Injectable Formulations Flashcards
Explain the difference between Small Volume Parenteral (SVP) & Large Volume Parenteral (LVP)
SVP - hermetically (airtight) sealed in a container of 100mL or less
LVP - liquid intended for infusion and hermetically sealed in a container of >100mL
What are some reasons for the use for injectables? (8)
1) Deliver systemically when other route not available
2) Exert direct control (e.g. anaphylaxis)
3) Correct rapid electrolyte imbalance and parenteral nutrion
4) Target specific areas (intrathecal, intra-articular)
5) Local action (anaesthetic)
6) Minimise systemic S/Es
7) Unconscious patients
8) Un-cooperative & Un-controllable patients
What are the 3 primary routes of parenteral administration
Intravenous (IV)
Intramuscular (IM)
Subcutaneous (SC)
List 5 categories of injectable formulations
1) Solutions
2) Suspensions
3) Emulsions
4) Dry solids / Liquid concentrates requiring reconstitution with suitable solvents to form sterile solutions
5) Dry solids requiring reconstitution with vehicles to form sterile suspensions
List some formulation issues that might arise in injections
1) Volume of injection
2) Solvents (solubility)
3) Types of vehicles (aqueous-based vs water miscible solvents)
4) Excipients (Buffers & Antioxidants)
5) Preservatives
6) Tonicity
What must you consider in IV injections when it comes to its volume?
The Rate of administration.
5mL = 1 mL per 20 seconds 100-1000mL = infuse 4-24 hours
List 5 desirable properties of injectable solvent
1) Pharmacologically inert
2) Non-toxic, Non-irritating, Non-sensitizing
3) Fluid at body temperature
4) Miscible with body fluids
5) Capable of being sterilized
What are some methods of increasing solubility?
- Co-solvents
- pH manipulation
- Complexation
- Solubilisation
List 3 desirable properties of a co-solvent
1) Effective at maintaining solubility
2) Physically and chemically stable
3) Unaffected by changes in pH
What is the purpose of Water Miscible Solvents and what are some examples?
They are used to enhance solubility, thus stabilising the drug.
Some examples include:
- glycerol, ethyl alcohol, propylene glycol, polyethylene, glycol 300 and 400
- These are all pharmacologically inert & miscible with body fluid.
- However, they can be irritating and increase toxicity
What type of injections are usually non-aqueous-based?
Intramuscular.
It uses biocompatible metabolisable oils, such as:
- peanut, sesame, corn, olive and cottonseed oil
Explain the term “Guest-Host” interaction and its benefit
Used in context with a cyclic polysaccharide solubilising agent that has a hydrophilic exterior and hydrophobic cavity.
“Guest-host” interaction involves releasing the “guest” from the cavity instantaneously into body fluid.
This increases its solubility, decreases the irritation and decreases the IM precipitation.
Why is air (O2) in the vials of oily injections replaced by N2?
Because the air will oxidise the oil and cause it to precipitate
What sort of injectable formulation allows a depot effect
Non-aqueous-based injections (e.g. oily injections).
Allows slow release of drug from oil and fatty tissues to have a prolonged action (e.g. 2-4 weeks)
List 4 reasons why buffers are used
1) For Solubility (weak acids dissolve stronger in stronger bases)
2) For Stability (prevent degradation due to pH)
3) To maximise biological activity
4) To prevent tissue damage (ideal 7.4 pH)
