exam 2 lecture 2 Flashcards
parenteral routes of admin
IV - rapid, straight to blood stream, good for irritant drugs, suitable for large volume, least forgiving
IM
subQ
intradermal
intraperiotoneal
parameters for parenteral admin
has right potency
properly labeled
sterile
free of particles + pyrogens
isotonic
physiological pH
parameters for intra-spinal injections
has right potency
properly labeled
sterile
free of particles + pyrogens
isotonic
physiological pH
no preservatives
common isotonic vehicles
0.9% NaCl (saline)
5% dextrose aka D5W
isotonic + sterile solutions
NS
D5W
D2.5W / 1/2NS
components of parenteral product vehicles
water miscible products
ethyl alcohol
polyethylene glycol
propylene glycol
used to stabilize drugs
slow down hydrolysis
IM injection
IV preparation
PEG
can be used in IV concentrations as high as 40%
low hemolytic potential
oils
do not inject straight liquid oils into vein (IV) –> causes embolism
oil emulsion is OK for IV injection
- oil droplets are small
- no risk embolism
- solution is not emulsion
OIL solution can be admin IM
OIL solution is not OIL emulsion
antimicrobial preservatives
used for multiple dose preparations
benzyl alcohol - .9% is most common
parabens
cresol
not effective in oil based formulations
important info antimicrobial preservatives
only multiple use are allowed to contain antimicrobial preservatives
multiple use must contain preservatives
benzyl alcohol in neonates –> gasping syndrome
intraspinal admin must be free of anti-microbial preservatives
pH buffers
addresses solubility + stability issues w/ drug
use them as low concentrations as neccessary
common buffers
citrates: safe by IV, very irritating by IM or SC
acetates
phosphates: caution bc potentially fatal due to combining w/ calcium and precipitating –> need to be given together in PN preparations
buffer vs unbuffered
buffers are used to force the pH to a fixed value
unbuffered solutions are quickly diluted into physiological pH
want buffer as dilute as possible physiological pH in body takes over
antioxidants
metabisulfite salts: low pH
bisulfite: intermediate pH
sulfite: high pH
ascorbic acid
antioxidants get attacked by oxygen first –> protects drug
chelating agent
most common sodium EDTA
enhance antioxidant effect