Exam 2 Flashcards
What is a polymer?
A substance whose molecules consist of many parts or units
What are the types of ploymers?
Linear (homopolymer and block copolymer), crosslinked, branched, dendrimers
Where does the unique property of polymer come from?
The linkage of many monomers together
Why biodegradable polymers?
They could benefit us by decreasing our usages of crude oil by using a renewable source of corn.
What is the role of polymers in sustained drug delivery?
These crosslinked polymers coat the outside of the drug and swell and deswell in response to changes in the environment. By swelling and deswelling, it allows more and less drug out in a sustained manner. The polymers can also be degraded.
What are the advantages and disadvantages of mucosal drug delivery?
Advantages -Avoid the first-pass effect -Relative ease and convenience Disadvantages -Small area of absorption (nasal, oral) -Taste (oral) -Delivery limited by molecular weight of a drug -Local tissue irritation, sensitivity to pathologic conditions
Describe Mucus
- Secreted by goblet cells or specialized cells (salivary glands)
- Contains mucins (glycoproteins), lipids, inorganic salts, and ~83% water
- Mucus coats nearly all entry points to the human body that are not covered by skin
- Protects the mucosa in stomach from HCl
- Keeps the mucosal membrane moist
- Diffusion barrier for drugs
What are the purposes of mucoadhesion?
For slow absorption of drugs
For immobilization on desirable sites
What are the mechanisms of mucoadhesion?
Electrostatic interaction
-Positive charge of polymer vs. negative charge of sialic acid in mucin
Covalent bonding
-Disulfide bond between thiolated polymer and cysteine-rich portion of mucin
Hydrogen bonding
-(-COOH, -OH, -NH2)
Polymer interpenetration
What are the properties of mucus relevant to mucoadhesion?
- Contains mucins (glycoproteins)
- Mucus coats nearly all entry points to the human body that are not covered by skin
- Negative charge of Sialic Acid in Mucin
- Cysteine-rich subdomains forming intra-and/or intermolecular disulfide bonds
What are the drug properties desirable for mucosal delivery?
- lipophilic
- small M.W.
- Others may need absorption enhancers
Sublingual vs. Buccal
Sublingual
-relatively permeable
-Fast onset
Buccal
-Relatively less permeable than sublingual
-Slower absorption & onset of action than sublingual
-Less influenced by saliva
-Suitable for sustained delivery applications: Mucoadhesive dosage forms based on polymers
What nasal sections are important for systemic drug absorption and potential drug delivery to CNS?
Respiratory region in nasal cavity
What is a potential risk of nasal products?
Can cause the loss of sense of smell
What are the requirements and challenges in ocular drug delivery?
Requirements
-Need to be clear
-Good corneal penetration
-Prolonged contact time with the corneal epithelium
-Simplicity of use
-Non-irritating, comfortable
Challenges
-Loss due to dilution in the tear film, fluid spillage, drainage
-Short residence time
-Not much flexibility in formulation adjustments
