chapter 3 uppers. behavioral stimulants cocaine/amphetamines psychostimulants tranquilizer augment...
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CHAPTER 3 Uppers
Behavioral StimulantsCocaine/AmphetaminesPsychostimulantsTranquilizerAugment synaptic action
DopamineNorepinephrineSerotonin
Stimulate the nucleus accumbensBehavioral reinforcementCompulsive abuseAttention-deficit/hyperactivity
Behavioral StimulantsCocaine
From leaves of the plant Erythroxylon cocaOriginally chewed by natives of Central and
South AmericaMid-19th century - incorporated into many
products including wine and Coca-ColaReplaced by amphetamines – longer actingRevived when amphetamine prices rose and
‘crack’ cocaine became widespread
Behavioral StimulantsCocaine
Most users: 12-39 years old 75% male Polypharmacy Co-existing psychological problem Insufflate Alcohol dependent
Behavioral StimulantsCocaine
One of the most reinforcing/addictive of drugsHigh doseRapid onsetRapid toxicityRapid dependence
Behavioral StimulantsCocaine
Extracted from leavesGenerally produced as hydrochloride
Average dose – 25 mgCocaine base = crackCrack will volatilize allowing it to be smoked
for more rapid delivery Average dose – 250mg – 1 g
High doses of crack lead to high plasma level, and fast but short lived ‘high’
Behavioral StimulantsCocaine – Pharmacokinetics - Absorption
Absorbed from any mucous membrane, stomach, lungs
Strong vasoconstrictor, so insufflation is not very effective
Hydrochloride is MUCH less lipid soluble, so does not absorb as well as base
Smoked, onset of symptoms in seconds, lasting ~30min
Injected – 100% bioavailability
Behavioral StimulantsCocaine-Pharmacokinetics-Distribution
Freely crosses all barriersHigh lipid solubilityBrain concentrations >> plasmaFetal levels equal to maternal
Behavioral StimulantsCocaine – Phramacokinetics - Metabolism
and Excretiont1/2 of 30-90 min.Metabolized by enzymes in liver and plasma to
benzoylecgonine, ecgonine methyl ester and other inactive metabolites
Metabolized to cocaethylene in the presence of EtOH – highly toxic
Mostly eliminated in urine
Behavioral StimulantsCocaine – Mechanism of Action
Local anestheticVasoconstrictorPsychostimulant
Behavioral StimulantsCocaine – Dopaminergic Actions
Potentiates synaptic actions to dopamine, norepinephrine, serotonin due to re-uptake blockage
Dopamine reuptake blockage may be crucial to reinforcing and stimulant properties
High levels of dopamine in reward system may account for addictive/euphoric effects
Decrease discharge rate in limbic system – inhibits post-synaptic receptors
Behavioral StimulantsCocaine – Serotoninergic Actions
Studies show cocaine is a reinforcer in the absence of dopamine transporter
Serotonin may be another reinforcement mechanism
One serotonin receptor may antagonize reinforcing effects of cocaine
Behavioral StimulantsCocaine – short term, low dose
Physiological responses Increased alertness, mental activity – then depression Motor hyperactivity Tachycardia Vasoconstriction Hypertension Bronchodilation Hyperthermia Pupil dilation Increased glucose availability Increased blood flow to muscles, hyperactivity Rapid speech – incoherent Appetite suppressed
Behavioral StimulantsCocaine – short term, low dose
Psychological effects Euphoria Giddiness Enhanced self-consciousness Forceful boastfulness Euphoria/anxiety, progressing to Anxiety Promotes desire for more cocaine Tolerance quickly develops
Behavioral StimulantsCocaine
Reinforcement Strong craving for more Tolerance starts quickly leading to cyclic
dependence Rebound depression Isolation Sexual dysfunction
Behavioral StimulantsToxic effects
Huge effects on most organ systems CNS – Strokes, seizures, etc Cardiovascular – MI, Arrhythmias, cardiac arrest,
major vessel failure, etc. Pulmonary – nasal septal perforations, pulmonary
edema, bronchitis, etc GI – Ulcers, perforations, GI infarcts, etc. Kidney – failure, etc. Maternal – spontaneous abortion, placenta previa, etc. Fetal – demise, premature, defects, etc Neonatal – withdrawal, seizures, defects, etc.
