Antidepressants Flashcards
what is the suspected cause of depression
low levels of serotonin however is still unclear but more likely the reduction in serotonin receptors in the hippocampus
this is why SSRI s take so long to take effect
Mono amine oxadase inhibitors MAOI
- These inhibit the activity of MAO enzymes
- MAO enzymes break down norepinephrine/serotonin and dopamine, so this drug prevents this
NAMES OF DRUG:
- phenelzine
- selegiline (also used in Parkinson’s)
- Tranylcypromine
Side effects:
- weakness
- dizziness
- headache
- fatigue
- weight gain
- impotence
what do MAOI interact with
should NEVER be prescribed in combination with SSRI/Tricyclic as well as analgesics such as morphine/tramadol as they will increase serotonin to potentially dangerous levels causing confusion, hypertension, tremor, coma and even death
MUST BE GIVEN A 14 DAY COOL OFF PERIOD BEFORE STARTING ON ANOTHER ANTI-DEPRESSANT
MAOI and foods high in tyramine
cheese
meats such as venison
alcohol
some green vegetables such as green beans
reversible MAOI
moclobeminde
- reversible inhibition of MAO type A therefore is known as RIMA
- tyramine has less of an effect on frugs like this
- has a short acting period so medications can be changes with only a week wash out period
Tricyclic Antidepressants
act by inhibiting the re-uptake of norepinephrine and serotonin by blocking the transporters responsible fro re-uptake of these neurotransmitters
thus increasing the concentration of neurotransmitters in the synapses and triggering further neurotransmission
what are the uses of tricyclic antidepressants
depression anxiety chronic pain IBS neuralgia OCD nocturnal enuresis PTSD
tricyclic antidepressants cautions
CVD due to the risk of arrhythmias
have antimuscarininc activity that blocks activity of the the muscarinic acetylcholine receptor and so reduce intestinal mobility
They can induce bradycardia followed by tachycardia, reduce bronchial secretions, urinary retention, dry mouth and confusion
tricyclics are very dangerous in overdose so beware of how much you prescribe for a patient and use with caution in patients at high risk of suicide.
tricyclic antidepressants examples
Amitriptyline Clomipramine Imipramine Lofepramine Nortriptyline
Trazodone:
this drug is more sedating
SSRI
Believed to work by increasing levels of neurotransmitter serotonin by limiting its re-absorption and pure SSRI have only a weak affinity for norepinephrine and dopamine transmitters
Serotonin receptors are known as
5-hydroxytryptamine (5-HT)
they are cleaner with generally fewer side effects and tend to be better tolerated by patients
uses of SSRI’s
Depression Anxiety OCD Panic disorder PTSD Eating disorders
where are serotonin receptors found
are found in the peripheral and central nervous systems mediating both excitatory and inhibitory neurotransmission
what do serotonin receptors modulate the release of
GABA Dopamine Epinephrine Norepinephrine Acetylcholine
therefore they influence aggressions anxiety, cognition, learning memory, mood and sleep
SSRI side effects
Sexual: dysfunction and reduced libido
Cardiac: some, especially citalopram, to be used with caution as can cause QT interval prolongation therefore dose dependant with citalopram
Bleeding: affects anticoagulants (i.e. warfarin and aspirin) and also increased risk of GI bleeds
Suicide: possible increased risk of suicide especially in children and adolescents
May only be prescribed in under-18s by a psychiatrist
Overdose: safer than other antidepressants
Epilepsy: may reduce fit threshold
Others include:
Nausea
Rash
Muscle aches
Insomnia
Sweating
the order of the level of toxicity in SSRI Toxicity
citalopram escitalopram Paroxetine Sertraline Fluoxetine
Duloxetine: SNRI (serotonin norepinephrine up-take inhibitor)
uses and side effects
Uses:
Depression
Neuropathic pain (diabetes, fibromyalgia)
Stress urinary incontinence
Side effects:
- nausea
- insomnia
- dizziness
Mirtazapine:
a presynaptic alpha₂-adrenoreceptor antagonist. Also a noradrenergic and specific serotonergic antidepressant NaSSA
uses:
Depression
Anxiety
PTSD
side effects:
Low dose causes drowsiness so best taken at night
Higher dose more stimulant effect
Venlafaxine:
serotonin-norepinephrine re-uptake inhibitor (SNRI)
uses:
Major Depressive Disorder
Anxiety
Panic
Social phobia
Metabolized in the body into desvenlafaxine (by cytochrome P206 isoenzyme in the liver)
Often used in treatment of resistant depression
lithium In bipolar/mania modd stabilisation
possible adverse affects on kidney and thyroid function.
Tricyclics for pain management
work by blocking the re-uptake of Noradrenaline and Serotonin (5-HT) into the nerve endings and increasing their levels in the pain control pathways
Their benefit arises: by their direct effect on pain, and also through beneficial effects on sleep
Prolongation of the QT interval can lead to a life threatening arrhythmia known as
torsades de pointes
CITALOPRAM
People who have more risk factors for QTc prolongation
- Major psychiatric disorders.
- Cardiovascular disease.
- The elderly.
- Women.
