Anti-depressant Flashcards
What are the two classes of phsychoses? symptoms of depresion
Schizophrenia affective disorder (moods)-mania or depression
misery/low self selfeem, motivation, loss of apathy, pessimism, loss of enjoyment of actvity
Slowness of thought and action, loss of libido, loss of apetite and sleep distrubances
What are the 2 main types of depression?
Unipolar-depressive disorder-mood swings are always in same direction
late adult onset
either reacting (from stress, non familial)
Endogenous reaction (unrelated to stress, familial pattern)
drug treatment similar to bipolar
Bipolar depression/manic depression
oscilatting depression/mani
Less common, early adult onset-strong hereditary tendency
same drugs and lithium (mood stabiliser-reduce IP3/cAMP)
What is the monoamine theory of depression?
Biochemical idea for origin of depression
depression comes from deficit of central monoamine transmission (mania being functional excess)
NA and 5HT changes–with evidence
Biochem evidence inconsistant (as drugs dont all work (like methydopa redce mood, but MAO inhbitors increase mood), cocaine has no effect
all anti depressants-slow-delayed activity-why work so slow if acting on the monoamine (adaptive changes in time?=> down regulation of a2, B adreno receptors and 5HT receptors-
reduction in monoamine in urine-less turnover in brain
general conclusion-HPA (Hipo, Pit, adrenal) axis role
Hipocampal neurodegeneration?
alldrugs used are consistant with MA theory
What are the 1st group of antidepressant? mechanism of action
TCAs-eg: amitriptyline (tricyclic antidepressors)
act as -mono amine reuptake inhbitors-reduce NA and 5HT reuptake-longer in synapse
do both about as well
also act on lot of other-reduce a2 adreno (also on 5HT neurons)-increase release)
MACh, histamine-also interact
delayed down regulation of B-adreno/5HT R-maybe more what causes the downregulation
Describe pharmokokinetic of TCA and side effects?
Rapid oral absorb-and protien bound (95%)–hepatic metabolism-glucoronide conjugated-some active metabolites
last about 10-20h
at therapeutic dosages–atropine effect (dry mouth/skin, etc)-inhbiting mAChR
Postural hypotension
Sedation-via Histamine receptors-can be good for sleep deprivation
acute toxicity–CNS (excitement, delirium, seizures->coma, resp depression)
CVS-cardiac dysrhytmias-mAChR inhbitor and NA increase
often used for Attempted suicide
What drugs do TCA interact with?
because highly protein bound-interact with many other-displace and increase dose–like aspirin, phenotoin (also protein bound), warfarin (also-will displace and make it toxic)
on hepatic enzymes-drugs that compete for degradation (increase conc)-neuroleptic, antiphyschotics, oral contraceptives, FLUOXETINE (SSRI)
Potentiate CNS depressants (like alcohol)-double whammy with depression
Antihypertensive drugs-have to monitor
What is the 2nd group of antidepressant drug? mechanism of action
Monoaminde oxidase inhbitors-phenelzine
2 main types of MAOi–MAO-A-destroy NA and 5HT
MAOB-Dopamine
MAOI inhbit both-non selective (try recently to make them selective to A)
Irreversible inhbiton-long action
RAPID effect-decrease breakdown in cell-increase cytoplasmic NA and 5HT-enhanced release after, increase synaptic conc
delayed effects as well-downregulation of B2 receptor and 5HT receptors
(maybe inhition of other enzymes)
moclobemide-reversible MAO-A inhbitor-less drug interaction
Describe pharmokokinetic of MAOi and side effects?
Oral-fast absorb, short plasma t1/2 but irreversible so act long time
Metabolised in liver-excreted in urine
atropine like effect (less than TCA), postural hypotension
Sedation-seizure in overdose
weight gain-appetite increase-can be excessive
Hepatotoxicity for hydrazine class
What drugs do MAOi interact with?
Cheese reaction–tyramine containing foods + MAOi (tryamine is symathetic mimetic effects)–hypertensive effects because MAOi stop breakdown of tyramine–reduce yeast containing products
MAOi +TCA-hypertensive episodes
MAOi + pethidine (opiod analgesic) -> hyperpyrexia, restlessness, coma
moclobemide-reversible MAO-A inhbitor-less drug interaction (more tyramine breakdown), less duration of action2-3 times a day
What is the 3rd group of antidepressant drug?
Selective serotonine Reuptake inhbitor-fluoxetine (SSRI)
Selective 5HT inhbiton of reuptake
Less troublesome side effects and safer in overdose (no cheese reaction)
But less effective for severe depression
most common prescribed Antidepressant (fluoxetine-prozac (market name)
Describe pharmokokinetic of SSRI and side effects?
Pharma-p.o administration
long plasma t1/2
slow onset of action
Fluoxetine compete with TCA for hepatic enzymes-avoid co
Fewer side effects than other-nausea, vomittingm insomnia and loss of libido
Interact with MAOi (enhance too much)
but still
