Suppositories

Question 1

Define suppositories

Answer 1

A solid medical preparation that are introduced into body orifices (i.e. vagina, rectum and urethra)

Question 2

List the 3 types of suppositories

Answer 2

• There’s rectal which is inserted into the rectum for haemorrhoid treatment or pain relief
• Three also vaginal and urethral

Question 3

Outline the structure of the rectum

Answer 3

lower part of the large intestine. 15 to 20 cm long. Hollow organ with a flat surface, with only 3 major rectal valves

Question 4

Outline the structure of the anal canal

Answer 4

Found at the end of the rectum and is 2 to 3 cm long

Question 5

Describe the physiology of the rectum

Answer 5

Under normal conditions it is empty but filling provokes a defecation reflex
- Consists of 2 to 3 ml of mucous
- ph of 7.4 and little buffering capacity

Question 6

List/outline the 6 factors that influence the absorption of drugs from the rectum

Answer 6

1.** Stable **
2. Low enzymatic activity minimises breakdown of API before absorption
3. **Small fluid volume of 1-3 ml: helps in dissolution and absorption of suppositories
4. Neutral to slightly basic pH** ensures no degradation of API by harsh acidic or basic conditions
5. Small area ** - targeted and efficient absorption
6. Drained by rectal veins and lymphatic vessels** - facilitate the transportation of drug directly into bloodstreamin

Question 7

Outline the process of drug absorption into the rectum

Answer 7

1. Drug insertion into the rectum
2. Water is attracted and drug is dissolved or melted
3. Dissolved drug will diffuse out towards the rectal membrane
4. Drug passively enters the cappilaries

Question 8

What happens if medication is inserted too high in the rectum

Answer 8

If it is inserted too high, It can be absorbed into the superior rectal vein which travels to liver promoting first pass metabolism – lower bioavailability of drug.

Question 9

Why is it important to insert the drug in the lower part of the rectum

Answer 9

It will be directly enter the systematic circulation by entering the inferior rectal vein

Question 10

Exactly how far should the suppositories be inserted?

Answer 10

When it passes the anal spincter
Infants: approx 1/2 to 1 inch
Adults: approx 2 inches

Question 11

List the 2 types of suppository bases

Answer 11

1. Fatty bases
2. Water-soluble bases

Question 12

List the requirements for storage for suppositories

Answer 12

1. Need to be kept in a cool dry place below 25 degrees
2. Avoid direct sunlight
3. Protect from moisture
4. Refrigeration for some formulas

Question 13

Define displacement value

Answer 13

the amount of the drug that takes the same volume as 1 gram of the suppository base

Question 14

If Aminophylline has a DV of 1.3 then what does this mean?

Answer 14

1.3 grams of that drug will take the same volume as 1 gram of supp. base

Question 15

List 4 advantages of supp.

Answer 15

1. Avoids first pass metabolism
2. Provides both local and systematic effects
3. Suitable for patients with swallowing difficulties.
4. Less stomach irritation
5. Sustained drug release - beneficial for long term treatment

Question 16

List 3 disadvantages of supp.

Answer 16

1. Strict storage conditions
2. Bowel function interference
3. The rectum’s limited capacity restricts the amount of drug that can be administered

Question 17

Define vapour pressure

Answer 17

When the liquid and vapour are at the equilibrium its the pressure of the vapour above the liquid

Question 18

What does the Raoults Law tell us:

Answer 18

The ‘total pressure’ of all molecules in the gas phase