Pharmaceutics: Rectal Drug Delivery

Question 1

What is rectal drug delivery?

Question 2

Why would rectal drug delivery be used?

Question 3

List types of rectal dosage forms

Answer 3

Suppositories

Enemas

Micoenemas

Foams, creams, gels + ointments

Question 4

What are the reasons for rectal drug delivery route?

Answer 4

Local conditions in rectum

Oral route unavailable

GI surgery

Vomiting episodes

Sleeping or unconcious

Old, young or mentally disturbed

Drugs with extensive FPM

Convenient night-time therapy

Question 5

What are the problems of rectal drug delivery?

Answer 5

Not popular

Inconvenient

Leakage

Proctitis

Bowel movements

Drug absorption = erratic

Question 6

What would be the local clinical use for rectal drugs?

Question 7

What would be the systemic clinical use of rectal drugs?

Answer 7

Suppositories or enemas for:

Pain relief

Nausea after chemotherapy

N+V

Arthritis

Seizures

Infections

Question 8

Draw diagram of rectal area

Question 9

Drugs administered high in rectum is carried to _____

Question 10

Drugs administered low in rectum delivered ______

Answer 10

Systemically by inferior rectal vein before passing through liver

Question 11

Where does rectal absorption occur?

Answer 11

Absorption across mucosal epithelium

Question 12

Which veins bypass liver?

Question 13

Speed of rectal absorption?

Question 14

What can reduce rectal absorption?

Question 15

What does rectal absorption depend on?

Answer 15

Disease state + retention time

Question 16

What can help influence rectal absorption?

Answer 16

Position of doage form

Question 17

What can influence retention time of rectal dose form?

Answer 17

Disease state/drug irritancy can alter toilet frequency

Diarrhoea = shorter

Constipation = longer

Drugs = slower

Irritant drugs stimulate evacuation

Question 18

How should drugs be designed for rectal drug delivery?

Answer 18

Requirements

• Must release drug
• Spread across epithelium
• Non-irritant

Environment

• Secretions - pH7, mucin
• Rectal environment has little buffering capacity to help drugs ionise

Question 19

Describe the benefits and challenges of different formulations designed for rectal use

Question 20

What are the common suppository bases?

Question 21

List issues with rectal drug release

Question 22

For rectal drug delivery, drugs should not retain in base.

How can drugs partition out of bases?