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→Pharmacokinetic of Drug
==== Pharmacokinetic of Drug ====
==== Pharmacokinetic of Drug ====
Drugs (used for emesis and purgation) which are ''ushna'' (hot), ''tikshna'' (sharp), ''sukshma'' (subtle), ''vyavayi'' (those pervading the entire body before getting digested) and ''vikasi'' (those causing looseness of joints), by virtue of their own potency, reach the heart and circulate through the vessels. Because of their ''agneya'' nature (predominance of ''agni mahabhuta'', or fire element), they liquefy the compact form of (adhered) ''doshas'' (morbid material), and because of their sharpness (''tikshna'' attribute) they separate the adhered ''doshas'' located in the gross and subtle channels of the entire body. Like honey kept in the pot smeared with fat, the morbid material, after separation, moves floating without adhesion in the body which has been oleated (by the administration of oleation therapy). Because of its nature to move through subtle channels and to flow (towards the gastro-intestinal tract), this morbid material reaches the stomach, and gets propelled by ''udana vayu''. Because of the predominance of agni and vayu mahabhutas in these (emetic) drugs, and because of their specific action (prabhavajanya) to move upwards, the morbid material gets expelled through the upward tract (mouth). On the other hand, purgative drugs, because of the predominance of prithvi and jala mahabhutas, and because of their specific action, (prabhavajanya) move downwards to expel the morbid material through the downward tract (anus). Combination of both these attributes result in the expulsion of the morbid material through both the upward and downward tracts.
Drugs (used for emesis and purgation) which are ''ushna'' (hot), ''tikshna'' (sharp), ''sukshma'' (subtle), ''vyavayi'' (those pervading the entire body before getting digested) and ''vikasi'' (those causing looseness of joints), by virtue of their own potency, reach the heart and circulate through the vessels. Because of their ''agneya'' nature (predominance of ''agni mahabhuta'', or fire element), they liquefy the compact form of (adhered) ''doshas'' (morbid material), and because of their sharpness (''tikshna'' attribute) they separate the adhered ''doshas'' located in the gross and subtle channels of the entire body. Like honey kept in the pot smeared with fat, the morbid material, after separation, moves floating without adhesion in the body which has been oleated (by the administration of oleation therapy). Because of its nature to move through subtle channels and to flow (towards the gastro-intestinal tract), this morbid material reaches the stomach, and gets propelled by ''udana vayu''. Because of the predominance of ''agni'' and ''vayu mahabhutas'' in these (emetic) drugs, and because of their specific action (''prabhavajanya'') to move upwards, the morbid material gets expelled through the upward tract (mouth). On the other hand, purgative drugs, because of the predominance of ''prithvi'' and ''jala mahabhutas'', and because of their specific action, (''prabhavajanya'') move downwards to expel the morbid material through the downward tract (anus). Combination of both these attributes result in the expulsion of the morbid material through both the upward and downward tracts.
==== Similarities/ Dissimilarities of ''virya'' ====
In a study the variations in the phytoconstituents of Ashwagandha root was evaluated according to lunar cycles with regard to greeshma and sisira ritu (summer and late winter season). In this study, total phenolic, flavonide and carbohydrate content of Ashwagandha Root were found more in pournima (full moon day) samples. GAP (greeshma rithu) samples showed maximum differentiation from rest of the samples with regards to TCA, TCW, TFW, MEx, WEX, pH etc. parameters. The Grīṣṃa Jyeṣṭha Paurṇimā (GJP) and Āṣāḍha Paurṇimā (GAP) samples were found to be superior than amāvāsyā (new moon day) samples with regard to functional groups and withanoloid content respectively (Ref. 2016 Ancient Science of Life) . Such type of studies validate the concept of seasonal collection of drug delineated in ayurvedic classics like Charkasamhita and Sushruthasamhita.
Sometimes, the drugs of secondary nature (mixed with main drug) have antagonistic property. Even then they do not contradict the effects of the principal drug. If these drugs of secondary nature are similar in potency as that of the principal drugs, then the recipe becomes all the more effective therapeutically. Trituration, boiling etc. are considered ''samskaras'' which bring in chemical changes in the chemical structure of the drug which results in potentiation or neutralization of the drug activity.
==== Modification of drug activity ====
Ingredients of a recipe should be impregnated with the juice or decoction of other ingredients having identical potency. By virtue of appropriate ''samyoga'' (addition of ingredients), ''vishlesha'' (elimination of ingredients), ''kala'' (appropriate time of administration) and ''samskara'' (processing) even a small quantity of a drug may produce more powerful effects, and otherwise even a recipe in large quantity may produce very mild effects.