Behavioral StimulantsCocaine – High Dose
HyperactivityParanoiaImpulsive, repetitive, compulsive behaviorAltered perception of realityAggressive/homicidal – persecution complexToxic paranoid psychosis
Behavioral StimulantsCocaine – Comorbidity
“virtually every psychiatric syndrome, affective disorders (mania and depression), schizophrenia-like syndromes, personality disorders and so on.”
High percentage dependent on multiple drugs
Behavioral StimulantsCocaine – Pregnancy
Crack babies Vasoconstriction - Insufficient blood flow Placental detachment Preterm labor Fetal demise Low birth weight Growth retardation Microcephaly CNS and PNS development Many congenital physical and mental defects 50,000 to 100,000 babies per year ADHD
Too diverse to specify a ‘Fetal cocaine syndrome’
Behavioral StimulantsCocaine - Pharmacological Treatment
Problems Intensity of drug effect Intensity of behavior reinforcement Relapse Co-existing disorder
Behavioral StimulantsCocaine - Pharmacological Treatment
Antiwithdrawal agents – none to dateAnticraving agents - ecopipanTreatment of comorbid disorders – difficult but
the most promisingPharmacological treatment not yet very
successful
Behavioral StimulantsCocaine – Psychosocial Interventions
Sometimes work: AA-like Individual/group counseling Cognitive-behavioral therapy Supportive-expressive therapy Behavioral reinforcement
Behavioral StimulantsAmphetamines
Sympathomimetic amines Mimic epinephrine
VasoconstrictionHypertensionTachycardiaAlerting response
Behavioral StimulantsAmphetamines
PhenylethylamineAmphetamineMethamphetamineResemble dopamine
UsesNarcolepsyADHDAppetite suppression – but…
AbuseWakefulnessAppetite suppression
Behavioral StimulantsAmphetamines
Mechanism Release norepinephrine and dopamine Dopamine stimulation of limbic system Constant repetitive behavior associated with
dopamine neurons in brain stem
Behavioral StimulantsAmphetamines
Pharmacological effects Release of norepinephrine and dopamine from
presynaptic neurons Similar response as cocaine
Behavioral StimulantsAmphetamines
Pharmacological effects Low dose (methamp more potent than amp)
Increase bp Slow pulse Relax bronchial muscles Psychomotor stimulant Increases alertness Euphoria Dexterity deteriorated Loss of appetite Wakefulness Mood elevation Alertness Feeling of power Etc.
Behavioral StimulantsAmphetamines
Pharmacological effects Moderate dose
Stimulates respiration Tremors Restlessness Greater increase in motor activity Agitation Prevent fatigue Sleep deprivation
Behavioral StimulantsAmphetamines
Pharmacological effects High dose
Continual purposelessness Repetitive behavior Aggression Violence Paranoid delusions Severe anorexia Psychosis, abnormal mental conditions Weight loss Skin sores and infections from poor hygiene/neglect
Pregnancy Little data, but some correlation to a variety of congenital
problems
Behavioral StimulantsAmphetamines
Dependence and Tolerance Potent stimulant and behavior reinforcer Typical dependence cycle use/reward/more use Withdrawal – increase appetite, weight gain,
decreased energy, increased sleep, severe depression Does not require de-tox, but other symptoms must be
closely monitored Tolerance develops quickly – binge behavior, isolation
Behavioral StimulantsAmphetamines
ICE Free base methamphetamine - smokable
Behavioral StimulantsAmphetamines
Pharmacokinetics Absorption – up to 4 hr t1/2 >11hr 60% metabolized by liver Amphetamine is primary active metabolite Excreted by kidneys
Behavioral StimulantsEffects and Toxicity
Very similar to cocainePsychomotor stimulantPositive reinforcerSelf administration difficult to controlViolent/aggressive behaviorHigh doses may lead to IRREVERSIBLE
decreases of dopamine and serotonin and a large number of serious sequelae (paranoia, schizophrenia, delusional/psychotic behavior)
Cardiac toxicity
Behavioral StimulantsOther drugs
Ritalin – amphetamine relativePemoline – non-amphetamine, lower abuse
potentialSibutramine – weight loss - similar to
amphetamines. Alternate: Orlistat – weight loss inhibits pancreatic lipase in gut. Fat not absorbed; excreted in feces
Modafinil – narcolepsy – potentiates glutamate neurotransmission
Behavioral StimulantsTreatment of ADHD
Ritalin – 90% of prescribed casesAmphetamines – similar responsePemolineBuspironeBupropionAntidepressants – nortriptyline, fluoxetine, etcLong-term efficacy of drug treatment of ADHD
unknown
CaffeineMost commonly used psychoactive drug
Coffee – caffeine - 50-150 mgTea –theophylline- 25–90 mgCola – caffeine - 25-75 mgChocolate - theobromine – 25mg/ozCocoa
CaffeineEnhanced mental alertnessIncreased energySense of well-beingDopaminergic?Reinforcing?
