Drugs of abuse 12/19 Flashcards
drug abuse
non-medical or non-accepted recreational use of a drug
drug misuse
improper use of prescribed compounds
drug dependence/addiction
compulsive drug use,
substance dependence despite negative consequences (craving)
withdrawal syndrome
pattern of behaviors that follow discontinuation of a drug
physical dependence charecterized by
abstinence syndrome
type and intensity differ depending on drug
DSM IV substance dependent criteria:
maladaptive pattern of substance abuse leading to clinically significant impairment or distress as manifested by 3 or more of the following, occuring any time in same 12-month period
1) tolerance:
a) need for markedly increased amounts of substance to achieve intoxication OR
b) markedly diminished effect with continued use of same amount of substance
2) withdrawal:
a) characteristic withdrawal syndrome for substance OR
b) same substance (or related) is taken to relieve or avoid withdrawal symptoms
other substance dependent criteria
3) substance is taken in larger amounts or over longer period of time
4) there is significant desire or unsuccessful efforts to cut down substance
5) great deal of time is spent in activities to obtain substance
6) important social or occupational activities are given up to obtain substance
7) substance use is continued despite knowledge of harmful effects
pharmacokinetic tolerance
ability to metabolize drug increases over time
produce limited amount of tolerance
pharmacodynamic tolerance
produces large amounts of tolerance
cellular changes,changes in binding affinity, up or down regulation of receptors
behavioral tolerance
learned or conditioned
association between environmental cues with drug
can lead to overdose outside of conditioned environment
inverse tolerance (sensitization)
mechanism not understood
can persist for years
increase in effect of drug that occur with repeated use.lower doses elicit same effects
pathways of activation in cocaine and amphetamines
1) neostriatal to caudate putamen=motor stimulation and at higher doses stereotyped behaviors and convulsion
2) mesolimbic to nucleus accumbens=elevation of mood,euphoria and reward
3) mesocortical to limbic cortex=enhanced attention,alertness.At higher doses,see psychosis
amphetamines
methamphetamine,methylenedioxymethamphetamine (MDMA),fenfluramine,methylphenidate
fenfluramine
no apparent abuse liability
prolonged use of MDMA
neurotoxicity
amphetamine psychosis
panic,paranoia and repetitive behaviors
clinical uses of amphetamines
methylphenidate=ADHD
atomoxetine=ADHD,NE-reuptake inhibitor
rarely for narcolepsy and appetite suppression–> phentolamine
tolerance and dependance of methamphetamines
tolerance=euphoria+anorexia rapidly, Slowly to locomotor and stereotyped behaviors
dependence=related to unpleasant after effects and euphoria
Withdrawal=no clear syndrome
cocaine
less likely to produce psychosis
no clear-cut withdrawal,but see depression and fatigue
psychological dependence=craving
effect on CNS after chronic use can last for a long time–> CNS plasticity
half-life of cocaine
very short–> binge use
prenatal exposure to cocaine
functional deficit at birth
lower IQ,poor language
impaired cognitive functioning
impulsivity (self-regulation) and impaired attention
impaired auditory information processing and habituation
Nicotine
on nAChR in VTA,cortex and hippocampus
chronic use–> desensitization and increase in number of receptors
causes muscle relaxation and increases learning
Antagonist=mecamylamine
Tx of nicotine dependence
bupropion (wellbutrin)= NE-DA reuptake inhibitor,lowers seizure threshold,contraindicated with bipolar
varenicline (chantix)=nAChR partial agonist, prevents relapse,concerns over production of suicidal thoughts
hallucinogens
affect thought, perception and mood without causing psychomotor stimulation or depression
no tolerance or dependence
target cortical and thalamic circuits