==== Weight and measures ====
Two traditions for ''mana'' (weight and measures) are mentioned in Kalpa Sthana, namely, ''Kalinga'' (part of present Orissa) and ''Magadha'' (part of present Bihar). Charaka opines that Magadha is better than former. Chakrapani considers this statement as unauthentic. It is also suggested that when weight of ingredients in a recipe is not specified, then all the ingredients are to be taken in equal quantity.
==== ''Snehapaka'' (Dosage form) ====
Charaka Samhita does not specify the liquid medium to be used in formulation of the medications. However, the use of certain liquids has been known through practice and other sources. In the process of ''snehakalpana'', for example, water has to be used invariably. ''Snehapaka'' (preparation of medicated oil or ghee) is categorized into three types i.e. ''mridupaka'' (mild boiling), ''madhayamapaka'' (moderate boiling) and ''kharapaka'' (full boiling). ''Sneha'' processed by ''kharapaka'' is indicated for massage purpose, ''mridupaka sneha'' is recommended to be used for ''nasya'' (inhalation) and moderately processed oil or ghee for internal use including for ''basti karma''.
==== Purification of drugs ====
To reduce the toxicity (''vikasi guna'') of ''Danti'' and ''Dravanti'', Charaka evolved a process using ''Pippali'' and honey paste which is to be besmeared over the roots and once again to be smeared with mud and fomented with steam after drying up in sun. Chakrapani observes that heat of fire and sunrays makes the root free from adverse effects. This could be quoted as a best example of purification process employed for the removal of toxicity - a novel concept mentioned by Charaka. In the medieval ages, ''Rasashastra'' texts adopted several purificatory procedures for various herbal and metallic drugs.
=== Relevance of the concepts of Kalpa Sthana in the current clinical practices ===
''Vamana karma'' (emesis) and ''virechana karma'' (purgation) are mandatory before performing ''basti karma'' (enema), in order to promote health (i.e., for the patient to gain mass). Keeping this in view, the details about drugs employed in ''vamana'' and ''virechana karma'' are described in this section and the details about ''basti karma'' in the subsequent section, [[Siddhi Sthana]].
For ''vamana karma'', ''Madanaphala'' is the main drug employed in the current clinical practice. But the rest of five drugs (i.e., ''Jimutaka'', ''Ikshvaku'', ''Dhamargava'', ''Vatsaka'', and ''Kritavedhana'') are not being prescribed. Charaka suggested the period of collection and procedure for extracting seed from the ''Madanaphala''. These procedures are not being followed currently.
In the purgative therapy the drug ''Trivrita'' is prescribed currently in the various dosage forms and ''Aragwadha'' and ''Danti'' are infrequently prescribed. Charaka suggested a procedure for extracting the pulp from the fruit of ''Aragwada''. He also described a process to reduce ''vikasi guna'' (causes looseness of tissues) of ''Danti'' root. Both these procedures are not in vogue. Sushruta suggested ''Triphala'' (3 Fruits namely ''Haritaki'', ''Vibitaka'', and ''Amalaki'') and ''Eranda Taila'' (Castor oil) as purgatives and are prescribed in the current clinical practice.
''Tilvaka'', ''Saptala'', ''Sankhini'', and ''Dravanti'' are the purgative drugs suggested by Charaka which are controversial and not being preferred in current practice.
The procedures described by Charaka with regard to ''vamana'' and ''virechana karma'' are being followed religiously by Ayurvedic physicians of current times.
Ayurvedic classics have advocated to collect the medicinal plants according to part used and seasons in order to get desired pharmacological action and therapeutic benefits. Sushruta, Charaka and other acharyas advocate the collection of various parts of medicinal plants in different seasons. The logic behind such recommendations has been validated by recent modern scientific research.
In a study the variations in the phytoconstituents of ''Ashwagandha'' root was evaluated according to lunar cycles with regard to ''grishma'' and ''shishira ritu'' (summer and late winter season). In this study, total phenolic, flavonide and carbohydrate content of ''Ashwagandha'' root were found more in ''poornima'' (full moon day) samples. GAP (''Grishma Ashadha Poornima'', or the full moon night occurring in the ''Grishma-Ashadha'' season) samples showed maximum differentiation from rest of the samples with regards to TCA, TCW, TFW, MEx, WEX, pH etc. parameters. The ''Grishma-Jyeshtha Poornima'' (GJP) and GAP samples were found to be superior than ''Amavasya'' (new moon day) samples with regard to functional groups and with anoloid content respectively (Ref. 2016 Ancient Science of Life) . Such type of studies validate the concept of seasonal collection of drug delineated in Ayurveda classics like [[Charaka Samhita]] and [[Sushruta Samhita]].