Efexor singled out in antidepressant safety review
pharmafile | December 7, 2004 | News story | |Â Â Â
A long-awaited investigation into the safety of modern antidepressants has concluded that the SSRI class of drugs is safe, but warnings are to be strengthened and monitoring of young adults on the drugs will be increased.
It is 18 months since the UK medicines regulator the MHRA first began its investigation into the drugs, prompted by growing evidence from patients taking Seroxat of increased suicidal thoughts and severe withdrawal symptoms.
To the surprise of many, the Committee on Safety of Medicine's expert working group concluded there were no significant differences in the safety and efficacy of the SSRI drugs, but did single out Wyeth's Efexor, an antidepressant with a slightly different mode of action.
The group has recommended the drug should only be started by specialists such as psychiatrists, a conclusion largely based on UK data which shows the drug has been associated with a higher rate of deaths from overdose than SSRIs.
It also recommended that patients with heart disease should not be given the drug at all because of evidence suggesting it may affect cardiac function. Finally, the committee pointed out that along with GSK's Seroxat (paroxetine) it was more likely to cause withdrawal reactions than the other drugs.
Wyeth UK was quick to defend the reputation of the drug, claiming that Efexor was prescribed to patients with more risk factors for suicide, and that this was the reason behind the greater number of fatal overdoses.
The company said the more severe condition of these patients was not unexpected as Efexor is often used when other agents (SSRIs, and older tricyclics, known as TCAs) have been ineffective.
Wyeth says the MHRA's GPRD database shows these patients had a higher incidence of prior hospitalisations for depression, schizophrenia along with depression, failure to respond to other antidepressants, and suicidal behaviour in the preceding year. It added that the scale of these risk factors was "strikingly similar" to the different rates of fatal overdose observed.
Wyeth's UK medical director said: "The MHRA's conclusions fail to account for these critical data. Restricting access to medication is not in the best interest of patients, and is a backward step in the treatment of depression in this country.
"In the UK, many of the nearly 300,000 Efexor patients have failed on one or more other antidepressants. The MHRA's action may lead to the increased use of less appropriate medications such as TCAs that have a long history of safety concerns including a higher risk of fatal overdose, suicide, and disruptions of cardiac rhythm at therapeutic doses.
Wyeth says this will "needlessly place restrictions" on the use of Efexor and has vowed to challenge the decision.
The company says the new restrictions will place an "unnecessary burden" on specialists and could be detrimental to patients, the government's own figures showing that 10,000 UK mental health patients waited 17 weeks before seeing a psychiatrist.
Figures from Infopharm show unit sales of Seroxat fell 18% in the 12 months to August 2004, part of an ongoing decline in prescribing of the drug since 2002 when fears about its safety began to mount.
Sales in the SSRI class overall grew 7% in the same period, with Efexor sales rising 22%. Wyeth's drug is likely to experience an even more rapid fall in sales when prescribers implement the new guidance.
For a comprehensive review of the new MHRA guidance on the antidepressants, visit www.pharmafocus.com and January's edition of Pharmafocus.
