ccc Flashcards
What is the main challenge in ophthalmic drug delivery?
To prolong drug residence time and guarantee appropriate ocular permeation.
What are the two approaches to overcome challenges in ophthalmic drug delivery?
- Alternate delivery routes for direct access to target sites.
- Development of novel drug delivery systems.
What are the static barriers to drug penetration into the eye?
- Cornea
- Sclera
- Bruch’s membrane
- Retinal pigment epithelium (RPE)
What are the characteristics of the corneal barrier?
- Epithelium (lipophilic)
- Stroma (hydrophilic)
- Endothelium (lipophilic)
What influences permeation behavior across the corneal barrier?
- Ionization grade
- Log P
What is the composition of the sclera?
- Episclera
- Sclera proper (Tenon’s capsule)
- Lamina fusca
True or False: Diffusion of hydrophilic molecules is lower than lipophilic molecules in the sclera.
False
Describe the role of the retinal pigment epithelium (RPE).
The RPE forms a barrier between the retina and the choroid, maintaining retinal health and enabling photoreceptor function.
What are the dynamic barriers to drug penetration into the eye?
- Spilling upon instillation
- Tearing and reflex tearing
- Drainage through ductus nasolacrimus
- Conjunctival/episcleral clearance
What is the significance of metabolic barriers in ocular drug delivery?
They involve drug-metabolizing enzymes in ocular tissues, particularly in the ciliary body and RPE.
What are the new challenges associated with small molecules in ophthalmic formulation development?
- Poor water solubility
- Increased difficulty in developing eye drop solutions
- Alternative formulations often less stable
What are some large molecules used in ocular formulations?
- Peptides
- Proteins
- Nucleic acids
What is a consequence of using large molecules in ocular formulation development?
Increased complexity and longer development times.
What is the trend in drug delivery systems for treating diseases in the back of the eye?
A shift from topical forms to invasive forms to improve drug delivery.
Fill in the blank: The major goal in ocular delivery is to achieve an effective concentration of the drug in the _______.
[target tissues]
What strategies can optimize bioavailability in ocular drug delivery?
- Screen for optimal molecule
- Increase the number of free molecules
- Increase residence time
- Enhance permeation rate
What is the conclusion regarding drug delivery to the eye?
It remains challenging due to the eye’s structure, and new approaches are being researched.
What are the implications of the increased invasivity in ocular drug delivery?
- Increased duration of action
- Greater need for effective delivery to the back of the eye
