target release- part 2

Question 1

what is gastro-retentive drugs

Answer 1

• anything for dosage form can stay in stomach for as long as possible

Question 2

when would gastro-retentive drugs be helpful?

Answer 2

• Useful for drugs with narrow absorption window in intestine
-for local action

Question 3

what are some approaches for gastro-retentive delivery?

Answer 3

• Effervescent systems that generate gas and float
• Low density systems or hydrodynamically balanced
systems (contain buoyant material) that float
• Bioadhesive devices – some controversy due to
mucus layer resulting in shedding off of device
• Swelling or extendable systems that expand to a size
larger than the pylorus (but must be swallowed!)

Question 4

what are some key information about gastroretentive dosage forms - floating system?

Answer 4

Example: Gaviscon

• Used to treat oesophageal reflux

Question 5

how does the bioadhesive system work?

Answer 5

• Forms a protective layer on all internal epithelial surfaces of GI tract
• Interest due to possibility of retaining dosage form in specific region of GI tract and perhaps also having sustained release

Question 6

how does swelling and extendable system work?

Answer 6

-swell and expand in size in the stomach so there is a slow release

Question 7

what is the rationale for targeted control delivery to the colon?

Answer 7

a) The local treatment of diseases which affect the colon, such as Crohn’s disease and inflammatory bowel disorders
B) The systemic absorption of proteins.
c) The extended absorption of conventional molecules for sustained-release dosage forms

Question 8

what can be used for pH controlled systems?

Answer 8

• Enteric coat can be applied to a formulation (ie pellets, tablets or capsules)
-• Most common materials used are the Eudragits, which are a family of copolymers of methacrylic acid and methylmethacrylate. These materials are insoluble in the acid conditions in the stomach, but will dissolve at higher pHs, each Eudragit being designed to dissolve at a different pH.

Question 9

how can Utilisation of colonic bacterial azoreduction occur?

Answer 9

The colonic bacteria then cleave the azo bond generating the independent 5-ASA and sulphapyridine molecules. 5-ASA exerts its therapeutic effect locally and is essentially unabsorbed

Question 10

how can Utilisation of colonic bacterial polysaccharidases occur?

Answer 10

• In humans, the colon is the site of degradation of polysaccharides from the diet such as amylose, pectin, guar gum, chondroitin etc.
• By incorporating one or more of these materials into the dosage form, it would be expected that colonic targeting could be obtained.
• Two main methods have been used: formation of a hydrogel system or the use of a polysaccharide coat.

Question 11

how can time-released system occur?

Answer 11

• The Pulsincap consists of an insoluble capsule body containing the drug formulation and is sealed with a hydrogel plug
• After oral administration the hydrogel plug slowly hydrates and swells until it is expelled from the capsule body, thus exposing the drug formulation for dissolution

Question 12

how does Egalet time released work and what’s it made from?

Answer 12

Egalet® Two-Component System
• A matrix is surrounded by a water- impermeable, non-eroding, hard shell made of polylactic acid (PLA) that creates a cylinder, with the API-containing matrix exposed at both ends
• Manufactured by co-extrusion (hot melt extrusion)
• The shell serves to limit the portion of the matrix’s surface area that is exposed to the GI tract for tailoring drug release rate