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zoom RSS 新世代向精神薬の小児に対する副作用/米国医療事情

<<   作成日時 : 2008/09/18 19:25   >>

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 月曜日に出版された新たな政府の研究で、最もしばしば小児と思春期の子供の統合失調症に処方された薬が、古くからある安価な薬よりも効果的でなく、いくつかの有害な副作用をより起こしそうであるとわかった。
 約100万人の小児の統合失調症に対する治療の変更が迫られる。非定型向精神薬と呼ばれる新世代の薬剤処方量は過去数十年で5倍となり、重大な副作用があるにも関わらず、多種多様な診断の下、暴発や強暴性を落ち着かせるために処方されている。州メディケイド連合により適切な小児への使用法を評価している。
 研究により新しい向精神薬(イーライ・リリーのZyprexaとヤンセンのRisperdal)の2つをより古い医薬品と比較し、すべてが多くの若い患者の幻聴のような統合失調症の症状を軽減するとわかった。しかし半数は効果がないか体重増加のような重大な副作用を起こしたため服用を止めた。Zyprexa は著明な体重増加を引きおこしたため、政府の安全監視委員会が中止命令を出した。
 国立精神衛生研究所NIMHによる資金提供を受けた長い間結果待ちされた研究であった。米国では約300万人の患者がおり、40%は10代かさらに前から症状が現れる。
 ノース・カロライナ大での8-19才の119人の精神疾患の患者に、Zyprexa、Risperdal またはmolindone(モリンドン:古い薬)の3種類を投与した。8週間の投与で、改善率はそれぞれ、34%,46%,50% であった。しかし多くは途中で服薬を止めたので、有意差が出なかった。多くが体重増加し、Zyprexaで13ポンド、Risperdalで約9ポンド増加し、コレステロールとインスリンが変化したが、molindoneでは1ポンドの増加で代謝変化はわずかだった。
 イーライ・リリーとヤンセンのスポークスマンは、彼らの薬が、子供の統合失調症の治療のために認可されてはいないとしている。さらに、8週間では、古い薬に関連したやっかいな副作用であるパ−キンソン様の運動症状を見るのに不充分であると指摘している。この副作用のためにモリンドン服用患者は別の薬に切り替え、1990年代に多くが新薬に代わった。
 2005年に出された成人での新旧薬剤比較試験で同様の体重増加問題が起きている。しかし、急速に新薬が広まったのは、より安全で効果的だったということだろうと、Dr. McClellanは言う。
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小児向精神薬治療研究での問題/米国
http://kurie.at.webry.info/200806/article_17.html
小児への向精神薬使用量の増加
http://kurie.at.webry.info/200805/article_9.html
小児の双極性障害(躁うつ病)の爆発的な増加/米国医療事情
http://kurie.at.webry.info/200709/article_8.html
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Risks Found for Youths in New Antipsychotics
http://www.nytimes.com/2008/09/15/health/research/15drug.html
By BENEDICT CAREY
Published: September 15, 2008
画像A new government study published Monday has found that the medicines most often prescribed for schizophrenia in children and adolescents are no more effective than older, less expensive drugs and are more likely to cause some harmful side effects. The standards for treating the disorder should be changed to include some older medications that have fallen out of use, the study’s authors said.

The results, being published online by The American Journal of Psychiatry, are likely to alter treatment for an estimated one million children and teenagers with schizophrenia and to intensify a broader controversy in child psychiatry over the newer medications, experts said.

Prescription rates for the newer drugs, called atypical antipsychotics, have increased more than fivefold for children over the past decades and a half, and doctors now use them to settle outbursts and aggression in children with a wide variety of diagnoses, despite serious side effects.

A consortium of state Medicaid directors is currently evaluating the use of these drugs in children on state Medicaid rolls, to ensure they are being prescribed properly.

The study compared two of the newer antipsychotics, Zyprexa from Eli Lilly and Risperdal from Janssen, with an older medication and found that all three relieved symptoms of schizophrenia, like auditory hallucinations, in many young patients. Yet half of the children in the study stopped taking their drug within two months, either because it had no effect or was causing serious side effects, like rapid weight gain. The children receiving Zyprexa gained so much weight that a government oversight panel monitoring safety ordered that they be taken off the drug.

