Psychopharmacology - antidepressants Flashcards
1
Q
Disorders indicated for antidepressants
A
- Unipolar and bipolar depression
- Organic mood disorders
- Scizoaffective disorder
- Anxiety disorders: OCD, GAD, panic, social, PTSD
- Premenstrual dysphoric disorder
- Personality disorder
2
Q
How do antidepressants work
A
- WE DON’T FUCKING KNOW
- Involve neurotransmitters → serotonin, dopamine, noradrenaline etc
- Increase level of neurotransmitters in brain
- Alters receptos in the brain
- 60-70% response rate
3
Q
General guidelines for antidepressant use
A
- All have similar efficacy → selected based on past history of response, side effect profile and co-existing conditions
- 2-4 week delay in response after therapeutic dose is reached
- Trial for at least 2 months before switching to another antidepressant or augmenting with another agent
4
Q
Classifications of antidepressants
A
- Tricyclics (TCA’s)
- Monoaminase inhibitors
- Selective serotonin reuptake inhibitors (SSRI’s)
- Serotonin/ noradrenaline reuptake inhibitors (SNRI’s)
- Novel antidepressants
5
Q
TCAs
A
- Effective but large side-effect profile → antihistaminergic and anticholinergic
- Increases dopamine, serotonin and noradrenaline ]
- Life-threatening in overdose
- Causes QT interval lengthening → arrhythmia
*
6
Q
Tertiary TCA’s
A
- Tertiary amine side chain → prone to cross-react with other receptions and side effects
- Imipramine, amitriptyline, doxepin, clomipramine
- Active metabolites → desipramine, nortriptyline
7
Q
Secondary TCA’s
A
- Metabolites of tertiary amines
- Primary target on noradrenaline
- Similar side effect profile to tertiary TCA’s, less severe
- Desipramine, nortriptyline
8
Q
Monoamine oxidase inhibitors (MAOIs)
A
- Irreversible binding to monoamine oxidase receptor → prevents inactivation of amines
- Increases synaptic noradrenaline, dopamine and serotonin
- Rarely prescribed, effective for resistant depression
- Large side-effect profile → orthostatic hypotension, weight gain, dry mouth, sedation, sexual dysfunction and sleep disturbances
- Must avoid cheese → tyramine-rich foods cause hypertensive crisis
- High risk of serotonin syndrome in combination with other psychotropic medications
9
Q
Selective serotonin reuptake inhibitors (SSRI’s)
A
- Block presynaptic serotonin reuptake
- Treats both anxiety and depression
- Side effects → GI upset, sexual dysfunction, anxiety, restlessness, nervousness, insomnia, fatigue, sedation, dizziness
- Low risk of cardiotoxicity in overdose
- Discontinuation syndrome → agitation, nausea, dysphoria, disequilibrium
10
Q
Activation syndrome
A
- Temporary symptoms caused by increase in serotonin
- Nausea, increased annuity, panic and agitation
- 2-10 days
- Must warn patients
11
Q
Discontinuation syndrome
A
- More common in shorter half-life drugs
- Consider switch to fluoxetine
- Agitation, nausea, disequilibrium and dysphoria
12
Q
Sertraline
A
- Pros
- Short half-life and lower build up of metabolites
- Less sedation than paroxetine
- Cons
- Max absorption requires full stomach
- Increased number of GI adverse drug reactions
13
Q
Fluoxetine
A
- Pros
- Long half-life → lower incidence of discontinuation syndrome
- Initially activating → increases energy
- Can be used for discontinuation of another SSRI
- Cons
- Long half-life and active metabolites
- High interaction with P450 enzyme
- Initial actiation → anxiety and insomnia
- More likely to induce mania than other SSRI’s
14
Q
SNRI
A
- Inhibits both serotonin and noradrenaline without side effect profile of TCA’s - antihistamine, antiadrenergic or anticholinergic side effects
- Indications → depression, anxiety and neuropathic pain
- Venlafaxine, duloxetine
15
Q
Venlafaxine (my current poison)
A
- Pros
- Low drug reactions → no p450 activity
- Short half-life → fast renal clearance (good for geriatric pop)
- Cons
- Dose dependant increase in diastolic BP
- Risk of nausea in immediate release formulation
- Discontinuation syndrome → fucking dire
- QT prolongation
- Sexual dysfunction → >30%
