selective serotonin reuptake inhibitors

Selective serotonin reuptake inhibitors (SSRIs) are considered first-line treatment for the majority of patients with depression.
citalopram (although see below re: QT interval) and fluoxetine are currently the preferred SSRIs
sertraline is useful post myocardial infarction as there is more evidence for its safe use in this situation than other antidepressants
SSRIs should be used with caution in children and adolescents. Fluoxetine is the drug of choice when an antidepressant is indicated

Adverse effects
gastrointestinal symptoms are the most common side-effect
there is an increased risk of gastrointestinal bleeding in patients taking SSRIs. A proton pump inhibitor should be prescribed if a patient is also taking a NSAID
patients should be counselled to be vigilant for increased anxiety and agitation after starting a SSRI
fluoxetine and paroxetine have a higher propensity for drug interactions

Citalopram and the QT interval
the Medicines and Healthcare products Regulatory Agency (MHRA) released a warning on the use of citalopram in 2011
it advised that citalopram and escitalopram are associated with dose-dependent QT interval prolongation and should not be used in those with: congenital long QT syndrome; known pre-existing QT interval prolongation; or in combination with other medicines that prolong the QT interval
the maximum daily dose is now 40 mg for adults; 20 mg for patients older than 65 years; and 20 mg for those with hepatic impairment

Interactions
NSAIDs: NICE guidelines advise 'do not normally offer SSRIs', but if given co-prescribe a proton pump inhibitor
warfarin / heparin: NICE guidelines recommend avoiding SSRIs and considering mirtazapine
aspirin: see above
triptans: avoid SSRIs

Following the 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. If a patient makes a good response to antidepressant therapy they should continue on treatment for at least 6 months after remission as this reduces the risk of relapse.

When stopping a SSRI the dose should be gradually reduced over a 4 week period (this is not necessary with fluoxetine). Paroxetine has a higher incidence of discontinuation symptoms.

Discontinuation symptoms
increased mood change
restlessness
difficulty sleeping
unsteadiness
sweating
gastrointestinal symptoms: pain, cramping, diarrhoea, vomiting
paraesthesia

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