Selective serotonin reuptake inhibitors

Question 1

Indications

Answer 1

1. As first-line treatment for moderate-to-severe depression, and in mild depression if psychological treatments fail.
2. Panic disorder.
3. Obsessive compulsive disorder.

Question 2

Mechanisms of action

Answer 2

Selective serotonin reuptake inhibitors (SSRIs) preferentially inhibit neuronal reuptake of serotonin (5-HT) from the synaptic cleft, thereby increasing its availability for neurotransmission. This appears to be the mechanism by which SSRIs improve mood and physical symptoms in depression and relieve symptoms of panic and obsessive disorders.

Question 3

Adverse effects

Answer 3

Common adverse effects include gastrointestinal upset, appetite and weight disturbance (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. SSRIs lower the seizure threshold and some (e.g. citalopram) prolong the QT interval and can predispose to arrhythmias.

Question 4

Warnings

Answer 4

SSRIs should be prescribed with caution where there is a particular risk of adverse effects, including in epilepsy and peptic ulcer disease. In young people, SSRIs have poor efficacy and are associated with an increased risk of self-harm and suicidal thoughts, so should only be prescribed by specialists. As SSRIs are metabolised by the liver, dose reduction may be required in people with hepatic impairment.

Question 5

Interactions

Answer 5

SSRIs should not be given with monoamine oxidase inhibitors as they both increase synaptic serotonin levels and together may precipitate serotonin syndrome.

Question 6

Prescribing

Answer 6

PO

Question 7

Administration

Answer 7

Tablets and drops

Question 8

Communication

Answer 8

Advise patients that treatment should improve symptoms over a few weeks, particularly sleep and appetite. Discuss referring them for psychological therapy, which may offer more long-term benefits than drug treatment. Explain that they should carry on with drug treatment for at least 6 months after they feel better to stop the depression from coming back (2 years for recurrent depression). Warn them not to stop treatment suddenly as this may cause a tummy upset, flu-like withdrawal symptoms and sleeplessness.

Question 9

Monitoring

Answer 9

Symptoms should be reviewed 1–2 weeks after starting treatment and regularly thereafter. If no effect has been seen at 4 weeks, you should consider changing the dose or drug. Otherwise the dose should not be adjusted until after 6–8 weeks of therapy.