it is mode of action of nasya drugs.

1. A H
Y T
S A
A K
N U
M
R A
K A

2. The respiratory tract, which includes the
 nasal mucosa
 hypopharynx
 large airways &
 small airways
provides a relatively large mucosal surface
area of approx. 100 m (in normal adult) for
drug absorption

3. Cross-sectional view
Nasal site of drug spray & absorption
Pathways for nasal absorption

4. VIEW
a – nasal vestibule d – middle turbinate
b – palate e – superior turbinate (olfactory mucosa)
c – inferior turbinate f – nasopharynx

5. Site of drug
spray &
absorption

6. Pathways for nasal
absorption
 Absorption through the olfactory neurons
- transneuronal absorption. Olfactory epithelium is
considered as a portal for substances to enter CNS
 Absorption through the supporting cells & the
surrounding capillary bed
- venous drainage
 Absorption into the cerebrospinal fluid

7. Transneuronal absorption
Olfactory nerve – 1st cranial sensory nerve

8. Venous drainage

9. Nasal pH
•Nasal secretion of adult : 5.5-6.5
•Infants and children: 5-6.7
•It becomes alkaline in conditions such as
acute rhinitis, acute sinusitis.
•Lysozyme in the nasal secretion helps as
antibacterial and its activity is diminished in
alkaline pH

10. Drug concentration
Factors Vehicle of drug delivery
affecting
Mucosal contact time
drug
Degree of drug’s ionization
absorption
pH of the absorption site
Size of the drug molecule
Relative lipid solubility

11. Physiological effects
- Drug metabolism in the respiratory tract &
reduction of systemic effect
- Protein binding
- Mucociliary transport causing increased
or decreased drug residence time

12. Physiological effects....
- Local toxic effects of the drug
Eg., edema, cell injury, or altered tissue
defenses
- Local or systemic effects of propellants,
preservatives, or carriers

13. 1. Effect of particle size
2. Effect of molecular size
3. Effect of solution pH
4. Effect of drug lipophilicity
5. Effect of drug concentration

14. 1.Effect of particle size
(aerodynamic size distribution)
- Access to distal airways is a function of particle size
- Large particles (> 7 microns) will be lost in the
gastrointestinal tract
- Small particles (< 3 microns) will be lost in exhaled
breathe
- Intermediate particles (3 to 7 microns) reach the
actual site of action

15. 2. Effect of molecular size
- Higher the molecular size, lower the nasal absorption
- A good systemic bioavailability can be achieved for
molecules with a molecular weight of up to 1000
Daltons when no absorption enhancer is used

16. 2. Effect of molecular size.....
- With the assistance of absorption enhancer, a good
bioavailability can be extended to a molecular
weight of at least 6000 Daltons
Absorption enhancers: Polyacrylic acid
Sodium Glycocholate
Sodium Deoxycholate
Polysorbate 80 etc.

17. 3. Effect of solution pH
- Nasal absorption is pH dependent
- Absorption is higher at a pH lower than the
dissociation constant (pKa) of the molecule
- Absorption is lower as the pH increases beyond
the dissociation constant

18. 4. Effect of drug
lipophilicity
- Polar (water soluble) drugs tend to remain on the
tissues of the upper airway
- Non-polar (lipid soluble) drugs are more likely to
reach distal airways
- Lipid soluble drugs are absorbed more rapidly
than water soluble drugs

19. 5. Effect of drug
concentration
- Absorption depends on the initial concentration of
the drug
- The absorption follows first-order kinetics

20. Nasya dravya
karmukata

21. karmukata
 Substances which produces smell uaually have certain
characterstics.
1.Volatile
2.they are atleast slightly water soluble
3.they are usually highly lipid soluble.
 The cilia of olfactory cellls and the portions of the body of the
olfactory cells relatively contains large quantities of lipoid
materials.
 A substance which is lipid soluble can cause marked stimulation of
an olfactory cell.
 The substance which is given through the nostrils can irritate the
mucosa of the nose and drains the accumulated phlegm through the
nostrils.(in teekshna nasya)