Shodhana means cleansing.The process through which you can remove the doshas (impurities of dravya (medicinal substance)is called shodhana.
The dravya on which the process of shodhana done is called as Shudhidravya or shodhya dravya.And the substance with which it is treated for purification called as Shodhana dravya.

Purpose of Shodhana Karma-
Shodhan karma not only removes the unwanted materials from drugs but controls toxic effects in dravyas.
Shodhana process enhances the efficacy of drugs.
It reduces the intensity of astringent taste
Sharpness (Tikshantva )of dravya can be reduced by this process of shodhana
Reduces hardness of dravya
Removes the dust particles and make it insect free.

Types Of Shodhana-
Shodhana karma divided in to two types mainly.

1.Samanya shodhana- Samanya shodhana process is applicable to dravyas which comes in to same caterories like Maharasa,Uparasa,Ratna. he drugs belongs to same category,have similar types of impurities so with the help of Samanya shodhana e can removes the general impurities from Dravya.
Ex-Samanya shodhan of dhatu like swarna(gold),rajat(silver),loha (iron) etc

2. Vishesh Shodhana- The word vishesh means specific.The dravyas which contain high concentrated chemicals ca be removed out by this process.Each drugs have their specific and different types of impurities so for their removal vishesh shodhana is required.

 Sr.No  Procedures  Meaning  Pharmaceutical action Example
 1  Swedana  Vaporizations of raw drugs in certain liquid material  Its results in brittleness of dravya  Hartal in Kushmand swarasa
 2  Mardana  Trachuration with swarasa,kashaya,godugdha,gomutra  The drugs particle size becomes senergistic additives,so it acts as agonist  Jambir swaras used to triturate tamra patra
 3  Murchana  Trachuration up to fine disintegration  Reduction in particle size  Parad by Adraka swarasa
 4  Patana  Extracted is collected by giving the heat to substance till its vaporization  Separation of adulterants causes purification of medicines  Extraction of parad from hingu
 5  Avap/Dhalan  First raw solid drugs can be melt and then dipped in to cold liuid  Reduces brittleness and separate adulterants from dravyas  Gandhaka in godugdha
 6  Nirvap  Heating solid drugs and then dipped in to cold liquid  Reduces brittleness  Abhraka in triphala kwath
 7  Galan  Filtration  Seperates the unwanted and heterogenous substances from dravya  Any filtrate after filtration
 8  Prakshalana  Cleaning of dravya by proper washing  Removes the dust and insects  Balamool roots washing with water
 9  Nimajjanam  Raw drugs should be dipped in to certain liquid for some period of time  Chemical changes from higher concentration to lower concentration takes place  Vatsnabha in godugdha ,gomutra
 10  Bharjana  To fry  Unwanted part evaporates  Tankana
 11  Sanyog  Adding of another drug  Minimizes the toxicity  Tankana in vastanabha
 12  Vibhag  To separate the unwanted part  Minimizes the tikshantva  Rasankur in rason
 13  Pachana  Dravya should be immersed in shodhana material and keeping on fire  Increases softness and reduces stickiness  Guggulu in godugdha/Triphala kwath
 14  Shoshana  Drying in sunlights/moonlight  Results in absortion of dravya at tissue level  Apamarga bija
 15 Sinchana  To spread the liquid on hotrat drugs  Results in absortion of dravya at tissue level  Apamarga bija
 16  Sthapana  To keep the dravya in stable condition  Kalgunvridhi (increases quality of drugs)  Puran ghrita,puran guda
 17  To peel  Skin removing  Separates the unwanted part  Ginger
18 To dehusk Removing of husk from grains Seperates unwanted parts shalidhanya