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Antidepressants and Stimulants
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Depression
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What is REALDepression ?
Apathy, low self esteem, insomnia, personal neglect, loss
of appetite, loss of libido, pessimism, lack of motivation
NOT thought disturbances
Types ofDepression
Exogenous Depression: Associated with a life crisis event
Endogenous Depression: Not associated with any trigger
Depressive Syndromes : Unipolar and Bipolar AffectiveDisorder
(more on these later)
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Pathophysiology ofDepression
Monoamine Theory ofDepression
1960s proposed that depression was caused by reduced levels of
monoamines in the brain
Important monoamines being Noradrenaline and Serotonin
Antidepressant Drugs increase Noradrenaline and Serotonin levels
in the CNS
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Noradrenaline and 5-HT in the CNS
Arousal and Mood(also BR, HR)
Behaviour, Sleep, Mood, Food Intake
Body Temp,
NA 5-HT
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Monoamine Nerves: Neurotransmission
Action potential
Release of neurotransmitter (NA or 5-HT)Acts on specific receptors (for NA or 5-HT)
Excess transmitter release inhibited by presynaptic receptors (NA via E2)
Neurotransmitter removed from synapse by amine uptake pump
Excess neurotransmitter in presynaptic neuron degraded by Monoamine
oxidase (MAO)
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Sites of Action for Anti-Depressants
5-HT re-uptake inhibitors
Monoamine (NA and 5-HT) re-uptake pump inhibitors
Blockade of pre-synaptic E2 receptors
Inhibition of MAO enzyme
5-HTreuptake
and
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5-HT Reuptake Inhibitors
Now the most prescribed anti-depressant
Specifically block the re-uptake of 5-HT by the presynaptic neuron
Results in increased 5-HT in the synapse
Not many Side Effects (compared to tricyclics)
eg. Fluoxetine (Prozac)5-HT reuptake
inhibitor
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Tricyclic Antidepressants (TCA)
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Tricyclic Antidepressants (TCA)
Block the amine reuptake pump
Block the reuptake of 5-HT AND Noradrenaline
More effective than 5-HT reuptake inhibitors in severe depression
Side EffectsAnti Muscarinic p dry mouth, urine retention, constipation, blurredvisionAntihistamine p sedation
Antiadrenergicp
postural hypotension
Contraindicated in people with cardio problems (infarction, arrhythmias)and Epilepsy
eg. Imipramine
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Tetracyclic Antidepressants
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Tetracyclic Antidepressants
Block presynaptic E2 receptors
Increase Noradrenaline levels in synapse
Also block reuptake NA and to lesser extant 5-HT
Also blocks some 5-HT receptors
Side EffectsAntihistamine:Drowsiness
eg. Mianserin
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Monoamine Oxidase Inhibitors (MAOI)
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Monoamine Oxidase Inhibitors (MAOI)
Breaks down monoamines (NA,Dopamine, 5-HT)
Increased levels of NA 5-HT in presynaptic neuron; more for release
Enzyme within the mitochondria of presynaptic nerve
Block MAO
MAO in the gut and breaks down tyramine
So what you ask
Two forms of MAO. MAOA and MAOB
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Monoamine Oxidase Inhibitors (MAOI)
Excess tyramine (amino acid) in circulation causes the release ofnoradrenaline from sympathetic nerves
Increased BP, increased HR, increased SV
People taking MAOIs for depression should avoid foods rich in tyramine
(Beer, wine,hot dogs, beans, sour cream)
MAOIs are contraindicated in people with CV disease,hepatic
disease, epilepsy. People taking sympathomimetics, levodopa
MAOI inhibitor eg. Phenelzine
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Monoamine Oxidase Inhibitors (MAOI)
Newer MAOIs are specific for MAOA.
MAOA is involved in controlling NA and 5-HT levels in
depression pathways
Still have to be careful with tyramine consumption in diet
Less Side Effects
Dont work as well
eg. Moclobemide
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5-HT and
NA reuptake
inhibitor
Noradrenaline-Serotonin Reuptake Inhibitors
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Noradrenaline-Serotonin Reuptake Inhibitors
New class of antidepressants
Work similar to Tricyclic Antidepressants BUT dont have
antihistamine, antiadrenergic, anticholinergic effects
May be more effective than 5-HT reuptake inhibitors
eg. Venlafaxine
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CNS Stimulants
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CNS Stimulants
Used forWeight Loss (Anorectics)
Attention Deficit Disorder
Attention Deficit HyperactivityDisorder
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Anorectics
Why stimulants for weight loss ?
Most are sympathomimetics
(mimick sympathetic nervous system)
Restless euphoric sense of well being talkative increased libido
Forget about food
InsomniaRebound
Depression
Side Effects
eg. Phentermine
CNS Effects
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ADD and ADHD
Neurochemical imbalance ??
Mainly affects children
Obsessiveness, forgetfulness, frustration,
daydreaming, aggressiveness, uncooperative
+ in ADHDhyperactive as well
Controversial in terms of its diagnosis and treatment
It is ironic that ADDADHD patients respond to CNS stimulants
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ADD and ADHD
ADD and ADHD treated with CNS stimulants
eg. Methylphenidate (Ritalin) and Dexamphetamine
Increase monamines (NA and 5-HT) in CNS
Reduction in appetite, euphoria, insomnia
Side Effects: headache,hypertension, growth retardation, palpatations
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Drugs to know
Antidepressants
Fluoxetine
Imipramine
Mianserin
Phenelzine
Moclobemide
Venlafaxine
CNS Stimulants
Phentermine
MethylphenidateDexamphetamine
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