Chapter 3: How we adapt to drugs- tolerance, sensitization and expectation Flashcards
Acute Tolerance?
tolerance after a single dose!A drugs effect can be greater at a specific bl during absorption than at the same bl during elimination!
ex: alcohol.
* *drug effect peaks b4 bl does**
Tolerance?
decreased effectiveness (or potency) of a drug from repeated exposure or as the need to increase dosage to acquire the same amount of effectiveness after repeated exposure. Tolerance to different effects may occur at differing rates or not at all.
Cross Tolerance?
when the tolerance to one drug diminishes the effect of another ( usually happens with drugs in the same class)
Pharmacokinetics Tolerance?
an increase of the rate the body can metabolize a drug, less molecules of drug reach action sites. via enzyme induction (increase). All effects of the drug diminish.
Pharmacodynamic Tolerance? ie compensatory tolerance!
tolerance via adjustments made by the body to compensate for the effect of a drug. ie: homeostasis bring certain body processes back to their set point when environment condition changes.
Functional Disturbances - Poulos and Cappell (1991)
Tolerance only develops in a circumstance where a drug places a demand on homeostatic mechanisms.
ex: drug makes you anorexic with the presence of food ( homeostasis adjusts)
Drug makes you anorexic not in the presence of food ( homeostasis does not adjust because there is no real change)
Behavioural Tolerance?
through expectation with a drug, an organism can learn to decrease the effect it is having on them. (via operant conditioning or classical)
Withdrawal ?
physiological changes that occur when the drug is stopped or dosages decrease.
echoes basically of left over homeostasis adjustments.
antagonists can cause them to come about in minutes but usually they occur hours after the drug is stopped.
Dependence ?
a state in which withdrawal will occur when drug use is stopped!
Addiction?
compulsively taking drugs
Opponent Process Theory? Solomon and Corbit (1974)
Abused drugs stimulate an A process that creates a euphoric state but soon after a compensatory B process creates a dysphoric state.
The more a drug is taken, process B increases and process A virtually disappears.. (increased tolerance)
Placebo Effect (expectancy): Expectancy Mechanism Colloca and Benedetti (1995)
A top-down pain relieving pathway from the cortex to a pain control center in the lower part of the brain is capable of blocking pain. when a person believes they are being given a drug this is activated.(enhances placebo response)
Factors that modify the placebo effect in medical treatment?
strength of expectation
desire for an effective treatment
motivation to avoid pain and other symptoms
(importance of double blind! ensures the same expectations and motives etc)
Nocebo Effect?
placebo generates side effects
Self- Administration
Hemby, Koves, Smith and Dworkin (1997)
drugs have different effects when self-administration is done vs laboratory administration.
dopamine is higher in those that self administer meds.