In this study, a case is presented in which initiation of an antidepressant drug was associated with an episode of extreme sedation. This case provides an opportunity to highlight possible pitfalls in geriatric prescribing.
Coupland et al. [
A 92-year-old man was admitted to hospital with a general decline in functional status. A comprehensive geriatric assessment revealed low mood without evidence of cognitive impairment, and a diagnosis of depression was made. The patient was prescribed mirtazapine 7.5 mg nocte per oral, and the following day, he became increasingly unstable. Two days later, the patient was found unresponsive in bed.
There was no history of head trauma, and no seizure activity was observed. Vital signs were unremarkable, while respiratory, cardiovascular, and abdominal examinations were normal. However, neurological examination revealed diminished mental status. The patient did respond to a deep, painful stimulus but his eyes remained closed, and there was no verbal response. The patient had brisk deep tendon reflexes and showed plantar reflexes of the extensor. Blood tests (including those for urea, electrolytes, glucose, calcium, magnesium, Vitamin B12 and folate levels, C-reactive protein, thyroid function, and full blood count) were normal. An electrocardiogram displayed normal sinus rhythm, and an emergency magnetic resonance brain scan demonstrated no evidence of acute intracranial pathology.
The patient’s level of consciousness gradually returned to normal after 4 hours. The antidepressant-induced sedation was suspected of being the cause, and mirtazapine was immediately stopped. There was no subjective improvement in mood after withdrawal of mirtazapine. Three days later, the patient was re-prescribed on mirtazapine 3.75 mg nocte. Though he appeared expressionless, he gradually became more responsive after a week. Following the reduction of mirtazapine dose, the patient did not experience any more episodes of extreme sedation during a 2-month follow-up.
This case is a teaching example of antidepressant-induced extreme sedation in a geriatric prescription for depression. Depression is the most common mental health disorder with life-threatening consequences and affects up to 13.3% of the elderly population [
According to the NHS Grampian Guidance for Initiating Antidepressants, which was developed according to guidance by the National Institute for Health and Care Excellence, mirtazapine and sertraline are both first-line treatments for depression in older people [
Sertraline is another antidepressant that can also cause drowsiness [
Prescribing for older patients presents unique challenges because the elderly are often more sensitive to drugs and therefore are at increased risk of experiencing adverse effects. This is due to the pharmacokinetic and pharmacodynamic changes that occur with aging, including increased body fat composition, decreased lean mass, decreased P450 enzyme system activity, decreased renal excretion of drugs, and increased sensitivity to the effects of drugs. These factors are especially important when the drug involved has a narrow therapeutic range, which is the case with antidepressants [
Furthermore, adverse drug reactions commonly lead to hospital admission in the elderly [
Prescription of potentially inappropriate and excessive medications in older people is common. A review article by Gallagher et al. [
Additional discussion would be needed in elderly patients as follows. Many patients with depression who do not respond adequately to standard treatment with pharmacotherapy and psychotherapy are candidates for noninvasive neuromodulation procedures, including transcranial magnetic stimulation (TMS) and electroconvulsive therapy (ECT) [
Despite the effectiveness of pharmacological treatments in depression, symptom remission has been achieved in fewer than 40% of elderly patients of depression with cognitive impairment, with or without dementia [
The author declares that there are no conflicts of interest regarding the publication of this paper.