PROBABLE MODE OF ACTION- AYURVEDIC
VIEW
In Ayurvedic
classics, Acharyas have tried to explain actions of Vasti with suitable
analogism(Ch.Si.1/31)
As
tree irrigated in its root level attains nourishment for whole tree, In the
same way, Vasti drugs given through Guda {Rich in blood vessels, lymphatic
& nerves} Nourishes all the limbs & organs of the body. By the above
mentioned reference, a collation of information about Guda Sharira (structure
of Anus), its relations, its physiology etc. gives compendious information about
it.
Guda
(Anus) is one of the Pranayatana, where all twelve Prana dwell predominantly.
Guda (Anus) is a Mamsa marma of Sadyapranahara type. Being a Marma it has roots
of all four types of Sira embedded in it viz. Vatavaha, Pittavaha, Kaphavaha
and Shonitavaha..
Due
to its Sadyapranahara nature, Guda (Anus) is highly sensitive. Even a mild
stimulation to it, say, by Vasti drugs and procedure may sensitize the whole
body by vigorous action of Vayu through all the Siras present in the body. This
physiology confirms immediate and all pervasive action of Vasti drugs even
though the Vasti lies in Pakvashaya.
Relations
of Guda (Anus):
Apana
Vayu- Anus is the seat of Apana Vayu
Prana
Vayu- Being Sadyapranahara Marma
Vyana Vayu - Vyana is all-pervasive
Samana Vayu - It moves all over the Koshtha.
Pachaka
Pitta - Helps
in digestion
Sira, Snayu, Sandhi, Asthi & Mamsa
Sannipata- as it is a Marma
Kala- Maladhara, Asthidhara
and Majjadhara.
Dhatu- Rasa, Rakta,
Mamsa, Meda, Majja & Shukra.
From
the above-sited relevance it may be said that, Vasti influences whole body.
However, it acts mainly on the structures related to Guda (Anus). If Apana is
controlled in its own abode other four Vayu can be bridled automatically.
Vasti
drugs in Pakvashaya acts on whole body in a same way that of sun, which though
placed in the sky, causes evaporation of water on the earth. The Virya
(potency) of Vasti dravya is first taken up by Apana Vayu, i.e. it acts or
influences the Guna of Apana Vayu with which it comes in contact first.
Consequently the Samana Vayu is also affected followed by Vyana, Prana and
Udana. By the Guna of Vasti dravya, the vitiated Vayu regain their normal state
and supports the body. They also bring vitiated Pitta and Kapha in their normal
state, and the five types of Vayu nourish their respective Sharira-Bhuta Guna.
The Virya (potency) of dravya (substance) are propagated by the Vyana in
Tiryaka or lateral direction, by the Apana in downward direction and in upward
direction by Prana, just as water pipes carry water to the different parts of
the field similarly the “Harini” (Channels) carry the Gunas of the Vasti dravya
to every part the body, hence a Vasti which is appropriate will with the help
of Vata, Pitta and Kapha through the Siras will spread in all over the body and
cures even the most difficult disease.(A.S.Ka.5/24)
Pakvashaya
is the place where Poshakamsha (nutritive substances) originates and supplies
the nutrition to all Vayu. As Vasti is introduced in its Udbhavasthana, it has
capacity to control all the five Vayu. However it acts more on Samana and Apana
because it has direct contact with their places.
PROBABLE
MODE OF ACTION- MODERN VIEW
A.
Absorption
in systemic circulation
B.
Colon
cleansing
C.
Gut
brain theory
D.
Influence
on Bacterial Flora
A)
ABSORPTION
IN SYSTEMIC CIRCULATION
Vasti
may be absorbed by: diffusion, filtration, osmosis or by adsorption depending
upon substance used in it.
Though small intestine is
supposed to be an important organ for absorption of food & drugs colonic
administration of drug has a specific importance. Thus colon targeted drug
delivery is gaining popularity. It is a concept that is being used in Ayurveda in the form of Vasti.
