Some widely prescribed antidepressants may not be as safe for elderly patients as other classes of drugs, according to a study recently published in the British Medical Journal.
In a population-based cohort study of patients aged 65 and older, researchers found that those taking selective serotonin reuptake inhibitors (SSRIs) — the class of antidepressants that includes popular drugs like Prozac, Celexa and Zoloft — were more likely to suffer adverse effects than people not taking the medications. Those on SSRIs were more likely to die, have a stroke, suffer falls, fracture bones and have seizures.
The study also found significantly more adverse outcomes associated with SSRIs than with an older class of medications known as tricyclic antidepressants.
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However, the relative benefits of these drugs — a factor that was not captured by the study — need to be considered along with the risks when deciding which medication to prescribe for older patients, the authors said.
There is still much that is unknown about the adverse effects of antidepressants in this age group because seniors tend to be underrepresented in clinical trials of the drugs, and most trials are short-term. Elderly patients with depression also tend to have co-existing medical conditions and many take other drugs; they may also be more sensitive to drug side effects than younger patients.
In the current study, researchers led by Carol Coupland, an associate professor of medical statistics at the University of Nottingham, looked at prescription data on 60,746 patients aged 65 to 100 years who were newly diagnosed with depression between 1996 and 2007. Many patients had other conditions, such as heart disease and diabetes, and were taking several medications. The patients were followed for an average of five years.
About nine out of 10 patients received at least prescription for an antidepressant during the follow-up period: most (55%) were prescribed an SSRI; about one-third (32%) got a prescription for a tricyclic antidepressant; and about 14% were prescribed other drugs like Remeron (mirtazapine) and Effexor (venlafaxine hydrochloride).
Compared with no antidepressant use, the use of any antidepressant was associated with higher risks of adverse outcomes. SSRIs, however, appeared to carry more risks than tricyclics: compared with patients taking the older class of drug, those taking SSRIs were 15% more likely to have a stroke, 26% more likely to suffer a fracture, and 80% more likely to have a seizure. Over the course of a year, 8% of patients on tricyclic antidepressants died, compared with nearly 11% of those on SSRIs and 7% of patients not taking any antidepressant.
Notably, patients prescribed other classes of antidepressants (including Remeron and Effexor) had still higher risk of adverse outcomes, including suicide risk and death, compared with those not taking a drug for depression and with those taking tricyclics.
The study authors said that the risks were greatest during the first 28 days of starting an antidepressant and the first 28 days after stopping.
One important limitation of the findings was that tricyclic antidepressants were typically prescribed in lower doses than SSRIs, which could account for some of the reduction in risk associated with the drugs. The study also did not follow people who took SSRIs over the long term.
“The choice of class of antidepressant is a complex decision, and some evidence is still lacking to help with that choice in older patients,” Coupland told HealthDay. “Low-dose [tricyclic antidepressants] may be more suitable in frail elderly patients at increased risk of falls and fracture.”
Still, the findings do not suggest that SSRIs should be avoided by older patients. Rather, they are a good reminder that physicians should monitor elderly patients carefully, particularly during their first month of treatment with antidepressants and during the first month after discontinuing therapy.