakaSamhita but the procedure related to shodhana of minerals etc are described in various texts related to Rasashastra. In the context of Rasashastra the word ‘Shodhana’ refers to the purification of the metals, minerals or the toxic substances which are used for therapeutic benefit.
uddhiṣṭerauṣadhai: sārdhaṃ kriyate peṣaṇādikaṃ |
malavicchittaye yattu śodhanaṃ tadihocyate ||
Purpose of Shodhana
The substance is subjected to shodhana before it is used further for therapeutic use. The purpose is manifold-
- To purify the substance from any physical, chemical and geological impurity.
- To reduce or completely remove any toxicological impurity from the substance.
- To alter the physical and chemical nature of the substance.
- To reduce the particle size of the substance for better bioavailability.
- To enhance the therapeutic quality of the substance by the process of shodhana.
- To render the substance for further therapeutic use.
Samanya and Vishesha Shodhana
Books related to Rasashastra have described various methods which can be used for the process of shodhana and they can be broadly grouped into two-
- Samanya shodhan- common procedure
- Vishesha shodhan – special procedure
Samanyashodhana refers to the procedures carried over a group of metals, minerals or precious gems. In this type the purification method remains the same though the metal or mineral may vary.
Visheshashodhanarefers to the procedure where special method is carried for purification of each individual metal, mineral or gem.
Various techniques and different liquid media are used for the process of shodhana. The liquid media may vary from water to decoction of plant, fresh juice, cow milk, cow urine, or oil, which have acidic or alkaline property. The selection of the liquid media depends upon the substance which is to be purified and the method adopted for purification.
Different methods of Shodhana
Bhavana and Mardana-This is the most common method of shodhana. The substance is taken in a khalvayantra and triturated with a specific mentioned liquid for a period of time. The procedure helps in the particle reduction and better absorption capacity of the active principles.Eg.Gairikashodhana
Swedana- In this procedure the substance is covered with a cloth, tied and dipped in a liquid media and heated for a period of time so that the external impurity present in the substance is separated and the substance becomes soft and brittle.Eg.Shankashodhana
Dhalana-The procedure where the substance is completely melted and poured into a liquid is called as Dhalana. Eg.Vangashodhana
Patana- In this procedure the substance is distilled by giving a quantum of heat to separate two or more substances mixed with each other. Eg.ParadaUrdwapatana
Nirjalikarana: The chosen substance is fried in a flat mud plate over fire to remove the water content from the substance. Eg.TankanaNirjalikarana
Bharjana: The substance is fried using ghee or without adding any substance in a pan to reduce the strength of the substance. Eg.Hingubharjana
Gharshana- This procedure enables the substance to be softened or rubbed against another hard object like piece of stone or brick. Eg.Bhallatakashodhana
Nirvapa: The procedure where the substance is heated to red hot and dipped into a liquid for softening and gaining the brittleness. Eg.Abrakashodhana
Avapa: The procedure where the hot liquid is poured over the substance to soften it and remove the external impurities present.
Prutakikarana: It is the manual separation of any physical impurities like small stone particles, dried leaf etc from the substance. Eg. In Guggulushodhana
Prakshalana: The substance is washed with water to clean which helps in the removal of physical impurity like sand particles, small leaf particle etc. Eg. In Kampillakashodhana
Galana: The procedure where the substance is filtered using a sieve to separate the physical impurity.
Nimajanna: The procedure where the substance is dipped in a liquid to reduce its chemical strength. Eg.Vatsanabha is dipped in cow’s urine.
Soshana:The substance is dried under sunlight to dry to enable the moisture content to be evaporated and increase the shelf life.
The above are some of the methods told in various texts of Ayurveda and Rasashastra for shodhana. Some methods are told under different names for the similar procedure.
Media used for shodhana
Different liquid media are used for the purpose of shodhana and they have their origin from either animal or plant source. Some liquid media are prepared from the mineral substance.
The liquid media used for the shodhana have different Rasa i.e Amla, Tikta, Kashaya. The liquid used can be either a decoction, urine of selective animals, oils, sour liquids like buttermilk or ‘kanjika’ etc. The selection of the proper liquid media helps in softening and removing the impurity from the substance, reducing the particle size of the purified substance, physical and chemical transformation of some substances.
Research works carried to prove the efficacy and necessity of shodhana:
By the above different methods used for shodhana it becomes clear that metals, minerals and some substances are not fit for therapeutic use in its original form and hence need modification in its physical and chemical form. The different methods used for shodhana gives a method and technique to alter the substance and redeem it fit for consumption in its therapeutic dosage form. Shodhana is a samskara which is a prerequisite for all the Rasa dravyas to be used effectively for ‘Deha vada’ i. e therapeutic use.