SAN DIEGO, May 8 (Reuters) - Wyeth's WYE.N experimental drug Pristiq alleviates symptoms of menopause such as hot flashes without a significant impact on sexual function, researchers said on Tuesday, but the degree of relief falls short of that seen with estrogen therapy.
Pristiq, an altered form of Wyeth’s top-selling anti-depressant Effexor, is awaiting U.S. Food and Drug Administration approval as a treatment for both hot flashes associated with menopause and depression in adults.
Trial results unveiled here at a meeting of the American College of Obstetricians and Gynecologists also showed that Pristiq helped with mood disturbances and sleep.
Wyeth expects to launch Pristiq as a treatment for hot flashes in the third quarter of this year. The new drug is expected to help fill the void in Wyeth’s sales that would emerge when Effexor loses its patent protection by 2010 and faces competition from cheaper generics.
A six-month trial involving 541 women suffering from moderate-to-severe hot flashes found that a 100 mg dose of Pristiq resulted in about a 60 percent reduction in symptoms after 12 weeks, compared with a drop of about 50 percent for women given a sugar pill. A 150 mg dose cut symptoms by 66 percent.
“You can get a 90 percent, or more, reduction in hot flashes with estrogens,” said Dr. Isaac Schiff, chief of obstetrics and gynecology at Massachusetts General Hospital in Boston. He was not involved in the Pristiq trials.
Wyeth is the maker of once-blockbuster hormone replacement therapy Premarin, sales of which have plummeted after hormone drugs were linked to a higher risk of breast cancer.
The high placebo effect seen in studies of Pristiq matches that seen in trials of hormone therapies, said study author Dr. David Archer, professor of obstetrics and gynecology at Eastern Virginia Medical School.
If approved, Pristiq would be the first non-hormonal treatment indicated for relief of vasomotor symptoms.
“For women who can’t take estrogens -- those with a history of breast cancer or who do not want to take estrogens for whatever reason -- this should be made available,” said Dr. Schiff.
An FDA decision on Pristiq was postponed to July after Wyeth decided to conduct trials aimed at reducing nausea by starting patients out at a lower 50 mg dose. A Wyeth spokeswoman said results from those trials will be presented at a medical meeting later this year.
Dr. Archer said side effects seen in the steady-dose trials of Pristiq included temporary nausea and dizziness.
Nausea “is thought to be due to giving a bigger dose initially,” he explained. As a result, the latest trials of the drug start patients out on a 50 mg dose before ratcheting up to 100 mg or 150 mg. The dosage is also tapered down when patients are taken off the drug, said Dr. Archer.
Pristiq, like Effexor, is a serotonin-norepinephrine reuptake inhibitor. Other common anti-depressants, like Pfizer’s Zoloft, are serotonin reuptake inhibitors.
As a dual reuptake inhibitor, the theory is that Pristiq would be a better option for depressed women who are transitioning through menopause and often are experiencing a fluctuation or decline in estrogen that may diminish both serotonin and norepinephrine functioning.
In addition, some anti-depressants have been associated with lower libido. A trial of Pristiq showed that a nonsignificant 4.2 percent of patients treated with the drug had problems like abnormal orgasm and decreased libido, compared with 1.3 percent of patients on placebo.
Wyeth is also studying Pristiq as a treatment for fibromyalgia, an under-treated chronic pain syndrome.
The drug will be manufactured at Wyeth’s Guayama, Puerto Rico, plant where the FDA is reinspecting the facilities to certify that past problems have been fixed.
((Reporting by Deena Beasley, editing by Richard Chang; Reuters Messaging: firstname.lastname@example.org@reuters.net; 1-213-955-6746)) Keywords: WYETH PRISTIQ
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