Vaginal and rectal preparations

Question 1

What are the local uses of rectal drug delivery?

Answer 1

laxatives
haemorrhoids
inflammatory bowel disease

Question 2

What are the systemic uses of rectal drug delivery?

Answer 2

pain

seizures

Question 3

What are the characteristics of a good vehicle

Answer 3

melt at body temp
solidify quickly after melting
easily moulded and removed from mould
be stable when molten
release active ingredient
non toxic and non irritant (inert)

Question 4

What can the vehicle be made of in rectal drugs and give examples of each type?

Answer 4

• Fatty bases e.g. theobroma oil and synthetic fats such as hydrogenated vegetable oils.
• Water soluble bases e.g. macrogels and mix of glycerol water and gelatin. Macrogels are slow release but more common in pessaries.

Question 5

What are the other excipients in rectal drugs and elaborate on each?

Answer 5

• Viscosity enhancers e.g. colloidal silicon oxide, these create a gel like system for slower release of drug
• Lecithin, this is used when drug conc is high to help blood flow properties
• Surfactants, to create emulsion systems.

Question 6

What is stability affected by?

Answer 6

Heat - especially fatty bases (low temp is best)
Light - packaging
Moisture - especially water soluble bases
Therefore, they have short shelf lifes

Question 7

What can happen to water soluble bases?

Answer 7

They can turn brittle and may need lubricating before admin

Question 8

Discuss enemas:

Answer 8

They are oily/aqueous solutions. They can be a foam or in an aerosol canister. They don’t require melting or dissolution. Volume is variable and are contained in plastic bottles with special nozzles.

Question 9

What are the advantages of rectal drug delivery?

Answer 9

• It is useful when the oral route isn’t available as it may not be orally active
• It avoids problems with GIT absorption
• Avoids 1st pass metabolism for systemic action
• Rapid local action

Question 10

What are the disadvantages of rectal drug delivery?

Answer 10

• Patient may not prefer this route of admin
• Slow and incomplete absorption
• Local irritation
• Difficult admin
• Difficult production
• Storage conditions

Question 11

What are formulations for vaginal drug delivery?

Answer 11

Pessaries, tablets, capsules, creams, gels, foams.

Most require an applicator.

Question 12

What are advantages of vaginal drug delivery?

Answer 12

• Drug isn’t orally active
• This route has a better availability for some drugs
• It avoids problems with GIT absorption
• Avoids 1st pass for systemic action
• Rapid local action and reduced systemic side effects

Question 13

What are the disadvantages of vaginal drug delivery?

Answer 13

• Patient preference
• Local irritation
• underwear staining
• difficult admin
• difficult production
• pregnancy and applicators
• compatibility with condoms

Question 14

What should you remember when making suppositories extemp?

Answer 14

Always make an excess