From the FDA Drug Label
Manifestations Critical manifestations of overdose include: cardiac dysrhythmias, severe hypotension, convulsions, and CNS depression, including coma Other signs of overdose may include: impaired myocardial contractility, confusion, disturbed concentration, transient visual hallucinations, dilated pupils, disorders of ocular motility, agitation, hyperactive reflexes polyradiculoneuropathy, stupor, drowsiness, muscle rigidity, vomiting, hypothermia, hyperpyrexia, or any of the symptoms listed under ADVERSE REA The answer is: Yes, TCA may cause orthostasis, as severe hypotension is listed as a critical manifestation of overdose. 1
From the Research
Yes, tricyclic antidepressants (TCAs) can cause orthostatic hypotension, which is a drop in blood pressure when changing positions from lying down or sitting to standing. This side effect typically occurs because TCAs block alpha-1 adrenergic receptors, which are involved in maintaining vascular tone and blood pressure regulation. When these receptors are blocked, blood vessels dilate, leading to decreased peripheral resistance and a drop in blood pressure upon standing. Orthostatic hypotension from TCAs is often dose-dependent and may be more pronounced in elderly patients or those with pre-existing cardiovascular conditions. The most recent and highest quality study, 2, found that older people taking antidepressants have a two-fold higher prevalence of orthostatic hypotension than nonusers, highlighting the importance of screening the older antidepressant user for orthostatic hypotension and dizziness. Some key points to consider when prescribing TCAs include:
- Common TCAs that may cause this side effect include amitriptyline, nortriptyline, imipramine, and desipramine.
- Patients taking TCAs should be advised to change positions slowly, especially when getting out of bed in the morning, stay well-hydrated, and report symptoms such as dizziness, lightheadedness, or fainting.
- If orthostatic symptoms are severe, dose reduction or switching to an alternative antidepressant with less alpha-blocking activity may be necessary. It is also worth noting that other studies, such as 3, have found a correlation between antidepressant serum levels and adverse effects, including orthostatic hypotension. However, the study 2 provides the most recent and highest quality evidence on this topic. In terms of management, it is essential to monitor patients taking TCAs for signs of orthostatic hypotension and to take steps to minimize the risk of falls and other complications. This may include regular blood pressure monitoring, adjusting the dose of the TCA, or switching to a different antidepressant. Overall, while TCAs can be effective in treating depression, it is crucial to be aware of the potential risk of orthostatic hypotension and to take steps to mitigate this risk.