Psychopharmacology Flashcards
What are some generalised Pharmacology strategies?
Indication - establish diagnosis and identify symptoms that will be used to monitor therapy response.
Choice of Agent and dosage - select an agent with acceptable side effect profile and use lowest effective dose.
Management - Adjust dose for optimum benefit, safety and compliance. Strive for the simplest regime.
What are some indications for the use of antidepressants?
Unipolar and bipolar depression
Organic mood disorders
Schizoaffective disorder Anxiety disorders including OCD, panic, social phobia and PTSD.
What are the general guidelines for antidepressant use?
Antidepressant selection is based on past Hx of a response, side effect profile and coexisting medical conditions.
Delay of 3-6weeks before symptoms improve
If no improvement after at least 2 months then switch to another antidepressant or augment with another agent.
What are some different types of Antidepressants?
Tricyclic antidepressants Monoamine Oxidase Inhibitors Selective serotonin Reuptake Inhibitors. Serotonin/Noradrenaline reuptake inhibitors (SNRIs). Novel antidepressants.
What are some disadvantages of Tricyclic antidepressants?
Have may side effects including antihistaminic, anticholinergic and antiadrenergic.
Lethal in overdose even if it is a week long supply.
Can cause QT lengthening.
What are some examples of Tertiary TCAs?
Imipramine
Amitriptyline
Doxepin
Clomipramine
What are some characteristics of tertiary TCAs?
Act predominantly on serotonin receptors.
Have active metabolites including desipramine and nortiptyline.
Side chains are prone to cross react with other types of receptors which leads to more side effects.
What are some characteristics of secondary TCAs?
Often metabolites of tertiary amines.
Primarily block noradrenaline.
Side effects are same as tertiary but generally less severe.
Examples include Desipramine, Nortriptyline
What are some characteristics of Monoamine Oxidase Inhibitors?
Bind irreversibly to monoamine oxidase thereby preventing inactivation of amines such as dopamine, norepinephrine and serotonin leading to increased synaptic levels.
Very effective for depression
What are some disadvantages of Monoamine Oxidase Inhibitors?
Side effects include orthostatic hypotension, weight gain, dry mouth, sedation, sexual dysfunction and sleep disturbance.
Hypertensive crisis can develop if they are taken with tyramine rich foods or sympathomimetics e.g. cheese.
Serotonin syndrome can develop if taken with meds that increase serotonin or have sympathomimetic actions. To avoid wait 2 weeks before switching from SSRI to MAOI. Fluoxetine need to wait 5 weeks as long half-life.
What are the symptoms of Serotonin syndrome?
Abdominal pain Diarrhoea Sweats Tachycardia HTN Myoclonus Irritability Delirium Hyperpyrexia Cardiovascular shock Death
What are some characteristics of Selective Serotonin Reuptake Inhibitors?
Block pre-synaptic serotonin reuptake.
Treat both anxiety and depressive symptoms.
Very little risk of cardio toxicity in overdose.
What are some disadvantages of SSRIs?
Side effects - GI upset, sexual dysfunction, anxiety, restlessness, nervousness, insomnia, fatigue or sedation, dizziness.
Can develop a discontinuation syndrome with agitation, nausea, disequilibrium and dysphoria.
What are the advantages of Paroxetine?
Short half-life with no active metabolite
Sedating properties offers good initial relief from anxiety and insomnia.
What are the disadvantages of Paroxetine?
Significant CYP2D6 inihibtion.
Sedating, weight gains and more anticholingeric effects.
Likely to cause discontinuation syndrome.
What are the disadvantages of Sertraline?
Max absorption requires a full stomach.
Increased number of GI adverse drug reactions.
What are the advantages of Sertraline?
Very weak P450 interactions
Short half-life with lower build up of metabolites.
Less sedating than paroxetine.
What are the advantages of Fluoxetine (Prozac)?
Long half-life so decreased incidence of discontinuation syndromes.
Good for patients with noncompliance issues.
Initially activating so may provide increased energy.
Can give 1 20mg tablet to taper someone off SSRI.
What are the disadvantages of Fluoxetine?
Long half-life and active metabolite build up. Not a good choice in patient with hepatic illness.
Significant P450 interactions so not good for patients on a number of meds.
Initial activation may increase anxiety and insomnia.
More likely to induce mania than some other SSRIs.
What are the advantages of Citalopram?
Low inhibition of p450 enzymes so fewer drug-drug interactions.
Intermediate half-life
What are the disadvantages of Citalopram?
Dose dependent QT interval prolongation with doses of 10-30mg daily due to this risk doses of >40mg are not recommended.
Can be sedating (has mild antagonism at H1 histamine receptors)
GI side effects (but less than sertraline).
What are the advantages of Escitalopram?
Low overall inhibition of P450s enzymes so fewer drug-drug interactions.
Intermediate half-life
More effective than citalopram in acute response and remission.
What are the disadvantages of Escitalopram?
Dose-dependent Qt interval prolongation with doses <40mg daily
Nausea
Headache
What are the advantages of Fluvoxamine?
Shortest half-life
Found to possess soma analgesic properties
What are the disadvantages of Fluvoxamine?
Shortest half-life GI distress Headaches Sedation Weakness Strong inhibitor of CYP1A2 and CYP2C19
What is the action of serotonin/Norepinephrine reuptake inhibitors (SNRIs)?
Inhibit both serotonin and noradrenergic reupatke like TCA but without the antihistamine, anticholinergic and antiadrenergic side effects.
Used for depression, anxiety and possibly neuropathic pain.
What are the advantages of Venlafaxine?
Minimal drug interactions and almost no P450 activity.
Short half-life and renal clearance avoids build-up.
What are the disadvantages of Venlafaxine?
Can cause a 10-15mmHg dose dependent increase in diastolic BP.
May cause nausea, primarily with immediate release tabs.
Discontinuation syndrome
Noted to cause QT prolongation
Sexual side effects
What are the advantages of duloxetine?
Efficacy for physic symptoms of depression
Less BP increase compared to venlafaxine.
What are the disadvantages of Duloxetine?
CYP2D6 and CYP1A2 inhibitors
Cannot break capsule as active ingredient not stable within stomach.
Higher drop out rate.
What are the advantages of the novel antidepressant Mirtazapine?
Different mechanism of action may provide good augmentation strategy to SSRIs. 5HT2 and 5HT3 receptor antagonist
Can be utilised as a hypnotic at lower doses secondary to antihistaminic effects.
What are the disadvantages of Mirtazapine?
Increases serum cholesterol by 20% in 15% of patients and increases triglycerides in 6%.
Very sedating at lower doses
Associated with weight gain, particularly with doses<45mg.
What are the advantages of Buproprion?
Good augmenting agent
mechanism of action is likely reuptake inhibition of dopamine and norepinephrine.
No weight gain, sexual side effects, sedation or cardiac interactions.
Low induction of mania
2nd line ADHD agent so consider if co-occuring diagnosis.