People who take a class of older anti-depressant drugs have an increased risk of heart disease, scientists said on Wednesday, but the risk is not increased with newer selective serotonin reuptake inhibitors (SSRI).
In a study of almost 15,000 people in Scotland, British researchers found that older so-called tricyclic anti-depressants, such as Norpramin made by Sanofi-Aventis, were linked with a 35 percent increased risk of developing cardiovascular disease.
"Given that anti-depressants, such as SSRIs, are now prescribed not only for depression but for a wide range of conditions such as back pain, headache, anxiety and sleeping problems, the risks associated with anti-depressants have increasing relevance to the general population," said Mark Hamer of University College London, who led the study.
Hamer said that while the older class of drugs had largely been overtaken in the treatment of depression by newer SSRIs such as Eli Lilly's Prozac or GlaxoSmithKline's Paxil, tricyclics are still commonly used to treat conditions such as insomnia, back pain and severe headaches.
"Our findings suggest doctors should be cautious about prescribing anti-depressants," he said in a telephone interview.
The generic drugs amitriptyline, sold under the brand names Elavil, Tryptizol, Laroxyl, and clomipramine, known under the brand name as Anafranil, are also commonly used tricyclics.
Amy Thompson, a senior cardiac nurse at the British Heart Foundation charity, said the results of the study should be viewed with caution and said further studies were needed
"Before firm conclusions can be drawn there needs to be more research looking closely at the effects of these drugs on your heart," she said. "Anti-depressants are beneficial for many people and so it would be unwise for anyone taking them to stop based on the results of this study alone."
Hamer's team used data from the Scottish Health Survey, which collects information from the general population every three to five years. They combined data from 1995, 1998 and 2003 in adults aged over 35, linked them with records on hospital admissions and deaths and tracked them until 2007. Those with a clinical history of heart disease were excluded from the study.
During an average of eight years follow-up, there were 1,434 events related to heart disease, of which 26.2 percent were fatal, the researchers reported in the European Heart Journal.
Among the study participants, tricyclic anti-depressants, SSRIs or other antidepressants were used by 2.2 percent, 2.0 percent and 0.7 percent, respectively.
After adjusting for confounding factors, the researchers found there was a 35 percent increased risk of cardiovascular disease linked with tricyclic anti-depressants. The use of SSRIs was not linked to any increased heart disease risk.
"This suggests that there may be some characteristic of tricyclics that is raising the risk," Hamer said. "Tricyclics are known to have a number of side effects — they are linked to increased blood pressure, weight gain and diabetes, and these are all risk factors for cardiovascular disease."
He too said it was important that patients already taking anti-depressants should not suddenly stop taking their medication, but should consult their doctor.