Theme 2: How drug effects change over time Flashcards
drug tolerance
the decreased effectiveness (or potency) or a drug that results from repeated admin.; or the necessity of increasing doses in order to maintain its effectiveness after repeated admin.
we develop tolerance to drug ___ at different rates
effects
we should think of tolerance to the ____ not to the ___ itself
drug effect; drug
acute tolerance
tolerance developed during a single admin; drug effect may be great during the absorption phase as compared to the elimination phase even if it’s the same blood level; on a graph, the drug effect curve is shifted left from the blood level curve
cross-tolerance
tolerance to one drug diminishing the effect of another drug (Eg. different opioids)
pharmacokinetic/ metabolic tolerance
an increase in the rate or ability of the body to metabolize a drug, resulting in fewer drug molecules reaching their sites of action; mostly enzyme induction (more of the enzyme that destroys the drug); tolerance for all effects because the drug concentration is diminished; cross-tolerance with drugs that may be metabolized by the same enzyme
cellular or pharmacodynamic tolerance
rises from adjustments made by the body to compensate for an effect of the continued presence of a drug (to maintain homeostasis); compensatory processes
upregulation
if a drug block a receptor, cellular tolerance may be developed by creating more receptors
for tolerance to occur, the drug effect needs to have ….
some significance to the animal/ disruption to functioning; drug effect puts a demand on an organism’s homeostatic mechanisms
behavioural tolerance
through experience with a drug, an organism can learn to decrease the effect that the drug is having.
withdrawal symptoms
physiological changes that occur when the use of a drug is stopped or the dosage is decreased
dependence
a state in which withdrawal symptoms will occur when the drug use stops; does not imply anything about compulsive drug use, abuse, or addiction
withdrawal symptoms are often expressions of the _____
compensatory adjustments (mechanisms)
withdrawal symptoms from a single admin is process _ without any process _
B; A (also known as a hangover)
how can opponent process theory explain acute tolerance?
during the absorption phase, process B hasn’t kicked in so the drug effect is strong; during the excretion phase, process B is full blown, which lowers the impact of process A, causing reduced feeling of drug effect (explains difference in drug effect at two points of same blood level)
withdrawal is worse after prolonged drug use because…
compensatory response builds up
prolonged use causes process B to get ____ and kick in ____
strong; sooner
what is the compensatory response to a tranquilizer
anxiety
is there a strong correlation between tolerance and withdrawal?
no; many people show high tolerance but no withdrawal symptoms (eg. alcohol)
what are some reasons someone with tolerance may not experience withdrawal?
(1) may be a behavioural tolerance, so there wouldn’t be physiological compensatory responses, (2) rate of elimination may be very slow (ie. THC); allows for body to adjust
conditioned compensatory response
the conditioned drug effect will also be opposite (B) to the initial drug effect (A)
if a rat is given saline and a paw lick test in an environment that is associated with repeated injections of morphine, what will be the response? why?
even shorter latencies/ hyperalgesia; conditioned compensatory response
classicaly conditioned withdrawal
if placed in room associated with repeated drug admin. but no drug is given, compensatory processes kick in causing withdrawal effects… dangerous because it may lead to relapse if a user goes back to the place of frequent admin. (cause cravings)
operant conditioning of drug effects
learning to compensate for drug effects in order to obtain rewards (eg. waiting to respond on DRL schedule while on amphetamine)
sensitization/ reverse tolerance
effect of a drug increasing with repeated admin. (much less common than tolerance)
what brain system gets sensitized?
mesolimbic dopamine system
expectation mechanism
a top-down pain-relieving pathway activated by the expectation of such drugs
predisposition theories
people either are born with the disease or acquire it at some time before they begin abusing the drug. This disease predisposes certain people to become addicts whenever they start using the drug
exposure theories
addiction is a disease that is caused by repeated exposure to the drug
types of disease theories
predisposition and exposure
is addiction a disease?
depends how you define disease
using to avoid withdrawal symptoms is what type of operant conditioning?
negative reinforcement
dependence model
dependence is the state in which a drug produces physiological dependence (withdrawal if stopped) AND compulsive self-admin
belief that withdrawal symptoms are so painful and distressing that dependent individuals are willing to sacrifice almost anything to avoid having to go through withdrawal and that addicts crave the drug because it will prevent the withdrawal.
problem with the dependence model
it is possible to have an addiction in the absence of dependence (eg. weed or cocaine which have little withdrawal and therefore little power to cause dependence) and to have dependence without addiction (eg. depend on pain pain relievers but not show addictive beh)
Factors That Alter the Reinforcing Value of a Drug
(1) different drugs, (2) dose of drug, (3) breeding and strain differences, (4) relief of unpleasant symptoms, (5) task demands, (6) stress, (7) deprivations and motivations, (8) previous experience with other drugs, (9) previous experience with the same drug, (10) withdrawal symptoms, (11) extended access, (12) priming or reinstatement, (13) conditioned reinforcement, (14) second-order schedules
incentive
this attraction to a specific stimulus
mesolimbic dopamine system
VTA -> nucleus accumbens
reinforcement, motivation and reward seeking
the nucleus accumbens usually inhibits the motor system, unless…
DA is released; inhibits the inhibitory (aka activates)
stimuli associated with reinforcement are said to have acquired _____
incentive salience
