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33 Cards in this Set
- Front
- Back
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Why are drugs abused? |
1) Rewarding effect of the psychoactive drug (positive reinforcement, psychological dependence).
2) Habituation or adaptation (rely on drug to feel well) |
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Which areas are important in drug abuse and addiction? |
NAc (nucleus accumbens) and VP (Ventral palladium) involved in reward/salience. Other pathways involved in motivation/learning/memory/inhibition control |
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What are the key transmitters modulating dopaminergic transmission? |
Drugs of dependence increase dopamine in the nucleus accumbens. ACh Serotonin NA GABA Glutamate Opioids |
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How does amphetamine work? |
CNS stimulant. Releases DA, 5HT and NA in CNS |
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What are the effects of amphetamines? |
Effects vary with mood, personality and environment: -mood elevation, euphoria -increase locomotor activity -stereotypic behaviour
Physical and mental performance improved? Fatigue postponed, confidence, speedy performance but less accuracy. |
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What are the effects of amphetamine overdose? |
-Anxiety, nervous and physical tension -Tremors, confusion, dizziness, time passes quickly -Hyperthermia, tachycardia, increased blood pressure, vascular collapse -> death. -Amphetamine psychosis --> hallucinations. |
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Why do amphetamines cause dependence? |
Related to dopaminergic actions in nucleus accumbens (particularly addictive in depressives, lonely people i.e. those with lower base level DA).
Withdrawal leads to lethargy, sleep, desire for food, depression. |
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How do amphetamines suppress appetite? |
5HT effect |
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What is MDMA and what is its MoA? |
Ecstasy.
Releases dopamine and serotonin (more than NA). Less effective than amphetamine/LSD. Feeling of closeness, empathy, love and heightened self awareness. |
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What are the side effects of MDMA? |
-Psychological dependence -Increase HR and BP -Disrupted thermoregulation (chills/sweating) -Potential degeneration of 5HT and DA neurons as some metabolites are ROS (affects mood, memory, sleep and appetite). |
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What is LSD and what are its effects? |
Lysergic acid diethyl amide; hallucinogen.
Visual, auditory and tactile hallucination: sensory modalities confused. Thought processes disturbed but aware drug-induced.
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How does LSD cause dependence and tolerance? |
Dependence: doesn't really. Experience usually aversive rather than reinforce.
Tolerance: need to increase dose to get same effect. Phamacodynamic tolerance --> cross tolerance with other psychotomimetics. |
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What is the MoA of LSD? |
Agonist at 5HT receptors
Activates auto receptors on 5HT neurones in Raphe. |
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What is the MoA of caffeine and which drug class does it belong to? |
Drug class = methylxanthine. -Adenosine antagonist, phosphodiesterase inhibitor (decrease cAMP breakdown). -Affects transmission beyond NA, DA and 5HT (some influence on these through PDE effects) |
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What are the effects of caffeine? |
Stimulates mental activity: postpones boredom, fatigue, inattentiveness. Enhance intellectual/motor performance (if reduced by fatigue/boredom).
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What is delta 9 THC and its effects? |
`Marijuana. Depressant (inhibits inhibition)
Subjective effects: influenced by characteristics of drug and people. Sharpened sensory awareness, increased intensity of sounds and sights.
Relaxation, feeling of well being (like alcohol but without aggression). |
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What is the MoA of marijuana? |
Cannabinoid receptors activated by endogenous ananadamide. GPCRS -> inhibition of adenylate cycles (inhibition of transmission).
CB1(central): impaired STM, motor cooridnation, catalepsy, anti-emetic, analgesia, increased appetite.
CB2 (peripheral): tachycardia, vasodilation, reduced intraocular pressure, bronchodilation. |
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What are the effects of ethanol? |
Behavioural effects: subjective. -increased self confidence, euphoria -at higher doses -> increased aggression Motor effects: -loss of motor coordination; slurred speech Tissue effects: -CV protection of red wine? -Liver damage, neurodegeneration, foetal impairment |
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What is the MoA of ethanol? |
CNS depressant: can variously
-inhibit Ca2+ channel opening. -enhance GABA action (GABAa receptors) -inhibit glutamate receptos (N-methyl-D-aspartate type channel) |
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Does ethanol cause dependence and tolerance? |
Marked tolerance: pharmacokinetic due to increased clearance (expression of liver enzymes) Physical dependence: well defined abstinence syndrome. Behavioural (anxiety, insomnia, dizziness); neurological signs (tremor, agitation, convulsions); other (anorexia, vomiting, sweating).
i.e. dependence not always to feel good - drink to stop feeling bad. |
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What are the antidepressant classes? |
-1st generation: TCAs, MAo inhibitors -2nd generation: SSRIs, SSNRI -3rd generation: novel monoaminergic drugs, non-monoaminergic drugs |
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What is the MoA of TCAs? |
Inhibits neuronal uptake of NA and serotonin.
Antagonises a-adrenoceptors, muscarinic receptors, histamine receptors and serotonin receptors.
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What are the clinical effects of TCAs? |
Takes weeks to develop despite pharmacological effects manifesting in hours. Adaptive changes likely underly antidepressant activity.
Narrow "therapeutic window"
SEs: gradual accumulation possible, sedation, anticholinergic, postural hypotension, weight gain. Confusion, mania, dysrhythmias. |
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What are MAO inhibitors? |
Increase levels of 5-HT, NA and DA Delayed antidepressant effects •Irreversible: phenelzine, tranylcypromine -“Cheese reaction” - not well tolerated Foods containing tyramine can precipate hypertensive crisis: Cheese, red wine, chocolate, bananas •Reversible: Moclobemide MAO A selective less likely to cause ”cheese reaction“ Side effects Postural hypotension, dizziness, nausea, insomnia |
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What is phenlzine? |
Irreversible MAO inhibitor
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What is Moclobemide? |
Reversible MAO inhibitor |
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What is tranylcypromine |
Irreversible MAO inhibitor |
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What are SSRIs? |
Selective for 5HT uptake. Few adrenergic, cholinergic, histaminergic actions.
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What are the side effects of SSRIs? |
Nausea, insomnia, agitation, weight change, loss of libido.
Generally high TI unless combined with other drugs (i.e. MAO and TCA -> serotonin syndrome. Muscle rigidity, CV collapse). |
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Fluoxetine? |
SSRI |
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Paroxetine |
SSRI |
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Sertraline |
SSRI |
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Venlaflaxine? |
SSRI and NA uptake inhibitor. Minimal doapmine effects Minimal receptor effects. |
