Psychopharmacology in Psychiatry Flashcards
(81 cards)
What is Indication?
Indication: Establish a diagnosis and identify
the target symptoms that will be used to
monitor therapy response.
Why is “choice of agent and dosage” important?
Choice of agent and dosage: Select an
agent with an acceptable side effect profile
and use the lowest effective dose.
Remember the delayed response for many
psych meds and drug-drug interactions.
What is management of medications?
Management: Adjust dosage for optimum
benefit, safety and compliance. Use
adjunctive and combination therapies if
needed however, always strive for the
simplest regime.
*If initial treatment isn’t successful. Keep as simple as possible
What is 2 general guidelines when prescribing Antidepressants?
Antidepressant efficacy is similar!! (Similar side effects) - All work at about a 70% response rate
Selection is based on past history of a response, side effect profile and coexisting medical conditions.
How long do anti-depressants take to work and how long should we wait before swapping them?
There is a delay typically of 2-4 weeks after a
therapeutic dose is achieved before symptoms improve. (Delayed response to do with amygdala receptor changes).
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 conditions would we prescribe Anti-depressants for?
- 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. (Evidence is mixed for this)
What are the different classifications of Antidepressants?
- Selective Serotonin Reuptake Inhibitors (SSRIs)
- Tricyclics (TCAs)
- Monoamine Oxidase Inhibitors (MAOIs)
- Serotonin/Noradrenaline Reuptake Inhibitors (SNRls)
- Novel antidepressants (work slightly differently)
How do SSRI’s work?
By blocking the presynaptic serotonin reuptake
What are SSRI’s used to treat?
Anxiety and depressive symptoms
What are the most common side effects of SSRI’s ?
Most common side effects include Gl upset,
sexual dysfunction (30%+!), anxiety,
restlessness, nervousness, insomnia, fatigue or sedation, dizziness
Very little risk of cardiotoxicity in overdose
Can develop a discontinuation syndrome with
agitation, nausea, disequilibrium and dysphoria
What is activation syndrome seen in SSRI use?
Cause increased serotonin. It can be distressing for the patient.
Nausea, increased anxiety, panic and
agitation.
Typically last 2 — 10 days (Warn patients!)
*If had activation syndrome in past could give short course benzos when starting
What is Discontinuation syndrome?
Agitation, nausea, disequilibrium and dysphoria
More common with shorter half life drugs
so conisder switching to fluoxetine.
Takes about 3 weeks to get out of system
What are the Pros and Cons of Fluoxetine (Prozac)?
Fluoxetine (Prozac) Pros;
- Long half-life so decreased incidence of discontinuation
syndromes. Good for pts with medication noncompliance issues
- Initially activating so may provide increased energy
- Secondary to long half-life, can give one 20m tab to taper someone off SSRI when trying to prevent SSRI Discontinuation Syndrome
Fluoxetine (Prozac) 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 patients already on a number of meds
- Initial activation may increase anxiety and insomnia
- More likely to induce mania than some of the other SSRls
What are the Pros and Cons of Sertraline?
Sertraline Pros;
- Very weak P450 interactions (only slight CYP2D6)
- Short half-life with lower build-up of metabolites
- Less sedating when compared to paroxetine
Sertraline Cons;
- Max absorption requires a full stomach
- Increased number of Gl adverse drug reactions
What are the Pros and Concs of Tricyclic Antidepressants (TCA’s) in general?
Very effective but potentially unacceptable
side effect profile i.e. antihistaminic, 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 Tertiary TCA’s and how do they work?
- Have tertiary amine side chains
- Side chains are prone to cross-react with other types of receptors, which leads to more side effects
- Examples: lmipramine, amitriptyline, doxepin, clomipramine
- Have active metabolites including desipramine and nortriptyline
(A metabolite is any substance produced during metabolism (digestion or other bodily chemical processes)).
What are Secondary TCA’s and how do they work?
- Are often metabolites of tertiary amines
- Primarily block noradrenaline
- Side effects are the same as tertiary TCAs but generally are less severe
- Examples: Desipramine, notrtriptyline
(A metabolite is any substance produced during metabolism (digestion or other bodily chemical processes)).
What are Monoamine Oxidase Inhibitors (MAOI’s) and how do they work?
- 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!! (Prevent breakdown of tyramine - increase BP, increase side effects. Foods like Cheese, red wine, some beans, some processed meats) - Not used very often
How can Serotonin Syndrome occur in MAOI’s and what should you do as a caution?
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 SNRI’s work?
Serotonin/Norepinephrine reuptake inhibitors (SNRls);
- 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 (at low doses 10% of dose)
Examples;
- Venlafaxine
- Duloxetine
- Vortioxetine
What drug is most commonly used for Neuropathic pain?
Amitriptyline (A SNRI) at low doses 10% of normal dose
What are the Pros and Cons for Venlafaxine?
Venlafaxine Pros;
- Minimal drug interactions and almost no P450 activity
- Short half life and fast renal clearance avoids build-up (good for geriatric populations)
Venlafaxine Cons;
- Can cause a 10-15 mmHG dose dependent increase in diastolic
- May cause significant nausea, primarily with immediate-release (IR) tabs
- Can cause a bad discontinuation syndrome, and taper recommended after 2 weeks of administration
- Sexual side effects in >30%
What are the Pros and Cons for Duloxetine?
Duloxetine Pros;
- Some data to suggest efficacy for the physical symptoms of depression
- Thus far less BP increase as compared to
venlafaxine, however this may change in time
Duloxetine Cons;
- CYP2D6 and CYPIA2 inhibitor
- Cannot break capsule, as active ingredient not stable within the stomach
- In pooled analysis had higher drop out rate
What are the Pros and Cons of Vortioxetine?
Vortioxetine SNRI Pros;
- Less Gl side effects
- Less change in blood pressure
Cons;
- Expensive (GP’s cannot prescribe, SNRI expensive, less side effects - specialist only)
