Nasal & Pulmonary Delivery Flashcards
(24 cards)
What types of drugs can diffuse trough the nasal epithelium?
Small and lipophilic
What is the main function of the nasal cavity?
Air conditioning
How can drugs bind to mucus?
Electrostatic interactions or hydrogen bonding
Mucus is 90-95% what?
Water
What is the difference between liquid drops and aerosols in nasal delivery?
Liquid spread throughout the cavity while aerosols are distributed according to particle size
Drugs can be metabolised in the nasal epithelium by what?
Carboxyl esterases, aldehyde dehydrogenase, epoxide hydrolases and glutathione s-transferasses, aminopeptidases, proteases, cyp450 enzymes
Temperature and humidity affect what of the mucus?
The water content
What is the frequency of nasal cycling?
2-6 hours
What promotes nasal clearance?
Common cold Rhinitis Asthma Hay fever B-adrenergics Cholinergics
What inhibits nasal clearance?
Anaesthetics
Antihistamines
Propranolol
Bike salts
What is the nasal area where BBB is not present called?
Olfactory region
How can drugs enter the brain nasally?
Paracellular diffusssion or axonal transport in olfactory region
What are the advantages to nasal delivery?
Convenient and accessible
Avoids acid environment and 1st pass
Large SA and highly vascularised
Rapid systemic delivery
What are the disadvantages of nasal delivery?
Mucus barrier
Rapid mucociliary clearance
Poor absorption of drug >50Da
Variability and adverse reactions
What are the 3 strategies for improving nasal delivery?
Alter mucus layer
Increase contact time with nasal epithelium
Penetration enhancers
What size particles deposit in the upper airways?
> 10um
What size particles deposit in the upper TB region?
7-10um
What size particles deposit in the lower TB region?
2-7um
What size particles deposit in the alveolar ?
0.5-2um
What are the 3 mechanisms of lung deposition?
Inertial impaction
Sedimentation
Brownian motion
What is the transcellular pathway?
Passive diffusion of small lipophilic drugs through the epithelium down a concentration gradient
What is the paracellular pathway?
Passive diffusion of small hydrophilic drugs down a concentration gradient between the cells of the epithelium
What are the advantages to pulmonary drug delivery ?
Rapid onset of action Large SA High blood flow High permeability Low metabolism Avoidance of 1st pass
What are the disadvantages to pulmonary drug delivery?
Complex delivery devices
Reproducibility
Mucus
Clearance
