Oral Drug Delivery 3

Question 1

Describe a delayed release system

Answer 1

IR tablets that are coated to provide a delay in the time of release of active ingredient

Question 2

Describe an enteric coated tablet

Answer 2

Resistant to gastric juices but dissolves readily in the small intestine or colon

Question 3

Reasons why pH sensitive coatings are used

Answer 3

1. Drug causes gastric mucosa irritation e.g. NSAIDs
2. Protecting the drug from gastric environment e.g. duloxetine, PPI’s
3. Targeting the drug to a particular section of the GI tract e.g. colon specific therapy with 5-ASA

Question 4

List 3 enteric polymers and their dissolution pH

Answer 4

1. PVAP - pH 4.5 - 5
2. HPMCAS (aqoat) - pH 5.5 - 7
3. Eudragit - pH 5.5 - 7

Question 5

Factors that affect enteric coating dissolution

Answer 5

Can be split into 2 sections Coating & Tablet core

Coating - polymer used, thickness, GI tract pH, GI transit

Tablet core - water solubility of API, excipients used, compression force used to make tablet

Question 6

What issue to GI transit present with MR preparations

Answer 6

GI tract transit is highly variable
Presents problems for performance of MR systems

Question 7

What is the gastric emptying of tablets in fasted conditions

Answer 7

60 to 160 mins

Question 8

Benefits of using pellets or multi unit dosage forms

Answer 8

1. These dosage forms empty with less variability
2. For pellets, gastric emptying times in fed and fasted conditions are similar
3. Less risk of dose dumping

Question 9

How does gastric emptying differ between tablets and pellets

Answer 9

Gastric emptying variability is higher for tablets than pellets

Question 10

How does colonic transit differ between tablets and pellets

Answer 10

Colonic transit variability is higher for tablets than pellets

Question 11

What is didanosine and what is it indicated for

Answer 11

Didanosine is an NRTi
Used in the treatment of HIV infection
Needs administration with antacids to protect drug

Question 12

What are the issues with chronic antacid administration

Answer 12

Side effects - constipation, diarrhoea
Contraindicated in impaired renal function
Decrease the bioavailability of ketoconazole by altering gastric pH

Question 13

What is a logical way to protect an NRTi (didanosine) from the conditions of the stomach

Answer 13

Enteric coating

Question 14

What is SOMA

Answer 14

An indigestible self-orientating system for oral drug delivery of macromolecules

Question 15

What is LUMI

Answer 15

A luminal unfolding micro needle injector for oral delivery of macromolecules