Chapter 6 - Psychostimulants Flashcards
What do sympathomimetics do?
increase sympathetic NS activity; inc motor activity; improve alertness; elevate mood
ex. amphetamine, methamphetamine; cocaine
medical vs non medical purposes of sympathomimetics
decongestant, ADHD, narcolepsy VS meth, crack, cocaine
First natural amphetamines were derived from ____ and was used as ____
Ephedra (ephedra sinica); cough suppressant (16th century China) and was a precursor for the illicit manufacture of methamphetamine
Amphetamine was developed by ____ and was used to ____
German chemists in 1887; inc BP (20s), treat adhd (30s) and in WWII
Two optical isomer forms of amphetamines
d-amphetamines and l-amphetamines; d is more potent
Racemic mixtures of amphetamines
contains both d- and l- isomers
ex. adderall contains 3:1 of d- to l-
-mostly used for narcolepsy and ADHD; less military use
Methamphetamine was developed by ____ and is mainly used ____
a JPN chemist in 1919; illicitly (notorious drug of abuse) but was recently approved by FDA as treatment for ADHD (Desoxyn)
Methylphenidate
relatively weaker psychostim; discovered in 1944 (Ritaline); prescribed to more than 2/3 US kids with ADHD
Cathinones
bath salts (new drugs, 90s); synthetic cathinone compounds
what is cocaine?
derived from Erythroxylon coca; salt/powder form is called cocaine hydrochloride
-crack cocaine is formed when hydrochloride is freed from base with baking soda
For therapeutic effects, psychostimulants are usually administered ____
orally (pills); however methylphenidate sometimes liquid and skin patch form
Why do users (for rewarding effects/illicit use) prefer intravenous injection/insufflation/inhalation?
these routes guarantee rapid absorption
inhalation: 1.4min
IV: 3.1min
Insufflation: 14.6min
The ____, the more likely is it for addiction to occur
quicker the route of administration
There are active metabolites for ___, ____, and ____
mathamphetamine, cathinone, and cocaine
-often have similar effects as original drug
____ use can also result in stronger active metabolites
polydrug
ex. cocaine and alcohol produces the metabolite cocaethylene which has greater rewarding properties than either drug alone
half lives of psychosimulants
methamphetamine = 11 hours
amphetamine = 10 hours
methylphenidate – 2.5 hours
cathinone = 1.5 hours
cocaine = 1 hour
amphetamine and methamphetamine increases DA levels in the synapse by 1. ____ and 2. ____
- reversing the direction of DA transporters found on the presynaptic cell
- displacing DA from synaptic vesicles which allows more DA to be released through the reversed transporters
pharmacodynamics of methylphenidate and cathinones
similar to amphetamine and methamphetamine; inc levels of monoamines DA, 5HT, NE; less efficacy than amphetamine
Does cocaine block dopamine reuptake?
yes (of all monoamines incl DA); incr the movement of DA into synaptic vesicles so that there is more DA stored for future release
at a sufficiently high dose, cocaine can act as a ____ which explaines why it can act as a ____
Na+ channel; local anesthetic
DA levels in the ____ are important for reinforcing the properties of ____
nucleus accumbens; psychostimulant drugs
What is CART?
Cocaine- and Amphetamine- Regulated Transcript; a peptide NT produced with use of psychostimulants; synthesized and stored in mesolimbic and tuberinfundibular DA pathways
BY ITSELF, CART ___ DA and acts as a ____
increases; psychostimulant
When CART is given in combination with a psychostimulant, it ____
reduces the effect of a psychostimulant
What system do psychostimulant drugs produce most of their effects on?
Sympathetic NS (vasoconstriction, pupil dilation, etc)
-can also act an an anorectic
How do low doses of psychostimulants effect behaviour?
increases purposeful behaviour; effects are dependent on pre drug rates; incr low baseline behaviour activity BUT decr high rates of baseline behaviour activity (thats why it can treat ADHD)
How do high doses of psychostimulants effect behaviour?
increases purposeless behaviour
-produces stereotypies in rats: repetitive grooming, head swaying, licking, etc
-produces punding in humans: repetitive teeth grinding, tapping, skin picking, nail biting
Subjective effects of low doses
increased alertness, energy, well-being, enthusiasm; used to treat narcolepsy
Subjective effects of high doses
produces a “rush” and euphoria (very rewarding effect) especially with rapid absorption
Tolerance of drugs
more pronounced for reinforcing effects of the drug (less high); occurs more often with continuous drug use
Sensitization to drugs
cravings may become more powerful as the incentive value of drug-related stimuli increases; increase in purposeless behaviours; associated with intermitted drug use
Cardiovascular effects (adverse effects of psychostimulant use)
enhanced sympathetic NS activation, constricts blood vessels and increases HR
-hypertension, stroke, aortic rupture, heart attack
Abnormal fetal development (adverse effects of psychostimulant use)
blood vessel constriction, blood flow to fetus is reduced, limited O2 and nutrient delivery
Pulmonary dysfunction (adverse effects of psychostimulant use)
injury during inhalation; hemorrhaging; edema; tissue inflamation
diseases associated with IV use (adverse effects of psychostimulant use)
HIV, HEP, TB
Meth mouth (adverse effects of psychostimulant use)
toothy decay; caused by poor dental hygiene, damage to gums, decreased salivation
psychostimulant-induced psychosis (adverse effects of psychostimulant use)
similar to schizophrenia (paranoia, delusions, agitation); tactile hallucinations (formication); sometimes visual hallucinations
psychostimulant withdrawal
primarily occurs from psychological dependence rather than physical dependence
-psychostimulants produce incr in activity/enjoyment/euphoria, withdrawal can produce lethargy, lack of joy (anhedonia), and dysphoria
Women may be more vulnerable to addiction because…
starting earlier in life; more likely to binge; develop dependence quicker; may be related to sex hormones or stress
Disulfiram - Antabuse (treatments for psychostimulant addiction)
often used for treating alcoholism (inhibits aldehyde dehydrogenase); prevents DA conversion to NE (increases aversive effects)
Modafil - Provigil (treatments for psychostimulant addiction)
substitution therapy (has mild psychostimulant effects); often used to treat narcolepsy
Tricyclic antidepressants (treatments for psychostimulant addiction)
reduce cravings and depression
Anticonvulsant drugs (treatments for psychostimulant addiction)
increases GABA; reduces conditioned responses to drugs; thought to block learned associations (weakens incentive salience)
Psychostimulants as cognitive enhancers (college students)
college students have been used to improve memory, cognition, or concentration; illicit drug use since drug was not prescribed to them
Psychostimulants elevate DA in ____ and could increase ____
prefrontal cortex; working memory
-psychostims enhance motivation for engaging in novel stimuli or experiences
What is ADHD?
disorder characterized by attention deficits and/or hyperactivity and inability to control impulsive behaviours
Psychostimulants treat ADHD through its ____
rate-dependent effects
-decrease high rates of baseline behavioural activity
