colonic drug delivery Flashcards
what are the routes of administration for the medicines in the lower GIT?
- intestinal drug delivery
- parenteral
- rectal
what separates SI and the colon?
ileocaecal junction
how can the dosage form stay in the ileocaecal junction?
it dependeds on the dosage form
what is the role of the colon?
Remove liquid from incoming material & kneads colonic contents firmly → peristaltic waves covering only short distances
what affects the GI tract delivery?
if empty stomach/ light brekfast/ heavy brekfast/ empty stomach
why would you need drug delivery to the colon?
- A form of targeted drug delivery
- Local diseases, IBD such as Crohn’sdisease & ulcerative colitis •Systemic absorption of drug poorly absorbed or unstable in upper GIT, e.g. peptide and protein •Modified release dosage form, as chronotherapy to manage asthma, arthritis and hypertension
what are some of the different approaches to delivery in the colon?
- Utilising of presence of special bacterial flora of colon
- Utilising of pH variations along GIT & pH of an inflamed colon
- A time controlled drug release assuming that gastrointestinal transit follows a defined time pattern
- Combined approaches
how could you utilise colonic bacteria flora in drug delivery?
•Digested by enzymes of the colonic bacteria
–Polymer cross-linked with azoaromatic groups
–Pectin and pectin/chitosan mixtures
why would you speilise glassy a amylose?
–Chains of glassy a amylose entangles in fixed position by H bonds reduces flexibility of aamylose molecules –Not digested by pancreatic amylases
–Hydrolysed by bacterial aamylases
what is glassy a amylose?
- High amylose starches from genetic modified maize
- Contain amylose and amylopectin
- Use of butanol/water mixture
what is the mixed film produced by glassy a amylose?
water insoluble film forming polymers (e.g. ethyl cellulose)
•Affect film forming capability and film strength, degree of film swelling
•Drug release via diffusion
what happens when there is an aqueous disperson of an amylose-butanol complex.
when it is heated it loses butanol to give you an amylose solution
what happens to an amylose solution when colled or otherwise?
when cooled- precipitatated
retrogradation= phase separation and loss of water to give a gel
what happens to amylose gel when it cools fast/slowly?
slow- solid crystals
fast- further water loss and glassy amylose film
how do you test the efficiency of amylose coating films?
- Standard dissolution tests using–Simulated gastric fluid (pepsin)–Simulated intestinal fluid (pancreatinand taurocholicacid)
- Dissolution tests with solutions containing bacterial a-amylase (source: Bacillus licheniformis)
- Fermentation tests in faecal slurry
