Lecture 10 Oral Drug Delivery Flashcards
Describe delayed release systems in oral drug delivery.
Delayed release systems are often coated immediate release tablets that provide a delay in the time to release the active ingredient, such as enteric coated tablets that resist gastric juices but dissolve in the small intestine.
What is the purpose of pH-sensitive coating in oral drug delivery?
pH-sensitive coatings are used to ensure that capsules dissolve in the stomach, protecting the beads inside from gastric mucous membrane irritation, preventing drug exposure to the environment, and allowing targeted drug delivery to specific sections of the gastrointestinal tract.
How does osmotic technology work in controlled drug delivery systems?
Osmotic technology involves a controlled delivery system using an osmotic pump where an osmotic agent is added to draw water into the tablet, resulting in a zero-order release profile that is independent of external factors.
Define HPMCAS and its pH sensitivity.
HPMCAS is pH-sensitive as it contains a carboxyl group, making it responsive to changes in pH levels.
What are the factors that can affect the dissolution of enteric coated formulations?
Factors include the type of polymer used for coating, coating thickness, gastrointestinal transit and pH, as well as the physiochemical properties of the tablet core, excipient combination, and processing factors.
Describe the elementary osmotic pump system.
It consists of a single-layer compressed tablet coated with a semipermeable polymer, with one small hole through which water is driven into the tablet core by the soluble drug, releasing the drug as a solution.
How does the push-pull osmotic system work?
The bottom layer contains a polymer that swells, causing the drug to dissolve and be released. The second layer serves to generate osmotic potential and hydrostatic pressure through swelling.
Define the advantages of push and pull osmotic systems.
They include better patient compliance, reduced side effects, release rate independence from hydrodynamics, pH-dependent release, in vitro and in vivo correlation, and potential for aesthetic or functional coating.
What are the disadvantages of push and pull osmotic systems?
Complex manufacturing process, limited drug loading capacity, potential local irritation and infection risk, patient distrust due to unmodified tablet elimination, and risk of drug dumping if tablets are broken.
Describe the limitations in drug loading for push and pull osmotic systems.
The drug loading is typically limited to approximately 25% of the total tablet weight due to the system’s design and functionality.