CaffeinePharmacokinetics
Absorption – 90 minDistribution – throughout total body waterCrosses blood-brain and maternal-placental
barriers, present at high conc in breast milkMetabolized in livert1/2 of 3.5-5 hr (extended in infants and
pregnant women)SSRIs may cause blockage of caffeine
metabolism and toxicity
CaffeinePharmacological effects
PsychostimulantRewarding effect: alertnessReduced fatigueSustained intellectual effortFine muscle control, timing, arithmetic skills
may be adversely affected’
CaffeinePharmacological effects
Heavy consumption (12 cup or more/day) Agitation Anxiety Tremors Increased respiration Insomnia Caffeinism – serious combination of the above
CaffeinePharmacological effects
Outside CNS Cardiac stimulant Hypertension Dilates coronary arteries Constricts cerebral vessels Relieves headache (migraines)
CaffeineMechanism of action
Adenosine (depressant neurotransmitter – facilitates GABA binding) antagonist
Stimulates dopaminergic activity, due to above, in cerebral cortex rather than limbic system
CaffeineReproductive effects
UnknownHigh dose may cause spontaneous abortionFDA suggests pregnant women limit caffeine
CaffeineTolerance and Dependence
HabituationToleranceWithdrawal syndrome – headache, drowsiness,
fatigue, impaired intellect, motor skills, craving
NicotinePrimary active ingredient in tobacco
4000 compounds in tobacco smokeNicotine causes pharmacologic effects, but
other compound cause most of the long-term deleterious health effects – emphysema, cancer, etc.
NicotinePharmacokinetics
Absorbed from all sites in or on bodyPeak levels reached in minutesDistribution – brain firstt1/2 about 24-120 min.Major metabolite cotinineSimilar to caffeine – some SSRIs can inhibit
metabolism leading to toxicity
NicotinePharmacological effects
BrainSpinal cordPNSHeartNausea, vomitingStimulates hypothalamus to release ADH – fluid
retentionReduces muscle toneReduces appetiteADHDPotent behavior reinforcer
NicotinePharmacological effects
Increased Psychomotor activity Cognition Sensorimotor performance Attention Memory Anxiolytic Antidepressant
Higher doses Nervousness Tremors Seizures Panic attacks
NicotineMechanism of action
Activates acetylcholine receptorsIncreased bp, pulseReleases epinephrine from adrenalsIncreases GI activityStimulates presynatptic release of dopamine,
acetylcholine, glutamateIncreases dopamine in limbic systemIncreased acetylcholine, glutamate responsible
for improved mental functions
NicotineTolerance and dependence
Does not induce biological tolerancePhysiological and psychological dependence in
most smokersNicotine is highly addictiveWithdrawal – abstinence syndrome – craving.
Irritability, increased appetite, weight gain, insomnia – can last many months
More difficult to quit smoking than stop taking many other drugs
NicotineToxicity
Most mortality/morbidity due to other compound in smoke Cardiovascular
CO – decreases O2 Nicotine – heart rate, bp, atherosclerosis, thrombosis
Pulmonary Emphysema
Cancer Nicotine probably not carcinogenic Other compounds definitely ARE carcinogenic Lung, mouth, voice box, throat, bladder, pancreas, cervical
Passive inhalation Matter of degree – all of the above
NicotinePregnancy
Spontaneous abortionFetal demisePremature delivery, early postpartum deathGrowth retardation, Low birth weightFetal hypoxia – leads to a number of
brain/behavior problemsPredisposition to addiction?
NicotineTherapy for dependence
Replacement – gum, patch, sprays, etc.All equally efficaciousAntidepressantsAbout 10-30% of those who try to quit can
make it a year.
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