nasya karmukata
DESCRIPTION
it is mode of action of nasya drugs.TRANSCRIPT
NASYA
KARMUKATHA
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
Cross-sectional view
Pathways for nasal absorption
Nasal site of drug spray & absorption
CROSS-SECTIONAL VIEW
a – nasal vestibule d – middle turbinate
b – palate e – superior turbinate (olfactory mucosa)
c – inferior turbinate f – nasopharynx
Site of drug
spray &
absorption
Pathways for nasal
absorption Absorption through the olfactory neurons
- transneuronal absorption. Olfactory epithelium is
considered as a portal for substances to enter CNS
Absorption into the cerebrospinal fluid
Absorption through the supporting cells & the
surrounding capillary bed
- venous drainage
Transneuronal absorption
Olfactory nerve – 1st cranial sensory nerve
Venous drainage
•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
Nasal pH
Factors
affecting
drug
absorption
Drug concentration
Vehicle of drug delivery
Mucosal contact time
pH of the absorption site
Size of the drug molecule
Relative lipid solubility
Degree of drug’s ionization
Physiological effects
- Drug metabolism in the respiratory tract &
reduction of systemic effect
- Mucociliary transport causing
increased or decreased drug residence
time
- Protein binding
Physiological effects....
- Local or systemic effects of propellants,
preservatives, or carriers
- Local toxic effects of the drug
Eg., edema, cell injury, or altered tissue
defenses
1. Effect of particle size
2. Effect of molecular size
3. Effect of solution pH
5. Effect of drug concentration
4. Effect of drug lipophilicity
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
- Intermediate particles (3 to 7 microns) reach the
actual site of action
- Small particles (< 3 microns) will be lost in exhaled
breathe
2. Effect of molecular size
- A good systemic bioavailability can be achieved for
molecules with a molecular weight of up to 1000
Daltons when no absorption enhancer is used
- Higher the molecular size, lower the nasal absorption
2. Effect of molecular size.....
Absorption enhancers: Polyacrylic acid
Sodium Glycocholate
Sodium Deoxycholate
Polysorbate 80 etc.
- With the assistance of absorption enhancer, a good
bioavailability can be extended to a molecular
weight of at least 6000 Daltons
3. Effect of solution pH
- Nasal absorption is pH dependent
- Absorption is lower as the pH increases beyond
the dissociation constant
- Absorption is higher at a pH lower than the
dissociation constant (pKa) of the molecule
4. Effect of drug
lipophilicity- Polar (water soluble) drugs tend to remain on the
tissues of the upper airway
- Lipid soluble drugs are absorbed more rapidly
than water soluble drugs
- Non-polar (lipid soluble) drugs are more likely to
reach distal airways
5. Effect of drug
concentration
- The absorption follows first-order kinetics
- Absorption depends on the initial concentration of
the drug
Nasya dravya karmukata
Nasya dravya 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)