The long-anticipated study, financed by the National Institute of Mental Health, is the most rigorous, head-to-head trial of the drugs in children and adolescents with this disorder. About three million Americans suffer from schizophrenia, and perhaps 40 percent first show symptoms in their teens or earlier.

“This is really a landmark study, because these newer drugs have been around for 12 years or so now, and there were fundamental questions for which we really didn’t have answers,” said Dr. Sanjiv Kumra, director of the division of child and adolescent psychiatry at the University of Minnesota, who was not involved in the study.

Dr. Kumra said the results revealed significant differences in the drugs’ side effects that should help doctors and patients choose among them.

“What this is saying is that all treatments work, at least for some people, and have serious risks for others,” he said. “It’s a trial-and-error process” to match people with the right medication.

Dr. Jon McClellan of the University of Washington, a co-author of the new study and of the current guidelines for treating childhood schizophrenia, said in a telephone interview that older schizophrenia drugs should now be considered as an alternative in some cases.

“Some of the children in this study gained 15 pounds or more in eight weeks,” Dr. McClellan said. “That’s as much as adults gain in a year on these medications. Children are especially susceptible to these side effects, and this has broad implications across the board, for the use of these agents to treat any disorder.”

Studies have found that more than 80 percent of prescriptions for atypical antipsychotics for children are to treat something other than schizophrenia, like autism-related aggression, bipolar disorder or attention-deficit problems. Some of these are approved uses; others are not.

The researchers, led by Dr. Linmarie Sikich of the University of North Carolina, recruited 119 young people, ages 8 to 19, who suffer from psychotic symptoms. The children received either Zyprexa, Risperdal or molindone, an older drug used to blunt psychosis. Neither the young patients nor the doctors treating them knew which drug was being taken, but the researchers told the youngsters and their parents that, if the medication was not working out, the family could switch to another one.

After eight weeks, 34 percent of the children taking Zyprexa, 46 percent of those on Risperdal, and 50 percent of those receiving molindone showed significant improvement.

But by that time so many of the patients had stopped taking the drug they were on that it was not clear that those differences were significant. Many had gained a lot of weight: an average of about nine pounds for those in the Risperdal group, and 13 pounds in the Zyprexa group.

Both groups also showed changes in cholesterol and insulin levels that are risk factors for diabetes. Those taking molindone gained less than a pound, on average, and had little metabolic changes.

“I thought the extra weight was putting a lot of pressure on me,” said Brandon Constantineau, 18, a study participant in Wilmington, N.C., who gained 35 pounds while taking Risperdal for several months. “Kids at school were making fun of me, all that. I knew I had to get rid of it. I exercised a lot, but it didn’t happen until I changed drugs.”

Mr. Constantineau said he was now doing well on a medication not offered in the study.

Dr. Sikich, the study’s lead researcher, said, “One implication of this study is that the guidelines for treating schizophrenia need to be revised, so that some of the milder, traditional or older medications are considered first-line treatments in some cases.” She added: “The other significant thing is that none of these medications were as well tolerated as we had hoped. We really need to find better alternatives.”

Spokesmen for Eli Lilly and Janssen said that their drugs were not approved to treat schizophrenia in children and that, given the limited number of options for such patients, there was a need for new therapies.

Jamaison Schuler, a spokesman for Eli Lilly, pointed out that the new study, at eight weeks in length, had not lasted long enough to pick up the most worrisome side effect associated with the older drugs: Parkinson’s-like movement problems, which are often irreversible. Patients in the study taking molindone also took another drug to reduce this risk.

Beginning in the early 1990s, psychiatrists turned to the newer drugs in large part to spare their patients those problems. Several large studies since then have shown that that shift ― while perhaps sparing some patients movement problems ― has had a cost.

A landmark comparison of older and newer drug in adults with schizophrenia, published in 2005, had findings similar to the new report. Most patients in the earlier study stopped taking the drug they were put on, and some of the medications were associated with rapid weight gain and other problems.

“I think the reason the use of these newer drugs has gone up so fast is that there was this widespread assumption that they were safer and more effective than what we had before,” Dr. McClellan said. “Well, we’re seeing now that that’s not the whole story.”

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