“Colon
Targeted Drug delivery, an old concept in new perspectives”
Why
colon targeted drug delivery needed?
v Targeted drug delivery to the
colon would ensure direct treatment at the disease site, lower dosing and fewer
systemic side effects.
v Colon-specific drug delivery
system is considered to be beneficial in the treatment of colon diseases.
v The colon is a site where both
local or systemic drug delivery could be achieved, topical treatment of
inflammatory bowel disease, e.g. ulcerative colitis or Crohn’s disease.
v A number of others serious
diseases of the colon, e.g. colorectal cancer, might also be capable of being
treated more effectively if drugs were targeted to the colon.
v Formulations for colonic delivery
are also suitable for delivery of drugs
which are polar and/or susceptible to chemical and enzymatic degradation in
the upper GI tract, highly affected by hepatic metabolism.
v COLON ANATOMY
The GI tract is divided into
stomach, small intestine and large intestine. The large intestine extending
from the ileo-caecal junction to the anus is divided in to three main parts.
These are the colon, the rectum and anal canal.
v The
entire colon is about 5 feet (150 cm) long, and is divided in to five major
segments. Peritoneal folds called as mesentery which is supported by ascending
and descending colon.
v The
right colon consists of the caecum, ascending colon, hepatic flexure and the
right half of the transverse colon. The left colon contain the left half of the
transverse colon, descending colon, spleenic flexure and sigmoid.
Fig
no. 1.2: Showing Anatomy of Large intestine and intestinal wall
v The
rectum is the last anatomic segment before the anus.
v The
major function of the colon is the creation of suitable environment for the
growth of colonic micro-organisms, storage reservoir of faecal contents,
expulsion of the contents of the colon at an appropriate time and absorption of
potassium and water from the lumen.
v The
absorptive capacity is very high, each about 2000ml of fluid enters the colon
through the ileo-caecal valve from which more than 90% of the fluid is
absorbed.
v On
average, it has been estimated that colon contains only about 220 gm of wet
material equivalent to just 35 gm of dry matter. The majority of this dry
matter is bacteria. The colon tissue contains the villi, lymph, muscle, nerves,
and vessels.
Drug absorption in the colon:
Drugs are absorbed passively by
either paracellular or transcellular route. Transcellular absorption involves
the passage of drugs through cells and this is the route most lipophilic drugs
takes, where paracellular absorption involves the transport of drug through the
tight junction between cells and is the route most hydrophilic drug takes. The
colon may not be the best site for drug absorption since the colonic mucosa
lacks well defined villi as found in the small intestine. The slower rate if
transit in colon lets the drug stay in contact mucosa for a longer period than
in small intestine which compensates much lower surface area.
Standing gradient osmosis:
Water absorption at the colon
typically proceeds against a transmucosal osmotic pressure gradient. The standing gradient osmosis is a
term used to describe the re-absorption of water against the osmotic gradient
in the intestines. This hypertonic fluid creates an osmotic pressure that
drives water into the lateral intercellular spaces by osmosis via tight
junctions and adjacent cells, which then in turn moves across the basement
membrane and into the capillaries.
“Why Vasti may prove better than oral
drugs for colon targeted drug delivery?”
As a site for drug delivery, the
colon offers a near neutral pH, reduced digestive enzymatic activity, a long
transit time and increased responsiveness to absorption enhancers; however, the
targeting of drugs to the colon is very complicated. Due to its location in the
distal part of the alimentary canal, the colon is particularly difficult to
access.
In addition to that the wide
range of pH values and different enzymes present throughout the
gastrointestinal tract, through which the dosage form has to travel before
reaching the target site, further complicate the reliability and delivery
efficiency. However Vasti has-
ร
Direct
access to colon.
ร
Quick
action as transit time is not an obstructive factor.
ร
No
enzymatic degradation as in case of oral drugs targeting colon while travelling
from upper G.I. tract.
Successful delivery through this
site also requires the drug to be in solution form before it arrives in the
colon or, alternatively, it should dissolve in the luminal fluids of the colon,
but this can be a limiting factor for poorly soluble drugs as the fluid content
in the colon is much lower and it is more viscous than in the upper part of the
GI tract.
Vasti itself is a thick liquid
consistency fluid providing enough solution media for drug absorption.
In addition, the stability of the
drug is also a concern and must be taken into consideration while designing the
delivery system. The drug may potentially bind in a nonspecific way to dietary
residues, intestinal secretions, mucus or faecal matter.
The volume of Vasti is considerably large that
ensures required dose delivery & the protocol for administration is well
designed by Acharyas to avoid faecal matter or dietary residue binding by stating do’s & don’ts for Vasti administration.
The resident microflora could
also affect colonic performance via metabolic degradation of the drug. Lower
surface area and relative tightness of the tight junctions in the colon can
also restrict drug transport across the mucosa and into the systemic
circulation.
