Antidepressants Flashcards
What conditions are antidepressants used to treat?
How long do they take to produce a response?
How long should they be continued after remission?
- Depression, anxiety and eating disorders
- 4-6 weeks in 60-70% of pts
- For a further 6 months before being tapered off
What conditions are TCAs used in?
Depression
- anxiety disorders
- OCD
- chronic pain
- nocturnal enuresis
- narcolepsy
- eating disorders
What conditions are SSRIs used in?
- Depression
- Anxiety disorders
- OCD
- Bulimia nervosa
MAOIs?
- Depression esp atypical; hypersomnia, overeating, anxiety
- Anxiety disorders
- Eating disorders
- Chronic pain
What is the MOA of TCAs e.g amitriptyline?
- Presynaptically block both noradrenaline and serotonin reuptake pumps (and dopamine to a lesser extent).
- Also block muscarinic, alpha-adrenergic and histaminergic receptors leading to many S.Es
What is the MOA of SSRIs e.g fluoxetine, citalopram?
-Selective presynaptic blockade of serotonin reuptake pumps
What is the MOA of SNRIs e.g Venlafaxine?
presynaptic blockade of both the noradrenaline and serotonin reuptake pumps (also dopamine if using high doses). Negligible effects are had on the muscarinic, histaminergic and alpha -adrenergic receptors.
What is the MOA of MAOIs e.g isocarboxazid?
-Non-selective and irreversible inhibition of monoamine oxidase A and B
RIMA (reverse inhibitor of monoamine oxidase A e.g. moclobemide)?
selective and reversible inhibition of monoamine oxidase A
NaSSA (noradrenergic and specific serotonergic antidepressant e.g.
mirtazapine)?
presynaptic alpha 2 receptor blockade (results in increased
noradrenaline and serotonin from presynaptic neurons)
NRIs (noradrenaline reuptake inhibitor e.g. reboxetine)?
selective presynaptic blockade of noradrenaline reuptake pumps.
Side effects of TCAs?
CIs?
- Most S.E are related to their multi-receptor blocking effect
- Sedating
- Cardio toxic; QT interval prolongation, ST segment elevation, heart block, arrhythmias. They are dangerous in OD, esp amitryptyline.
- Muscarinic; Dry mouth, constipation, urinary retention, blurred vision
- Alpha adrenergic; postural hypotension
- Histaminergic; weight gain, sedating
CIs; recent MI, arrhythmias, severe liver disease and mania
S.Es of SSRIs?
CIs?
Fewer antichilinergic S.Es and are less sedating than TCAs
-Class of choice in pts with heart disease or those at risk of OD
- GI disturbance (early on); N+D+V, pain
- Anxiety and agitation (early on)
- Loss of appetite and weight loss (occasionally weight gain)
- Insomnia
- Sweating
- Sexual dysfunction; anorgasmia, delayed ejaculation
CI in mania
MAOIs/RIMA
What is there a serious risk of these drugs interacting with?
What does the reaction result in?
What is the early warning sign?
What is there a risk of when these drugs are administered with other antidepressants with strong serotonergic effects? and how does this affect their use? For the same reason what other class of drugs should also be avoided?
Class is second line due to risk of interactions with food and other drugs.
- Reactions result in the accumulation of amine neurotransmitters and impairs the metabolism of some amines found in drugs and food (cheese reaction). Can lead to a life threatening hypertensive crisis.
- Early warning signs; throbbing headache
- RIMAs are less likely to cause this effect as they reversible inhibit monoamine oxidase A, no dietary restrictions are required.
- Risk of developing potentially fatal serotonin syndrome.
- Class of drugs should not be used for 2-3 weeks after stopping a previous antidepressant or before starring a new one
- Opiates should also be avoided for this reason
What are the S.Es of MAOIs
CIs?
-S.Es are similar to TCAs including postural hypotension and anticholinergic effects
CIs; phaeochromocytoma, cerebrovascular disease, hepaic impairment and mania
