GlaxoSmithKline, a leading drugs manufacturer, was last week forced to admit
that paroxetine, a widely prescribed antidepressant and the company's
best selling drug, can cause severe withdrawal symptoms when
stopped.
The Food and Drug Administration in the United States published a new product
warning about the drug, and in the same week the International
Federation of Pharmaceutical Manufacturers Associations declared the
company guilty of misleading the public about paroxetine on US
television a year ago.
"This drug has been promoted for years as safe and easy to discontinue," said
Charles Medawar, head of Social Audit, a consumer research group
specialising in medicines policy. "The fact that it can cause
intolerable withdrawal symptoms of the kind that could lead to
dependence is enormously important to patients, doctors, investors,
and the company.
"GlaxoSmithKline has evaded the issue since it was granted a licence for
paroxetine over 10 years ago, and the drug has become a
blockbuster for them, generating about a tenth of their entire
revenue. The company has been promoting paroxetine directly to
consumers as `non-habit forming' for far too long."
Mr Medawar lodged a complaint a year ago after a spokesman from
GlaxoWellcome, then a UK company, described withdrawal symptoms with
paroxetine as "very rare" during an appearance on an American
television network. The spokesman added "[withdrawal] occurs in
only two out of every 1000 patients . . . Even then
the symptoms are mild and short lived."
In fact, withdrawal symptoms such as bad dreams, paraesthesia, and dizziness
occur in up to 7% of patients, according to the new product
information. The warning also mentions anecdotal reports of
agitation, sweating, and nausea and tells doctors to consider
restarting treatment if symptoms become intolerable.
The complaint was originally dismissed but went to appeal. On 18 January
the International Federation of Pharmaceutical Manufacturers
Associations announced that GlaxoSmithKline had breached two of
the industry's codes of practice. The federation ruled that the
spokesman's comments were promotional and were wrong.
Dr Peter Haddad, consultant psychiatrist for Salford's Mental Health Service
NHS Trust, welcomed the FDA's safety warning. He said: "Withdrawal
side effects from antidepressants are far commoner than many people
realise, and there's evidence that paroxetine has one of the highest
rates. In most cases the symptoms are mild, but in a minority they
are severe and prolonged
and treatable only by restarting the drug."
"There is also the danger of misdiagnosis and inappropriate investigation.
Severe dizziness can easily look like labyrinthitis. Patients should
be warned not to stop taking their antidepressants suddenly, and
doctors should taper the dose at the end of treatment, keeping a
close watch for withdrawal symptoms," Dr Haddad added.
He also called for discontinuation problems to be thoroughly assessed before
new antidepressant drugs are licensed. "This is a seriously
under-researched area. There's no good evidence to help doctors get
the dosing right as patients come off treatment. It's still a matter
of trial and error."
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