Purvakarma
like local Snehana-swedana & slightly warm temperature of the Vasti may increase colonic
permeability; thus increasing the absorption.
Chief ingredients of VaitaranaVasti are having Tikshna Gunas; on virtue of its active
photochemicals it’s effect in Katishool,
Amavata therapy may be achieved through absorption of Vasti Virya i.e. entry of active
principles in systemic circulation through colon.
B). COLON CLEANSING
Colon cleansing come with many
beneficial effects out of which some are as follows:
v
Removal
of wastes and toxins:
With irregular bowel movements
and lack of defecation, faecal wastes start accumulating in the colon. Digested and undigested food
from the stomach travels to the small intestines. Here, only nutrients from the
food we eat are absorbed in the small intestines and the rest of the food
matter containing dead cells, unhealthy or dead microbes and other harmful
bi-products then move on to the large intestine or colon. These are largely
waste materials with little nutrients except for some water and electrolytes
which can be absorbed by the colon for use in our body. However, if these
wastes are not removed from the body on daily basis, they began to putrefy and
a bacterial load starts to build up and in no time our colon is filled with
toxic substances.
Certain
unhealthy bacteria and microbes flourish in these waste products which will
undoubtedly cause harm to our body eventually. A parasite colon cleanse will effectively kill parasites and
destroy their eggs. Colon cleansing helps to remove these wastes and toxins
from the body before autointoxication takes place. At the same time, colon can
slowly recover its intended functions and return to its healthy state.
v
Better Absorption:
One
of the major effects of colon cleansing is better absorption. The frequent
layering of toxins and wastes over the intestinal walls in the colon blocks the
function of the villi. The villi are hair-like protrusions in the intestines.
The purpose of the villi is to slow the passage of food, and to allow food
particles to be trapped among these finger-like villi. This allows the blood
inside the villi to absorb nutrients in the digested food. Though the colon
only absorbs electrolytes and water, it still performs a very important
function as our body is made up of 70% water. If the function of the colon is
impaired, there is a likelihood of dehydration occurring. Therefore, when the
wastes and toxins are quickly removed from the colon, the villi can perform
their functions readily.
v
Function enhancement of
other organs:
An
unhealthy colon affects all the other organs as well. When a colon is stuffed
it compresses the liver, disturbing its functions. The liver is one of the
major organs for toxin removal in the body together with the colon, kidneys and
skin.
The
liver's role in detoxification is to convert and detoxify harmful toxins into
substances that can be safely eliminated from the body. When digestion is poor,
bacteria in the intestines began to multiply when putrefaction takes place and
create toxins. These toxins can damage the mucosal lining of the intestine,
which increases its permeability and allows toxins to enter the bloodstream and
gain systemic access to all areas of the body. This places additional stress in
both the liver and kidneys. An unhealthy liver leads to an unhealthy kidney
this is a vicious cycle.
A
healthy colon helps to remove the wastes before they become toxic. So, having a
healthy colon is the first major step to ensure that the other organs can
perform their functions efficiently.
Impaired
functioning of colon leads to accumulation of toxins which can be stated in
Ayurvedic terms as Ama formation. Thus by colon cleansing action Vasti prevents Ama formation which is
responsible for deterioration of the amavata and katishoola vikara.
C)
Influence
through ENS (Enteric Nervous System)
v ENS
(Enteric Nervous System) is Substantial group of neurons
v It
is capable of Autonomous reflex without influence of central nervous system.
v More
than 500 million neurons present in the ENS (Enteric Nervous System) so it’s
called “second brain”.
v There
are so many similarities between CNS-ENS regarding cellular structure,
neuro-peptide secretion and specific functions.
v And
recent studies have shown that there is great influence of CNS and ENS (Enteric
Nervous System) on each other.
In this way, Vasti may
produce Neuromuscular remodelling, pain modulation by influencing ENS (Enteric
Nervous System) and there by CNS (Central Nervous System).
D)
Influence on Bacterial Flora
v Vasti
influence the normal bacterial flora thus it increases the endogenous synthesis
of Vitamin B12, Vitamin K etc. Vasti makes the whole metabolism normal.
v Production
of Thiamine with the help of bacteria, which is necessary for nerve conduction
and which is produced in large intestine, may be controlled by Vasti.
