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Guanfacine Does More Damage Than Good

Discussion in 'Medications & Substances' started by No-Twitch-Tabitha, Feb 20, 2007.

  1. No-Twitch-Tabitha

    No-Twitch-Tabitha New Member

    [URL="http://www.womenshealth.gov/news/english/536351.htm"][/URL]A drug long used to treat post-traumatic stress disorder appears to have done patients no good and may even have done some harm. In the first-ever randomized, placebo-controlled trial of guanfacine for the alleviation of post-traumatic stress disorder (PTSD), "we found that it really offered patients no benefits of any symptoms, and we looked at a lot of symptoms," said lead researcher Dr. Thomas Neylan, medical director of the PTSD treatment program at the San Francisco VA Medical Center.

    "We looked at whether people were feeling less anxious, whether they were sleeping better, whether they startled less, whether they were having fewer intrusive memories," said Neylan, who is also an associate professor of psychiatry at the University of California, San Francisco. "But in anything that we looked at, we found there was no benefit for the drug over placebo."

    The study results may come as a surprise to psychiatrists and patients, since guanfacine and a related drug, clonidine, have been used for years to treat PTSD. "They are commonly used, but what we hope now is that people shy away from using clonidine and guanfacine," Neylan said. One expert said he was taken aback by the findings.

    "I was so shocked that I had to think about it for two days. I was trying to find a hole in the science and I can't -- this is a state-of-the-art clinical trial," said Dr. Randall Marshall, director of Trauma Studies and Services at New York State Psychiatric Institute. "Their effect size was zero -- there's no hint of a benefit."

    The study, which was funded by the U.S. Department of Veterans Affairs, is published in the Dec. 1 issue of the American Journal of Psychiatry. Guanfacine's rise and apparent fall as a PTSD treatment may be an object lesson in why randomized, controlled trials -- such as the one Neylan's group conducted -- are so important to assessing a drug's worth, he said.

    Guanfacine and clonidine are alpha-2 agonists, which means they bind to the alpha-2 receptor on brain cells, blocking the release of a neurotransmitter called norepinephrine, Neylan explained. Norepinephrine is the neural form of the stress hormone adrenalin. Psychiatrists have long known that PTSD patients have increased levels of norepinephrine activity in their brains.

    "So, from the start, the whole idea was very appealing -- you give a drug like guanfacine that blocks the effects of norepinephrine, and you'd hope to see some benefit," he said. "It made intuitive sense. It was a lovely idea." In fact, it was such an attractive idea that more than 20 review articles and guidelines, published in a variety of psychiatric journals, touted the use of guanfacine and clonidine in easing PTSD symptoms.

    But no one had ever put this idea to the test in a randomized, controlled trial. In its eight-week study, Neylan's group compared the effects of guanfacine and an identical-looking placebo pill in 63 male and female veterans diagnosed with PTSD. Twenty-nine participants were randomly picked to take guanfacine while the other 34 took the dummy pill.

    By the end of the study, the researchers found no net difference between the two groups in terms of changes in symptoms. "But the one thing that did clearly come out was that there were more side effects with guanfacine," Neylan said. "There was more sedation, feeling fatigued, dry mouth."

    Why did a pill that should have worked so well in theory fall flat in practice? Neylan offered one possible answer. "[Too much] norepinephrine can be a bad thing," he noted, "but you also need it for your brain to work well. So, lowering the whole pool of norepinephrine did not seem to be an effective strategy."

    He said the relatively small sample size in the study means he can't be absolutely certain that alpha-2 agonists have no benefit, "but we did get a zero effect size. That means that even if we had 5 or 6 times this sample, the probability of showing a meaningful difference is really, really low."

    Marshall agreed that the methodology is sound, and the findings conclusive. "I think this pretty much answers the question of whether, in this population, guanfacine should be considered as either a primary or an adjunctive treatment. The answer is no -- it's a big surprise," he said.

    The finding will change the way he and psychiatrists everywhere treat PTSD patients, said Marshall, who is also associate director of the Anxiety Disorders Clinic and an associate professor of clinical psychiatry at the Columbia University College of Physicians and Surgeons. He believes that, despite the anecdotal success of guanfacine in isolated cases, "We should not generalize that to PTSD or treatment-refractory PTSD."

    Neylan said a newer drug that works on norepinephrine receptors, but in a different way, might still succeed where guanfacine has failed. That drug, called prazosin, blocks the alpha-1 receptor in the synapse. "There have been a few trials to show that prazosin does have some promise, and I know the VA is gearing up to do a large multi-site study. It is becoming more popular."

    In the meantime, he said, it's important to remember that the first-line therapy for most people with PTSD is antidepressants and/or psychotherapy, especially "exposure therapy," where patients are gently confronted with reminders of the traumatic event itself. "Most people feel that PTSD benefits most from a combination of pharmacologic treatment and psychotherapy," Neylan said.
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