Injectable Depot formulations

Question 1

What are the advantages and disadvantages of parenteral administration?

Answer 1

Advantage:
- Avoids first pass metabolism and increases bioavailability
- More rapid and predictable absorption, more accurate selection of appropriate dose
- Local effects may be achieved. E.g. steroids into joints, or even intraocular injections to
treat eye diseases.
- For emergency therapy, for unconscious patients, or patients experiencing nausea and
vomiting, emesis
Disadvantage:
- Painful/ poor patient compliance
- Expensive
- Difficult to self-administrate
- Difficult to reverse the effects of the drugs once administered

Question 2

What are the routes of parental administrations?

Answer 2

Intravenous
Intramuscular
Subcutaneous
Intradermal

Question 3

Can water-in-oil emulsions be administered by the intravenous route?

Answer 3

No, this is because suspended drug particles can block capillaries and the oil base of the
water-in-oil injection can cause fat embolism, and therefore block blood vessels.

Question 4

How can water-in-oil emulsions/ suspensions be given parentally?

Answer 4

By subcutaneous or intramuscularly

Question 5

Where are subcutaneous injections administered? Where are the injection sites?

Answer 5

Subcutaneous injections are administered into loose connective and adipose tissues beneath
the dermal skin layer. Injection sites include the abdomen, upper arm and upper leg

Question 6

How much mls of subcutaneous injection can you administer?

Answer 6

1ml

Question 7

What are the advantages and disadvantages of the subcutaneous route?

Answer 7

Well vascularised so rapid absorption
Disadvantage – slower onset of action and less total absorption of therapeutic agents
compared to other parenteral routes

Question 8

What is drug absorption?

Answer 8

The movement of drug from the site of administration into the bloodstream is the process of drug absorption

Question 9

How are long-acting injectables frequently administered?

Answer 9

IM and subcutaneously

Question 10

How can we achieve controlled drug release via the parenteral route of administration?

Answer 10

Implants or injectable depots

Question 11

What is an implant?

Answer 11

An implant is a single unit drug delivery system that has been designed to deliver a drug at a therapeutically desired rate over a long period of time.

Question 12

Compare and contrast the differences for depots and implants

Answer 12

Implants:
Used for more than 3 months and are invasive. They require large needles or surgical procedures and there is no dose flexiblility.

Injectable depots:
Used for 1-3 months
Smaller needles
Less invasive
Possible dose flexibility

Question 13

When can we use depots?

Question 14

Discuss the advantages and disadvantages of using Depots?

Question 15

Compare the factors needed to be considered for IM vs SC for long-acting injections.

Question 16

What are the two important steps that must occur following the administration of a depot injection?

Question 17

How long do oil based injections last in comparison to polymer-based microspheres?

Question 18

What are oil based injections?

Question 19

What factors influence drug levels following depot administration?

Question 20

What governs the release rate of paliperidone?

Question 21

How can the drug activity of poorly activated salts be further prolonged?

Question 22

How can we control surface area for dissolution?

Question 23

What are the important physiochemical factors?

Question 24

Permeation type microcapsules are a type of encapsulated depot preparation. Explain how the drugs are released in permeation type microcapsules.

Question 25

Diffusion matrix microspheres are a type of encapsulated depot preparation. Explain how the drugs are released in this preparation.

Question 26

What are the mechanisms of drug release from microspheres?

Question 27

Give an example of a drug that has a polymer matrix.

Question 28

Give examples of synthetic polymers and natural polysaccharides.

Question 29

What are the four stages of polymer degradation in apolymer matrix?

Question 30

What are some of the positive characteristics of PLGA microparticles that make them good injectable materials for drug-depot systems?

Question 31

How can injectable microspheres be prepared?

Question 32

What should be included in the formulation of PLGA injectables?

Question 33

How is the buprenorphine controlled-release depot injection formulated and how is controlled release obtained?

Question 34

Other antipsychotic drugs available as long-acting injection formulations include haloperidol decanoate, olanzapine pamoate monohydrate and
paliperidone palmitate.
How are these formulated and how is controlled release obtained for
each of them?

Question 35

How is the risperidone controlled release depot injection formulated
and how is controlled release obtained?