Rectal And Vaginal Drug Delivery

Question 1

What are the 3 veins in the rectum and where do they drain?

Answer 1

The lower and middle haemorrhoidal veins drain directly into the general circulation, while the upper haemorrhoidal vein drains into the portal vein that flows to the liver

Question 2

What are the different formulations used for rectal drug delivery?

Answer 2

Suppositories are most common

Also, tablets, capsules, ointments and enemas

Question 3

What are the two classes of suppository vehicles?

Answer 3

Oil base (glyceride-type fatty compounds, lipophilic in nature)
Water-soluble base (glycerol-gelatin mixtures or PEGs, hydrophilic in nature)

Question 4

What are general requirements for suppository vehicles?

Answer 4

It should melt in the body or dissolve and mix with the available volume of rectal fluid
It should exhibit sufficient physiochemical characteristics for industrial-scale production (good flow ability, viscosity, fast solidification, easy removal from the moulds)
Chemically and physically stable during storage

Question 5

What are some factors that need to be considered when choosing drug candidates for rectal drug delivery?

Answer 5

Drug solubility
Particle properties
Drug loading

Question 6

When is rectal administration appropriate?

Answer 6

If the patient is unable to make use of the oral route
If the patient is unconscious or uncooperative
When a drug compound is less desirable for oral administration (GI side effects, if the drug is susceptible to extreme pH of the stomahc or unstable to enzyme attack)