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What is the difference between pharmacology, neuropharmacology and psychopharmacology
- Pharmacology is the study of the action of drugs, and their effect on living organisms
- Neuropharmacology looks at drug-induced changes in neurones at the physiological, receptor, biochemical, and molecular levels
- Psychopharmacology on the other hand looks at the effects this has on one's cognitions, behaviour and mood
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What is the effect of a drug dependent on?
The concentration of the drug, and the sensitivity of target mechanisms
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What is the dose response curve?
- The effectiveness of a drug plotted against the dose used
- This usually reaches a plateau where no further increase in dosage yields an increase in response
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What is the margin of safety?
- The difference in dose that is required in order to prevent drugs with more than one effect from having dangerous side effects
- For example, if a drug caused anxiety reduction at 1mg, but respiratory problems at 5, then the margin of safety is 4mg
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What is an agonist?
- A drug that increases the effect of a neurotransmitter by:
- Increasing production or storage of neurotransmitter,
- Increasing release of neurotransmitter,
- Stopping neurotransmitter being cleared from synapse, or
- Binding to post-synaptic receptors and activating them
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What is an antagonist?
- A drug that decreases the effect of a neurotransmitter by:
- Decreasing production or storage of neurotransmitter,
- Decreasing release of neurotransmitter, or
- Binding to post-synaptic receptors and deactivating them
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What is this the pathway for?
Dopamine
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What is this the pathway for?
Noradrenaline
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What is this the pathway for?
Serotonin
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What is this the pathway for?
Acetylcholine
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Why does atropine make pupils dilate, and why does curare paralyse?
- Acetylcholine is a neurotransmitter for the parasympathetic nervous system, and also handles nerve to muscle transmissions
- Both these drugs block Ach receptors
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What does noradrenaline handle?
- Major transmitter for the sympathetic nervous system (increases blood pressure etc)
- Besides arousal and vigilance, brain noradrenaline systems are involved in sexual behaviour and appetite
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What are the medical implications for dopamine degeneration, and the effect of drugs on them?
- Degeneration of nigral dopamine neurones is the basis of Parkinson’s
- Cocaine, amphetamines block re-uptake of dopamine, among other effects
- Chlorpromazine is an antagonist of some dopamine receptors, and is one treatment for schizophrenia symptoms, though why remains unclear
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What is DBS?
- Deep brain stimulation
- For treatment of Parkinsons, requires high frequency stimulation of pedunculopontine nucleus, but how it works remains unclear, though it certainly reduces symptoms. More than 30,000 people now implanted worldwide
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What is the relationship between drugs and serotonin?
- LSD is an agonist of serotonin receptors, and MDMA (‘ecstasy’) increases the amount of serotonin in synapses.
- MDMA originally developed as an appetite inhibitor (hypothalamus) and then as tool in marriage therapy
- Selective serotonin reuptake inhibitors (SSRIs) common as anti-depressants
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What is Ketamine?
- Mild form of PCP
- An antagonist of NMDA receptors
- NMDA receptors are glutamate receptors that are widely distributed in the brain, generally post-synaptic,but maybe also pre-synaptic
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What does Ketamine do?
- Blocking NMDA receptors with ketamine:
- Reduces pain transmission in the spinal cord
- Increases heart activity and blood pressure, by increasing the brain’s output to the sympathetic nervous system
- Changes the EEG - alpha wave decreased, slow rhythms increased
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