Anti Depressants Flashcards
Types of Antidepressant drugs
TCAs MAOI SSRI Lithium Electroconvulsive
What are the two classes of psychoses
Schizophrenia and affective disorders
Whats are the two classes of affective disorder
Mania and Depression
Symptoms of Depression
(emotional) Misery/Pessimism Low Self-esteem Loss of Motivation Anhedonia (biological) Slowing of thought & action Loss of Libido Loss of Appetite
Describe Reactive Depression
Unipolar, relatively late onset, caused by stressful life events, non-familial
Describe endogenous Depression
Unipolar, unrelated to external stress, shows familial pattern
Describe bipolar depression
Oscillating depression, less common, early adult onset, strong hereditary tendency, drug treatment Lithium
Monoamine Theory of Depression
Depression is a functional deficit of monoamines, mania is a functional excess
How does reserpine act to reduce mania
inhibits NA and 5-HT (serotonin) storage
How does ECT work
Increases CNS response to NA and 5-HT
How is cocaine an exception to the Monoamine Theory
Cocaine reduces NA re-uptake in the synapse, but has no anti-depressive effects
What is a biochemical inconsisteny with the monoamine theory?
reduction in monoamine metabolites in the urine in and delay of onset for treatment
How do TCAs work eg Amitriptyline
Neuronal monoamine re-uptake inhibitors. Actions on NA and 5-HT is equal. Act on a2, histamine and mAChR receptors.Causes delayed down-regulation of b-adrenoceptors and 5-HT2 receptors
How are TCAs taken
Orally, and highly PPB
How are TCAs metabolised
Hepatic metabolism -> activated, and renal excretion
What is the TCA H1/2
10-20 hrs
What are the unwanted effects?
Atropine like effects, postural hypotension, sedation (H1 antagonism)
Describe the Acute Toxicity of TCA
CNS: Excitement, delirium, seizures, coma, respiratory depression.
CVS: Cardiac dysrhythmias and ventricular fibrillation
What are the drug interactions with TCAs
Other highly PPB drugs such as Aspirin
Hepatic microsomal enzymes eg. oral contraceptives
Potentiate other CNS depressants eg. alcohol
Antihypertensive drugs (monitor BP)
How do MAOIs such as Phenelzine work
non-selective MAOI
What do MAO-A an B correlate to?
A: NA and 5-HT
B: DA
Why do MAOIs have long duration of action
Irreversible inhibitions
What are the rapid effects of penelzine
increased cytoplasmic NA and 5-HT
What are the delayed effects of Phenelzine
Down-regulation of 5-HT and b-adrenoceptors
Describe the pharmacokinetics of pnelezine
Rapid oral absorption, short plasma t1/2, metabolised in liver, excreted in kidneys
What are the unwanted effects of MAO
Atropine like effects, postural hypotension, sedation, weight gain, hepatotoxicity
What are the drug interactions of MAOIs
Cheese reaction- tyramine containing foods + MAOI -> hypertensive crisis
MAO + TCA = hypertensive crisis
MAOI + pethidine -> hyperpyrexia, restlesness, coma and hypotenstion
How do SSRIs like Fluoxetine work?
selective 5-HT reuptake inhibition
less troublesome side effects
Less effective vs severe depression
What are the pharmacokinetics of SSRIs
Oral administration, 18-24hrs working, delayed onset of action (2-4 weeks), competes with TCA for hepatic enzymes therefore toxix
Unwanted effects of SSRI
Nausea, diarrhoea, insomnia, loss of libido
Interact with MAOI
Prozac = Fluoxetine
What are uses of Venlafaxine
Dose dependent reuptake inhibitor
5HT>NA>DA
2nd line treatment of depression
What are the uses of Mirtazapine
a2 receptor antagonist
increases NA and 5HT release
Useful in SSRI intolerant patients
