Controlled drug delivery 1 Flashcards
What are controlled drug delivery systems?
Preparations designed in such a way that the release rate or location of active drug is controlled
What are 4 reasons for using controlled drug delivery systems?
- Reduce fluctuations in drug plasma concentrations
- Reduce dosing frequency-improve patient compliance
- Control delivery site
- Timed release
What are enteric coatings?
Tablets coated with a polymer that is insoluble in the highly acidic stomach, but dissolves int eh small intestine (>pH 5.5)
What kind of polymers are available for enteric coatings?
Cellulose derivatives
Methacrylic acid co-polymers
What is the release area for Eudragit D-55?
Duodenum
What is the release area for Eudagrit 100?
Jejunum
What 4 mechanisms are there for controlling drug release?
Water penetration controlled DDS
Diffusion-controlled DDS
Chemically-controlled DDS
Responsive DDS
What is used for swelling-controlled devices?
Hydroxypropyl methylcellulose
What is the release rate affected by for swelling controlled devices?
Polymer MW, concentration and chemical structure.
Drug concentration, solubility and location.
Geometry of tablet and modifications.
How is Geomatrix technology composed?
Hydrophilic HPMC core containing the drug.
One or two drug-free barrier layers which control swelling and surface area of core.
What are 8 different control capabilities that swelling controlled devices are capable of?
Zero order Quick slow Slow quick Binary Positioned Accelerated Delayed Multiple pulse
What is TIMER controlled release delivery system composed of?
Locust Bean Gum (LBG)
Xanthan
What does release rate of TIMER controlled release delivery system depend on?
LBG:X ratio
Drug concentration
Additional components-salts and water
Construction of tablet
What kind if delivery is possible for TIMER controlled release delivery system ?
Zero order
First order
Burst
Delayed
What steps are involved in TIMER controlled release delivery system ?
Water influx
Matrix swelling
Drug diffusion
Matrix erosion
What is the advantage of GEMINEX delivery technology?
Its ability to develop a combination drug product that has twp unique release profiles
What does a SyncroDose tablet consist of?
An inner core of drug and a surrounding compression coating containing TIMER based materials
What is lag time controlled by for SyncroDose tablet?
Variations in the two polysaccharides- xantham gum and locust beam gum
How does SyncroDose tablet delivery system work?
Controls rate of water ingress into coating and subsequent disintegration of core.
What can be modified for SyncroDose tablet to control release rate?
Coating layer
What happens to the coating of swelling controlled delivery systems after 0.37 hours?
Enters the stomach and outer polysaccharide begins to swell
What happens to the coating of swelling controlled delivery systems after 1.6 hours?
Proceeds along GIT and erosion of tablet coating begins to occur but substantial amounts remain in contact with the core preventing drug release
What happens to the coating of swelling controlled delivery systems after 3.42 hours?
entire coat has eroded and dispersed
What happens to the core of swelling controlled delivery systems after 0.37 hour?
Enters stomach and core remains intact
