The main aim of the Ayurvedic Science is to attain Dhatusatmya (equilibrium of tissues) through Samana (pacification therapy) & Sodhana (Purification Therapy).
Nasya is one among the Sodhana procedures which is mainly used to eliminate the morbid doshas that are accumulated above the neck region.
NASA: Nasa is considered as the GATEWAY OF SIRAS. It is made of tarunasthi measuring 2 angula. The drug administered through nose eliminates only the morbid doshas that cause diseases in urdwajatru area.
The description of mode of action of nasya is not clearly mentioned in Ayurvedic classics
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In Ashtanga Sangraha, the action of nasya is told as:
The drug administered through nostrils reaches Sringataka marma (Sira marma by Nasa srota) spreads to murdha(brain), netra(eyes), srothra(ears) and kanda(throat); scratches the morbid doshas in supraclavicular region and expels them from the Uttamanga(head).
According to all of our Acharyas, Nasa is said to be the Gateway of Siras. This doesn’t mean that any channels connect directly to the brain but they might be connected through blood vessels or through nervous system (olfactory nerves etc.)
“Nasta: karma cha kurveetha sirorogeshu sastravith
Dhwaram hi siraso nasa thena tat vyapya hanthi than”
From modern point of view:
There is no direct pharmacological correlation between nose and brain. However the olfactory area is the only place in the whole human body where there is direct contact between the outer surface and the Central nervous system. It is known that the blood brain barrier is a strict security system that prevents the entry of certain drugs to the brain.
However the effect of drugs on brain, administered through nasal pathway can be seen in following examples:
- The nose is used as a route of administration for inhalation of anaesthetics drugs.
- Ethanol suspension of Insulin sprayed through nebulizer gave excellent results in rats without any allergy.
- Certain agents are used as decongestants in the treatment of paranasal sinusitis.
- In modern medicine system, anterior pituitary hormones, in the form of nasal spray are being used since a long time.
- In the same way, Vasopressin is already in the market in the form of nasal spray.
Thus, to understand the action of Nasya drug on Central Nervous system it is necessary to know the probable pathways of Nasya Dravya. On the basis of fractional stage of Nasya karma procedures, we can draw certain rational issues that are as follows:
Effect on Neuro-vascular Junction:
Specific posture during Nasya karma, like the lowering of head, fomentation of face seems to have an impact on blood circulation of head and face. The efferent vasodilator nerves are spread out on the superficial surface of face. They receive stimulation by fomentation and this may increase the blood flow to the brain.
Absorption and Transportation of drug administered by nasal pathway:
Keeping the head in lowering position and retention of medicine in nasopharynx help in providing sufficient time for local drug absorption. Any liquid soluble substance has greater chance of passive absorption through the cell of lining membrane.
The absorption of drug, promoted by massage and local fomentation can occur in two ways:
- By systemic circulation
- Direct pooling into intracranial region
- By Vascular path
- By lymphatic path
Nasya kala i.e. proper time and duration of drug administration is important factor. Form of drug used is also important. Keeping in view of the above said facts, it can be concluded that either the essence of Nasya or Nasya Dravya is reaching the brain and acting on important centres controlling the neurological, endocrine and circulatory functions and thus showing systemic effects.
