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Flashcards in SSRI Deck (8)
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What is the mechanism of action od SSRIs?

Selective serotonin reuptake inhibitors (SSRIs) preferentially inhibit neuronal reuptake of 5-HT from the synaptic cleft, thereby increasing its availability for neurotransmission


Why are SSRIs preferred over tricyclic antidepressants?

The efficacy of the two drug classes in the treatment of depression is similar. However, SSRIs are generally preferred as they have fewer adverse effects and are less dangerous in overdose.


What are the important adverse effects of SSRIs?

Common adverse effects include GI upset, changes in appetite and weight (loss or gain), and hypersensitivity reactions, including skin rash. Hyponatraemia is an important adverse effect, particularly in the elderly, and may present with confusion and reduced consciousness. Suicidal thoughts and behaviour may be increased in patients on SSRIs. They may lower the seizure threshold (the evidence for this is conflicting). Some (e.g. citalopram) can prolong the QT interval, predisposing to arrhythmias. SSRIs also increase the risk of bleeding. At high doses, in overdose, or in combination with other serotonergic drugs (e.g. other antidepressants, tramadol), SSRIs can cause serotonin syndrome. 


What happens when SSRIs are withdrawn suddenly?

Sudden withdrawal of SSRIs can cause GI upset, neurological and influenza-like symptoms and sleep disturbance.


What drugs are important to avoid when the patients are on SSRI?

SSRIs should not be given with ✗monoamine oxidase inhibitors and other ▴serotonergic drugs (e.g. tramadol), as together they may precipitate serotonin syndrome. Gastroprotection should be considered for patients taking SSRIs with aspirin or NSAIDs, due to an increased risk of bleeding. Bleeding risk is also increased where SSRIs are co-prescribed with anticoagulants. They should not be combined with other ▴drugs that prolong the QT interval, such as antipsychotics.


What is the typical regimen for SSRI?

SSRIs are prescribed for oral administration. They should be started at a low dose to be taken regularly, usually once a day. A typical starting prescription might be for citalopram 20 mg daily. The dose is increased as necessary according to response. Lower starting and maximum doses are prescribed for elderly patients.


How can you improve the bioavailability of SSRI?

Citalopram is available as tablets and as oral drops, which can be mixed with water or other drinks. As the oral drops have greater bioavailability than tablets, they are prescribed at different doses. For example, one 20 mg citalopram tablet is equivalent to 16 mg citalopram in four oral drops.