Drugs Of Abuse

Question 1

Definition of dependence

Answer 1

Psychological and physical phenomena associated with drug use

Question 2

Tolerance definition

Answer 2

Deceased effect or increased dose needed to produce same effect

Question 3

Withdrawal definition

Answer 3

Signs and symptoms associated with reduced drug intake or withdrawal

Question 4

Addiction definition

Answer 4

Compulsive relapsing drug use despite negative consequences, triggered by cravings in response to contextual cues

Question 5

What does dopamine play a role in

Answer 5

Movement, motivation, reward and addiction

Question 6

Dopamine pathway involved in addiction

Answer 6

Mesolimbic dopamine system

Question 7

Process of reinforcement

Answer 7

Dopamine-producing projections from the ventral tegmental area extend to prefrontal cortex and limbic system
Limbic system contains nucleus accumbens , hippocampus and amygdala
Limbic system components have D2 sites - stimulated by drug and cause cravings for drugs to replenish dopamine . Receptors likely reduce in number due to repeated over stimulation

Question 8

Addiction and dopamine interaction

Answer 8

Drugs directly or indirectly increase dopamine in pleasure and motivation pathways –> change normal communications between neurons
Addictive drugs increase dopamine –> strong but inappropriate learning signal -> hijack reward system -> pathological reinforcement with automatic compulsive behaviors

Question 9

Definition of intoxication

Answer 9

Transient syndrome following recent substance ingestion with physical and psychological impairment

Question 10

3 classes of activity at ventral tegmental area

Answer 10

Class I and II at VTA alone, class III at VTA and NA
Class I: opioids, THC, GHB - at G(io) protein-coupled receptors 
Class II: BDZs, nicotine, ethanol - at ionotropic receptor/ ion channel
Class III: cocaine, amphetamines , ecstasy - at dopamine transporter

Question 11

Effects of dopamine, norepinephrine and serotonin

Answer 11

DA and NE have sympathomimetic effects

Serotonin has hallucinogenic effect. Normal functions include mood, memory, sleep and cognition

Question 12

Commonly abused opioids and site of action

Answer 12

Morphine, heroin, codeine

Interact with u-receptor -> inhibits GABA neurons -> euphoria

Question 13

Features of opioid withdrawal

Answer 13

Nausea and vomiting
Muscle aches
Rhinorrhoea 
Lacrimation
Piloerection
Sweating
Diarrhea

Question 14

Management of opioid overdose and addiction

Answer 14

Naloxone - competitive opioid antagonist -> reverses effects of drug in minutes
Naltrexone - longer duration of action than naloxone, better for LT mx, can also be used in alcohol dependence
Long acting = methadone - substitute for shorter acting, more rewarding opioids; abrupt termination can lead to severe withdrawal
BDZs and loperamide

Question 15

Effects of exogenous THC

Answer 15

Psychoactive agent with dose-dependent perceptual changes
Presynaptic inhibition of GABA neurons in VTA-> disinhibition of dopamine neurons -> euphoria and relaxation
Half life 4 hours, onset within minutes and max effect 1-2 hours later

Question 16

Medical uses of marijuana

Answer 16

Increase appetite

Relief of chronic pain

Question 17

Features of marijuana withdrawal

Answer 17

Restlessness
Agitation
Irritability
Insomnia
Nausea 
Cramping

Question 18

Management of marijuana withdrawal

Answer 18

BDZs - anxiety and restlessness

Symptomatic relief

Question 19

Function of endocannabinoids

Answer 19

Regulate pain, appetite, memory and mood

Question 20

Mechanism of cocaine intoxication

Answer 20

Blocks uptake of DA, NE and 5HT through transporters

Blocks DA transporter –> increased DA in NA-> rewarding effects

Question 21

Clinical effects of cocaine intoxication

Answer 21

Decreased appetite
Hyperactive
Sleep disturbance

Question 22

Cocaine intoxication is associated with increased risk of

Answer 22

ICH
Ischemic stroke
MI
Seizures
Ventricular arrhythmias

Question 23

Mechanism of amphetamines

Answer 23

Synthetic indirect-acting sympathomimetics -> release of endogenous biogenic amines, DA and NE

Question 24

Effect of amphetamines at cellular level

Answer 24

Interferes with vesicular monoamine transporter
Depletes synaptic vesicles of NT content
Increased DA and other amines in the cytoplasm

Question 25

Clinical effects of amphetamines

Answer 25

Similar to cocaine

Euphoric to a lesser extent but longer lasting

Question 26

Presentation of opioid intoxication

Answer 26

Reduced consciousness preceded by euphoria
Constipation
Pupillary miosis
Conjunctival injection

Question 27

Presentation of marijuana intoxication

Answer 27

Agitated
Perceptual disturbances
Psychotic features
Auditory hallucinations

Question 28

Presentation of alcohol intoxication

Answer 28

Euphoria 
Social disinhibition
Difficulty with balance and muscle coordination
Vomiting
Comatose

Question 29

Presentation of cocaine or tik intoxication

Answer 29

Sinus tachycardia
Hypertension
Hyperthermia
Mania
Agitation
Delusional

Question 30

Effect of alcohol on neurotransmitters

Answer 30

GABA - increases inhibitory transmission at GABA-A receptor acutely; chorionic consumption causes suppression of GABA activity (=tolerance)
Glutamate - decreases excitatory transmission at glutamate receptor ; brain attempts to restore equilibrium -> increases glutamate -> when alcohol stopped, inhibition stopped, enter into hyper-excitable state

Question 31

Features of alcohol withdrawal / DTs

Answer 31

ANS hyperactivity 
Hand tremor
Nausea and vomiting
Insomnia
Transient hallucinations or illusions
Psychomotor agitation
GTC seizures
Anxiety

Question 32

Management of DTs

Answer 32

Goals- decrease immediate withdrawal symptoms; prevent complications ; LT mx to promote alcohol abstinence
Meds- BDZs; carbamazepine; B-blocker