13 Drug Abuse Flashcards
Common Drugs of Abuse/Recreational Use
Psychomotor stimulants
- Amphetamine (‘speed’)
- Cocaine (including ‘crack’)
Psychotomimetic agents
- Cannabis
- Lysergic acid diethylamide (LSD, ‘acid’)
Opioids
- Morphine
- Diacetylmorphine (Heroin, ‘smack’)
CNS depressants
- Ethanol
- Barbiturates (‘yellow jackets’, ‘goofballs’)
- Benzodiazepines (‘jellies’)
Health triangle - A
A. MENTAL/EMOTIONAL
INTERFERENCE WITH BRAIN FUNCTIONS
• Psychiatric co-morbidity is commonly reported – depression, anxiety, difficult concentration,
– personality and psychotic disorders
Health triangle - B
B. PHYSICAL
SLEEPINESS, IRRITABILITY, HEART FAILURE, STROKE
• Risk of blood-borne diseases – HIV
Infection from IV drug use
– Hepatitis B and C
Health triangle - C
C. SOCIAL
WITHDRAWING FROM FAMILY AND FRIENDS LOSS OF INTEREST IN SCHOOL AND OTHER ACTIVITIES
• A link between drug use and acquisitive crime
– Around 75% of the users of heroin and crack cocaine admit to committing crime to support their habit
Principle dopaminergic tracts
1. Nigrostriatal tract
Extrapyramidal pathway - begins in the substantia nigra and ends in the caudate nucleus and putamen of the basal ganglia
Principle dopaminergic tracts
2. Mesolimbic tract
Originates in the midbrain tegmentum and innervates the nucleus accumbens and adjacent limbic structures
Principle dopaminergic tracts
3. Mesocortical tract
Originates in the midbrain tegmentum and innervates anterior corticol area
Principle dopaminergic tracts
4. Tuberoinfundibular tract tract
Projects from the arcuate and periventricular nuclei of the hypothalamus to the pituitary
Role of dopamine in addiction
Low D2 receptors cause increased pleasure from abused drugs which leads to further drug abuse
Drug Addiction (dependence)
a complex disorder (disease) in the brain
• a state in which an organism functions normally only in the presence of a drug
• compulsive drug-seeking and drug-taking behaviour and an inability to control intake (addiction);
• behavior is reinforcing (rewarding or pleasurable)
• continued abuse of drugs despite negative consequences cause serious, long-term consequence
Withdrawal syndrome
There may be symptoms of withdrawal when the drug becomes unavailable
- Adaptions in brain reward system manifest as dysphoria and drug craving
- Physical/psychological adverse effects of cessation of use of the drug
- The abuser will use drug again to relieve or avoid withdrawal symptoms
Drug tolerance
Decrease in pharmacological effect with repeated use
• short term: due to depleted levels of neurotransmitters in vesicles
• long term: due to down-regulation of the receptors
Marked increase in amounts of substance to achieve intoxication or desired effect
- Cannabis (Marijuana)
Active agent : Tetrahydocannabinol (THC)
Burning marijuana results in vaporisation of THC absorption into the lungs then into blood plasma
Marijuana high:
initial stimulation (giddiness and euphoria), followed by sedation and a pleasant tranquillity;
begin within a few minutes after inhaling, and can last 2
to 3 hours after initial intoxication.
After peak levels reached, concentration falls through metabolism in liver and fat storage
Marijuana - dried and crumbled leaves, small stems, flowering tops
Sinsemilla - pollination prevented (↑ potency)
Hashish (“Solid”) -prepared from resin
Hash oil - alcoholic extract
Acute effects of cannabis
• Psychological effects
– Sensation of relaxation and wellbeing
– Sharpened sensory awareness: sound/light appear more intense – Impairment of short-term memory and simple learning
– Impairment of motor co-ordination
• Physiological effects
– Increase in heart rate: tachycardia (sensation of a pounding pulse)
– Increase of blood flow to skin: sensation of warmth – The “munchies”: increase in hunger
- Psychomotor stimulants
Amphetamine Dopamine Noradrenaline Pseudoephedrine Cocaine Atropine MDMA (ecstasy) Serotonin
Amphetamine
- Inhibit monoamine reuptake NA, DA, 5-HT
2. Release stores of NA
Cocaine
• crystalline alkaloid
• obtained from the leaves of the coca plant
• can be snorted, smoked or injected into a vein
• giving rise to a euphoric sense of happiness and increased energy
• a stimulant of the CNS and an appetite suppressant;
• Inhibition of reuptake transporters for monoamines:
DA, (enhance dopaminergic transmission) NA
5-HT;
Opioids
• u-opioid receptor agonists produce euphoria – feeling of wellbeing and contentment
– contributes to analgesic action
– opium, morphine, heroin, codeine, dilaudid
Heroin
- Desired Effects Euphoria rush
Decrease in anxiety Reduction in pain - Undesired/Long term effects Hypothermia; Nausea/vomiting;
Bone and muscle pain; Liver/kidney disease; Veins collapsing; Increase chances for stroke; Lung infections; Pulmonary complications; HIV/AIDS; Hepatitis
Opiates abuse
• Characteristic of opiates abuse/overdoes: – respiratory depression
breathing slows down, sometimes to a stop – pinpoint pupils
an important diagnostic feature in opioid poisoning – decreased level of consciousness
– hypotension and bradycardia
heart rate slows down, sometimes to a stop
blue lips, nails (due to insufficient oxygen in the blood)
• Morphine / Heroin abuse/overdoses are the most common single cause of death from drug overdose,
account for 25% of the total;
Alcohol
Alcohol is a CNS depressant
and has multiple actions on the CNS :
enhancing the inhibitory actions of GABA at the GABAA receptor;
decreasing the excitatory actions of Glutamate at NMDA receptor;
causing releasing dopamine in the nucleus accumbens; increasing serotonin concentrations in certain regions; stimulating release of endogenous opiates,
producing euphoria and pain attenuation;
• With acute alcohol intake
– an initial depression of inhibitory neurons, producing a sense of relaxation
– followed by progressive depression of all CNS functions (loss of coordination, poor judgment, slowed reflexes)
Alcohol dependence
• Recommended limits: 21 units /week for men, 14 units / week for women;
• Chronic drinking can lead to dependence and addiction to alcohol;
• Psychological dependence;
• Physiological dependence;
• Withdrawal symptoms:
shaking (tremors), anxiety, sleep problems, and nausea;
hallucinations and even seizures;
Summary
Stimulants
Stimulants
amphetamines cocaine ecstasy
Primary target - DA receptor
Main effects/transmitters - DA
Summary
Mimetic
Mimetic
cannabis LSD
Primary target - CB1 receptor 5-HT receptor
Main effects/transmitters - DA, opiates? 5-HT
