Psychopharmacology Flashcards
List the common drug-classes used to manage depression.
- Selective Serotonin Reuptake Inhibitors (SSRIs) - first-line
- Serotonin and Noradrenaline Reuptake Inhibitors (SNRIs) (v
- Mirtazapine - a noradrenergic and specific serotonin antidepressant (NASSA)
- Tricyclic Antidepressants (TCAs)
- Monoamine Oxidase Inhibitors (MOIs)
Describe the MoA of SSRIs
SSRIs inhibit the re-uptake of serotonin from the synaptic cleft, resulting in more serotonin in the synaptic cleft and this more serotonergic synaptic transmission. SSRIs have also been shown to decrease neuroinflammation through decreased levels of IL-6; neuroinflammation has been implicated in depression.
Why are SSRIs the first-line treatment for depression?
Selective serotonin reuptake inhibitors (SSRIs) are considered first-line treatment for the majority of patients with depression. This is because they are as effective as other antidepressants but because they are more ‘selective’ to only serotonin reuptake proteins, they have fewer side-effects. They also have a high toxic dose making it harder to overdose.
When are the different SSRIs used?
Pls suggest edits to this card
- Citalopram (although see below re: QT interval) and fluoxetine are currently the preferred SSRIs (unsure this is really true tbh!!!)
- Sertraline is useful post myocardial infarction as there is more evidence for its safe use in this situation than other antidepressants
What are the main side-effects and interactions of SSRIs?
- The main side-effects of SSRIs are gastrointestinal including nausea, vomiting, appetite and weight change. There is increased risk of GI bleeding with SSRIs, so if they are prescribed with NSAIDs they should be taken with a PPI.
- Hyponatraemia
- Patients should also be counselled to be vigilant for increased anxiety and agitation after starting an SSRI.
- Citalopram can cause QT prolongation in a dose-dependent manner, and so should be avoided with those with pre-exiting conditions.
- Avoid SSRIs if the patient is being prescribed triptans or warfarin or heparin.
- Do not prescribe with monoamine oxidase inhibitors due to risk of serotonin syndrome.
Give an example of a SNRI
Serotonin and Noradrenaline Reuptake Inhibitors (SNRIs)
These include venlafaxine and duloxetine
What are the side-effects of SNRIs?
Because these drugs also increase the amount of noradrenaline in the synapse, side effects include constipation and hypertension as well as all the SSRI symptoms (gastrointestinal symptoms, anxiety, agigation).
What antidepressant is prefered for use in the elderly, and why?
Mirtazapine has fewer side effects and interactions than many other antidepressants and so is useful in older people who may be affected more or be taking other medications. Two side effects of mirtazapine, sedation and an increased appetite, can be beneficial in older people that are suffering from insomnia and poor appetite.
What is the MoA of tricyclic antidepressants (TCAs) and list a few
TCAs work by inhibiting the reuptake of serotonin and noradrenaline (like SNRIs). I think they are technically SNRIs but are their own drug class because of their tricyclic structure?. TCAs include:
- Amitriptyline
- Clomipramine
- Imipramine
Why are TCAs not used as much for the management of depression?
Tricyclic antidepressants (TCAs) are used less commonly now for depression due to their side-effects and toxicity in overdose - lethal cardiotoxicity. They are however used widely in the treatment of neuropathic pain, where smaller doses are typically required.
List the common side-effects of TCAs
Common side-effects are due to anticholinergic effect
- Drowsiness
- Dry mouth
- Blurred vision
- Constipation
- Urinary retention which can lead to overflow incontinence
- Lengthening of QT interval
Why are monoamine oxidase inhibitors rarely used?
MOIs inhibit the metabolism of monoamines, thus increasing their synaptic levels. They are rarely used due to the danger of hypertensive crises (‘cheese reaction’) which occurs due to build-up of NA after eating tyramine-rich foods such as mature cheese, yeast extracts and fermented soya beans. They should also not be combined with other antidepressants.
How long after initiation of an antidepressant should a patient be reviewed?
- Following initiation of antidepressant therapy, patients should normally be reviewed by a doctor after 2 weeks.
- For patients under the age of 30 years or at increased risk of suicide, they should be reviewed after 1 week.
What are the indications and therapeutic range for lithium?
Lithium is mood stabilising drug used most commonly prophylactically in bipolar disorder but also as an adjunct in refractory depression. It has a very narrow therapeutic range (0.6-1.0 mmol/L) and a long plasma half-life being excreted primarily by the kidneys.
What are the side-effects of lithium?
Adverse effects
- Nausea/vomiting, diarrhoea
- Fine tremor
- Nephrotoxicity: polyuria and polydipsia secondary to nephrogenic diabetes insipidus
- Thyroid enlargement, may lead to hypothyroidism
- ECG: T wave flattening/inversion
- Weight gain
- Idiopathic intracranial hypertension
At what levels is lithium toxic?
Lithium is toxic above 1.2 mmol/L
How is the patient on lithium monitored?
Lithium is toxic above 1.2 mmol/L, therefore patient should be monitored weekly after just started and after each dose changeuntil concentrations are stable.
- Once established, lithium blood level should ‘normally’ be checked every 3 months. Levels should be taken 12 hours post-dose.
- Thyroid and renal function should be checked every 6 months.
- Patients should be issued with an information booklet, alert cardand record book