Drug selection
The discussion around taking antidepressants should include the risks of adverse effects, including side effects, possible discontinuation symptoms, interactions with other medication and the potential impact on any existing physical illness. Previous use of an antidepressant and its effect may also guide the selection.12
Generic selective serotonin re-uptake inhibitors (SSRI) are the first line option due to efficacy and a favourable risk-benefit ratio. However, SSRIs may increase bleeding, meaning a gastro-protective medicine may be necessary for older people already taking an NSAID or aspirin. Elderly patients taking antidepressants, especially SSRIs, are also at increased risk of hyponatraemia.12,14
Fluoxetine, fluvoxamine and paroxetine also are more likely to cause side effects compared to other SSRIs, and paroxetine has a higher incidence of discontinuation symptoms.12
Toxicity should also be considered. In primary care, venlafaxine is associated with the greatest risk from overdose, while tricyclic antidepressants (TCAs), except for lofepramine, are associated with the greatest risk in overdose.
Venlafaxine may exacerbate cardiac arrhythmia and may require regular blood pressure monitoring. Venlafaxine taken with duloxetine is also associated with hypertension, while TCAs have the potential to cause postural hypotension and arrythmias. Elderly people taking mianserin should be monitored with blood tests.
Use of mono-amine oxidase inhibitors (MAOIs) such as phenelzine should normally only be initiated by a specialist.