Parenterals Route Flashcards
Parenteral route is…
drug administration by injection
Advantages of parenteral: (3)
works for unconscious patients
intravenous route means rapid onset of action
avoids first pass metabolism, thus improves bioavailability
Disadvantages of parenteral: (3)
need a healthcare professional
needle stick injuries, needle phobia
shelf life shorter, expensive to store
Intravenous route..
via a surface vein, 100% drug absorption
Infusion provides..
a slow and controlled drug release rate
What can’t be administered via IV? (2)
water in oil emulsions - can block blood vessels
hypertonic / extreme pH drug solutions - cause inflammation and pain
Intra-arterial route..
via an artery
more invasive, less accessible
only used when IV access cannot be established e.g. pre-mature babies
Intra-cardiac route…
used only in life-threatening emergencies to produce a rapid, local effect in the heart
Intra-dermal injections..
into the skin between the epidermis and dermis
slow absorption (little interstitial fluid to faciliate drug diffusion) used for immunological diagnostic tests and vaccinations
Subcutaneous injections / hypodermic…
into the loose connective and adipose tissues immediately below the dermal skin layer e.g. abdomen /upper arms and legs
highly vascular site so rapid absorption
Intramuscular injections..
into the tissue of a relaxed muscle in buttock, thigh and shoulder
absorption is slower than subcutaneous
Intrathecal injection…
into the cerebrospinal fluid CSF in the subarchnoid space of spinal canal
allows drugs to bypass the blood brain barrier
100% drug absorption
Epidural injection..
in the epidural space between the dura mater and the vertebrae
Intra-articular injections…
into the synovial fluids of joints cavities
100% absorption
Intraocular…
into the eye
intacameral injections - in anterior chamber
intravitreal - in the vitreous chamber
All parenteral preparations must be…
sterile
as the drug bypasses the body’s natural defence mechanisms
Excipients may be added to…
adjust pH
increase solubility / stability / shelf life
preservatives
What are Endotoxins and Pyrogens?
What is the significance?
Endotoxins - lipopolysaccharides found in the outer membrane of Gram-negative bacteria.
Pyrogens - substances that cause fever, typically produced by bacteria or viruses.
Parenteral preparations must be free from these
Significance of particulates?
suspensions must be free of visible and sub-visible particles - or else they will travel through the venous system to the lung, preventing blood flow
Containers must be..
transparent
glass/plastic
effectively sealed
be airtight
Sterile productions can be in..
solutions
clear and free from particles
suspensions
suspended by shaking
emulsions
no signs of creaming or cracking
Aqueous injections for multiple dosing must contain…
an antimicrobial preservative unless its self-preserving
What are infusions like?
sterile aqueous solutions or emulsions
continuous phase is water
isotonic formulation with respect to blood
100ml - 1000ml
How are concentrates administered?
through infusion bags
diluted with saline or water for injection
How are powders administered?
required volume of diluent is added prior to administration
used for drugs with short shelf life after dissolved in solution
How are suspensions administered?
must first be dissolved before absorption takes place - allows slow and prolonged release thus can reduce dosing frequency.
What else may be added?
co-solvents e.g. ethanol
solubilising agents
antioxidants, extend product shelf life / nitrogen gas bubbled through
preservatives
ph adjusters and buffers
tonicity adjusting agents
suspending agents in suspensions
When are glass containers used?
for single use unpreserved products
type 1 glass used as there is little interaction with formulations.
but they are fragile and carry safety risk
