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Tens of thousands of New Zealanders are swallowing antidepressant pills that don't work, a groundbreaking study shows.
The study - one of the largest into popular drugs, including Prozac - has found the pills have no "clinically significant" effect.
However, some experts were today continuing to back the drugs if they are prescribed to the right people.
The results showed the drugs increased patients' scores on a 51-point depression scale by an average of only two points, although the study reported the drugs had a more significant effect on patients with severe depression.
And it suggested "talking treatments" should replace drug treatments for clinically depressed people.
The drugs were prescribed more than 700,000 times in New Zealand last year at a cost of almost $28 million.
The medical director of the drug-buying agency Pharmac, Dr Peter Moodie, last night said the study included "some very interesting data", and would be discussed by the agency's clinical committees.
But Pharmac would not rush a decision on the findings.
"When we're looking at questions about the efficacy of drugs, we should use a measured approach."
Researched Medicines Industry Association chairwoman Dr Pippa MacKay said today anti-depressants could have a transforming effect for patients.
"Yes, they certainly do work and I guess that the trick is prescribing them to the right people," said Dr MacKay, a Christchurch GP.
The drugs in the study are a modern type of antidepressant called selective serotonin re-uptake inhibitors (SSRI).
The most widely used in New Zealand are Fluox (formerly known as Prozac) and Loxamine.
The study was led by the University of Hull in England, and published yesterday in the online journal Public Library of Science.
Professor Irving Kirsch, from the University of Hull, said: "Given these results, there seems to be little reason to prescribe antidepressent medication to any but the most severely clinically depressed patients."
Auckland University Professor of Health Psychology Keith Petrie said the study had been properly done, and its findings were important.
But he cautioned against applying averaged results to individual cases. The study did report excellent results for some patients, he said.
Britiain's Health Secretary, Alan Johnson, last year said his Government would spend £170 million ($413 million) over the next three years on training therapists in "talking treatments" to replace drugs.
A Ministry of Health spokeswoman said yesterday there were no immediate plans for a similar approach to be introduced in New Zealand.
The ministry did not plan to change advice it gave on depression treatment as a result of the review.
"There is a substantial body of evidence for the effectiveness of antidepressant drugs, especially for those with moderate to severe depression.
"The ministry would like to reassure those who are taking these drugs that they can be very helpful."
The recently retired chairman of the New Zealand national committee of the Royal Australia New Zealand College of Psychiatrists, Dr Allen Fraser, said yesterday the drugs were badly represented by the study.
Less than 10 per cent of patients were deemed suitable for trials, and the trials lasted less than six weeks.
Treatment for depression usually lasted at least six months, and patients generally showed steady improvements throughout that time.
"I think that when [antidepressants] are used for people with a significant depression, these medications are essential," Dr Fraser said. "They are not just good, they are essential."
But there were valid grounds for suggesting that less severely depressed people have non-medicated treatment initially.
The New Zealand distributor of Fluox, Pacific Pharmaceuticals, was approached for comment yesterday but did not respond. Eli Lilly, makers of Prozac, told the Independent newspaper in London that "extensive scientific and medical experience has demonstrated that fluoxetine (Prozac) is an effective antidepressant".
New Zealanders spent $28 million on SSRI antidepressants last year
There were 720,000 prescriptions
The most widely prescribed were fluoxetine (was Prozac, now Fluox), paroxetine (was Aropax, now Loxamine) and citalopram (Celapram).
A new study shows they have no "clinically significant" effect
- with NZPA