Choice and safety of antidepressants in medical comorbidity

What it is

When depression sits alongside another medical condition, the choice of antidepressant turns on that other condition as well as on the depression. The options are the selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, atypical antidepressants, tricyclic antidepressants, electroconvulsive therapy (ECT), and psychotherapy. In older patients these are the same options as in younger patients; what differs is the dose and the care taken over side effects.

How it is treated

After myocardial infarction, SSRIs are the safest and probably more effective than the other classes in patients with a history of myocardial infarction. Sertraline has been shown to be the best choice among the SSRIs in these patients, though other medications can still be used.

In IBS, tricyclic antidepressants as low-dose amitriptyline, 10-30 mg, are preferred in IBS-D, while SSRIs are preferred in IBS-C, both for IBS symptoms.

In chronic tension-type headache, amitriptyline may reduce headache duration and severity compared with placebo. SSRIs have no proven benefit for headache prophylaxis over placebo or over tricyclic antidepressants in patients with chronic daily headaches.

In painful diabetic peripheral neuropathy the antidepressant is not the first drug: pregabalin is considered first-line therapy, with gabapentin as a first-line alternative, while venlafaxine and lidocaine 5% spray are considered second-line therapies.

In older patients, decreased metabolism and clearance rates mean smaller doses may be enough to achieve a therapeutic effect. The rule of thumb is to start low and go slow when titrating antidepressants in this population. Before a tricyclic is started the heart is checked. An ECG is the most important investigation before starting tricyclic antidepressants, especially in the elderly, in children, and in those with pre-existing cardiac diseases. The most common cardiac side effects of these drugs are prolongation of the PR, QRS and QT intervals, and that is what can lead to ventricular arrhythmias and death; arrhythmia is also the most common cause of death in overdose.