chapter 3 (how drugs work in body and mind) Flashcards
4 routes of drug administration
- oral administration
- injection
- inhalation
- absorption through skin/membranes
what is the safest way to administer a drug?
orally
what characteristic is necessary of drugs to pass through the fat membrane between the gastrointestinal tract and blood capillaries?
substances must be lipid-soluble (soluble in fats)
intravenous (i.v.)
into a vein. as injection, takes approx. 15 seconds.
intramuscular (i.m.)
into a muscle. as injection, usually into large muscle like upper arm, thigh, buttock. absorbed into bloodstream through capillaries serving muscle. takes longer than i.v.
subcutaneous (s.c./sub-Q)
underneath the skin. as injection, slowest method because of less abundant blood supply. only small amounts.
intranasal
into the nasal cavity.
inhalation
breathing in particles of the drug through smoke or vapours. faster than i.v., takes 5-8 seconds.
sublingually
applied under the tongue. absorbed through membranes of mouth.
transdermal patch
device attached to the skin that slowly delivers the drug through skin absorption.
biotransformation
process of changing the molecular structure of a drug into forms that make it easier for the body to excrete it. how urinary excretion begins, mostly through enzymes in liver.
metabolite
by-product resulting from biotransformation process. structurally modified forms of original drug.
enzyme induction
repeated drug taking results in greater production of liver enzymes that metabolize that drug and similar ones.
enzyme inhibition
repeated drug taking stops the action of specific liver enzymes and metabolism of drug slows down.
drug competition
drugs taken in combination occupy all available liver enzymes leaving excess drugs nonmetabolized & resulting in toxic levels.
elimination half-life
length of time it takes for a drug to be reduced to 50% of its equilibrium level in bloodstream. (original concentration level.)
latency period
an interval of time during which blood levels of a drug are not yet sufficient for a drug effect to be observed.
cross-tolerance
phenomenon in which the tolerance that results from the chronic use of one drug induces a tolerance effect with regard to a second drug that has not been used before. (ex: alochol, barbiturates, benzos.)
cross-dependence
phenomenon in which one drug can be used to reduce the withdrawal symptoms following the discontinuance of of another drug.