Absorption of Drugs - Exam 3 Flashcards
definition of absorption of drugs
from the site of administration to the systemic circulation
drug factors affecting drug absorption
molecular size, lipid solubility, degree of ionization, dissolution in water, concentrative at absorptive site, route of administration
animal factors affecting drug absorption
blood flow, absorptive surface area, connective tissue, species, individual
the smaller the molecular size the ______ the penetration through the cell membrane pores
faster
the greater the lipid solubility the _____ the ability to dissolve in lipid bilayer portion of the cell membrane
greater
increased lipid solubility = ______ absorption
increased
the more non-ionized the drug (N>I), the greater the
absorption
oral absorption of ____ drugs faster than solid drugs
liquid
oral absorption of solid drugs depends on their
rate of dissolution
the higher the concentration the ______ the absorption
faster
route of administration in order fastest to slowest
inhalation, sublingual, IM, SQ, enteral
increased blood flow _______ drug absorption
increases ; “more blood, more drug”
what 3 things can modify blood flow
drugs, physiological factors, disease
epinephrine injection causes local vasodilation which
decreases blood flow & absorption
inflamed tissue has higher blood flow so a topical drug may have increased
absorption
heat or massage of intramuscular injection site increases
blood flow & absorption
sympathetic stimulation
increases blood flow to skeletal muscles
decreases blood flow to GI tract & subcutaneous tissue
“fight or flight”
parasympathetic stimulation
increases blood flow to skeletal muscles
decreases blood flow to skeletal muscles
“rest & digest”
the greater the surface area, the more _______ absorption will occur
efficiently
the presence of connective tissue will decrease ______, because……
absorption ; it is fibrous, not vascular
individual differences include
age, body condition, medical state, variability
what is the main site for absorption of enterally administered drugs & why
upper part of the small intestine; extensive surface area & rich in blood supply
rate of absorption depends on
gastric emptying
drug and disease examples that can modify the rate of gastric emptying include
blood flow to the GI tract, slowed GI motility due to vomiting, presence of other material in the GI tract like hay might prevent absorption, species differences like ruminant or monogastric, etc.
