Nasal Drug Delivery

Question 1

what are the advantages of the nasal route of administration?

Answer 1

1. large SA
2. low enzyme activity
3. thin epithelium (short diffusion pathway)
4. non-invasive
5. direct route to brain possible
6. easy to administer
7. patient acceptability
8. Nasal-Associated Lymphoid Tissue (NALT)-good target for vaccines

Question 2

where does absorption occur in the nose?

Answer 2

across turbunates and the septum

Question 3

how are lipophilic drugs transported in the nose?

Answer 3

they are transported transcellularly either by:

a) passive diffusion
b) receptor/carrier mediated transport mechanisms
c) vesicular transport mechanism

Question 4

how are polar drugs transported in the nose?

Answer 4

they pass through the epithelium via gaps and pores between cells (paracellular)

Question 5

what is the size of the gaps between cells and what sized particles can pass through them?

Answer 5

size between cells: 10 Angstroms

size of particles that can pass through: 1000 daltons

Question 6

what is the bioavailability of polar drugs with a low molecular weight?

Answer 6

~10%

Question 7

which has a higher bioavailability, polar drugs with higher molecular weight or lower molecular weight?

Answer 7

lower molecular weight

Question 8

why are polar molecules poorly transported?

Answer 8

1. have low permeability
2. are rapidly cleared
3. degraded by enzymes

Question 9

what can be used to increase the bioavailability of a drug?

Answer 9

absorption enhancers and bioadhesives

Question 10

how does chitosan work?

Answer 10

• it is a positively charged bioadhesive that is non-toxic and non-irritant.
• it works by disrupting the tight junctions hence increasing the paracelluar transport of molecules

Question 11

why does sniffing cocaine cause euphoria rapidly?

Answer 11

• because of the direct pathway from the nasal cavity to the CNS and
• because the drug could concentrate selectively in specific regions of the brain.

Question 12

how does the nose deliver chemicals to the brain?

Answer 12

• by direct transport of chemicals across the olfactory region transcellularly or paracellularly.
• can also be transported intracellularly through axons to the olfactory bulb

Question 13

what is the target site of nasal vaccines?

Answer 13

the NALT (nasal-associated lymphoid tissue) which is in the pharynx as a ring of lymphoid tissue.

Question 14

what are the two major types of nasal vaccines?

Answer 14

1. particulate antigen delivery systems (antigen is entrapped or presented on particle surface)
2. Solution systems (antigen dissolved or suspended within a solution vehicle)

Question 15

what drains the NALT?

Answer 15

the posterior cervical lymph nodes