Psychopharmacology Flashcards
Antidepressant efficacy is similar so what is selection based on?
Past history of a response, side effect profile and coexisting medical conditions.
There is a delay typically of 2-4 weeks after a therapeutic dose is achieved before symptoms improve.
If no improvement is seen after a trial of adequate length (at least 2 months) and adequate dose, either switch to another antidepressant or augment with another agent.
What are indications for antidepressant use?
Unipolar and bipolar depression, organic mood disorders, schizoaffective disorder, anxiety disorders including OCD, panic, social phobia, PTSD
(premenstrual dysphoric disorder and impulsivity associated with personality disorders)
What are the classifications of antidepressants?
Tricyclics (TCAs)
Monoamine Oxidase Inhibitors (MAOIs)
Selective Serotonin Reuptake Inhibitors (SSRIs)
Serotonin/Noradrenaline Reuptake Inhibitors (SNRIs)
How do SSRIs work and what are the side effects?
Block the presynaptic serotonin reuptake
Treat both anxiety and depressive sx
Most common side effects include GI upset, sexual dysfunction (30%+!), anxiety, restlessness, nervousness, insomnia, fatigue or sedation, dizziness
Very little risk of cardiotoxicity in overdose
Can you develop a discontinuation syndrome with SSRIs?
Yes, Can develop a discontinuation syndrome with agitation, nausea, disequilibrium and dysphoria
More common with shorter half life drugs so conisder switching to fluoxetine.
What is activation syndrome with SSRIs?
Activation Syndrome: Cause increased serotonin. Can be distressing for patient.
Nausea, increased anxiety, panic and agitation.
Typically last 2 – 10 days
Fluoxetine (Prozac): what are some pros and cons of this medication?
Pros
- Long half-life so decreased incidence of discontinuation syndromes. Good for pts with medication noncompliance issues
- Secondary to long half life, can give one 20mg tab to taper someone off SSRI when trying to prevent SSRI Discontinuation Syndrome
Cons
- Long half life and active metabolite may build up (e.g. not a good choice in patients with hepatic illness)
- Significant P450 interactions so this may not be a good choice in pts already on a number of meds
SERTRALINE: What are the pros and cons of this SSRI?
Pros
- Very weak P450 interactions (only slight CYP2D6)
- Short half life with lower build-up of metabolites
- Less sedating when compared to paroxetine
Cons
- Max absorption requires a full stomach
- Increased number of GI adverse drug reactions
What are the disadvantages of TCAs side effect profile?
Very effective but potentially unacceptable side effect profile i.e. antihistaminic (sedative effects), anticholinergic, antiadrenergic
Lethal in overdose (even a one week supply can be lethal!)
Can cause QT lengthening even at a therapeutic serum level
What are MAOIs very effective and what are their side effects?
Bind irreversibly to monoamine oxidase thereby preventing inactivation of amines such as norepinephrine, dopamine and serotonin leading to increased synaptic levels
Are very effective for resistant depression
Side effects include orthostatic hypotension, weight gain, dry mouth, sedation, sexual dysfunction and sleep disturbance
Hypertensive crisis can develop when MAOI’s are taken with tyramine-rich foods or sympathomimetics. *Cheese Reaction!!
What is Serotonin syndrome and how can it be avoided?
Serotonin Syndrome can develop if take MAOI with meds that increase serotonin or have sympathomimetic actions.
Serotonin syndrome sx include abdominal pain, diarrhea, sweats, tachycardia, HTN, myoclonus, irritability, delirium. Can lead to hyperpyrexia, cardiovascular shock and death.
To avoid need to wait 2 weeks before switching from an SSRI to an MAOI. The exception of fluoxetine where need to wait 5 weeks because of long half-life.
How do SNRIs work and what are they used for?
Inhibit both serotonin and noradrenergic reuptake like the TCAS but without the antihistamine, antiadrenergic or anticholinergic side effects
Used for depression, anxiety and possibly neuropathic pain
E.g. Duloxetine, Venlafaxine, Vortioxetine
What is an example of a novel antidepressant?
Mirtazapine
Different mechanism of action may provide a good augmentation strategy to SSRIs. Is a 5HT2 and 5HT3 receptor antagonist
Can be utilised as a hypnotic at lower doses secondary to antihistaminic effects
Very sedating at lower doses
What are examples of SSRIs?
Citalopram, Fluoxetine or Sertraline
What is the first line med for deppression?
SSRI
Less desirable choices include Paroxetine and Mirtazapine because of sedation and wt gain.
Not a dual reuptake inhibitors if treatment niave.
Not a TCA because of side effects
How is treatment resistance managed?
Combination of antidepressants eg SSRI or SNRI with Mirtazepine
Adjunctive treatment with Lithium
Adjunctive treatment with atypical antipsychotic eg Quetipaine, Olanzapine or Aripiprazole
ECT!!
When should prophylaxis be used in the context of antidepressants?
First episode continue for 6mth to a year
Second episode continue for 2 years
Third episode discuss life long
When are mood stabilisers indicated?
Bipolar, cyclothymia, schizoaffective
Classes: Lithium, anticonvulsants, antipsychotics
What factors predict positive response to lithium?
Prior long-term response or family member with good response
Classic pure mania
Mania is followed by depression
What is done before starting lithium and how is it monitored?
Before starting :Get baseline U&E and TSH. In women check a pregnancy test- during the first trimester is associated with Ebstein’s anomaly
Monitoring: Steady state achieved after 5 days- check 12 hours after last dose. Once stable check level 3 months and TSH and creatinine 6 months.
Goal: blood level between 0.6-1.2
