lecture 22 - oral vs parenteral management Flashcards
what are advantages of parenteral drug administration?
drug is not broken down in GI tract
100% bioavailability
localised effect - eg injections into joint, ocular, intradermal
rapid inset of effect iv injection
drug administered in unconscious patient
delayed onset of effect/ few dosinfs
what are disadvantages of parenteral drug administration?
use of needle
painful
preparation needs to meet stringent specifications - expensive
limited self-administration
what happens with central line for IV dosing?
thrombophlebitis minimised
rapid dilution of drug in large volume of drug
not suitable to administered without emulsion fat embolism
not suitable to administered suspension - particles block capillaries
when are intracardiac injection used?
only life threatening emergency
administer drug directly into heart
what is absorption of intradermal like and when is it used?
slow absorption from injection site
typically used for vaccination
what is subcutaneous injection and its absorption rate?
injection into subcutaneous fat
aqueous solution or suspension
quite fast absorption (good vascular supply) and predictable
example: insulin
where is intramuscular used and absorption rate?
typically buttock, thigh or shoulder muscle
there is slower systemic absorption than subcutaneous
what are examples of intraspinal injection ?
intrathecal injection
epidural injection
what are intrathecal injections ?
only aqueous injections
intrathecal injections administers drug into cerebrospinal fluid
cerebrospinal fluid subarachnoid space between arachnoid mater and Pia mater
intrathecal injection is also used to introduce drugs that cannot cross the blood brain barrier eg antibiotics to tx meningitis or anticancer agents
what is epidural injection?
injection into epidural space eg spinal anaesthesia
what is intra-articular injections used for?
injection into synovial fluid of join cavities
aqueous solutions or suspensions
typical anti inflammatory drugs to txarthritic conditions
what are ophthalmic injections?
around or into the eye injections
intraocular injections into anterior chamber of the eye
what is intraviteral injection?
into vitreous chamber - behind lens
what are pahrmacopoerial requirements of injections?
sterility
excipients eg pH adjustment, isotonic, stability of drug
containers - transparent to permit inspection of contents
free from endotoxin and pyrogens
free of particulates
for emulsions for IV injection droplet less than 3micrometres to prevent oil embolism
what are the formulations for injections required?
vehicle for injections
preservatives
antioxidnats
pH adjustment
tonicity adjustment
