RoA - Parenteral Flashcards
Parenteral advantages
Rapid onset of action
Avoids 1st pass metabolism
Unconscious patients can use
Allows higher conc. if drug in system
Parenteral disadvantages
Requires health profession to administer Needle stick injuries Needle phobia Shelf life shorter than oral Requires refrigeration Formulation/manufacturing costs more
Excipients - vehicle for injection
Water. Saline for injections
Stabilising agents added to avoid drug dissolution
Co solvent may also be used (ethanol)
Excipients - preservatives
Anti-microbial used in many products
Eg:benzoic acid
(Co-solvent can aid drug dissolution and antimicrobial effect)
Excipients - antioxidant
Reduce drug degradation by oxidation increasing shelf life
N gas bubbles through to displace O2
Excipients - pH adjusters/buffers
3-9 pH and is adjusted by acidifying/alkalising agents
Buffet to maintain pH
Excipients - tonicity adjusting agents
IV infusion must be isotonic
NaCl can be added to hypotonic solutions
Dilution prior to administration can make hypertonic solutions isotonic
Excipients - suspending agents
Used in suspensions to ensure drug can be readily re-suspended by shaking (Eg:polysorbates)
Why does parenteral RoA need to be sterile?
All parenteral injectable preparations must be sterile as drug administered straight into circulation so bypass the body’s natural defence system and barriers
Aseptic technique used
What are parenteral excipients added for?
Adjust pH Increase drug stability Increase shelf-life Increase drug solubility Adjust isotonicity to match human blood Act as preservative
What should excipients not do?
Not effect drug action or cause any side effects/toxicity
Types of parenteral containers
Ampoules - type I glass but new plastic
Vials - type I glass with synthetic rubber
Infusion bag/bottle - for large volumes
