September 11, 2007

Pfizer Warns of Cancerous Impurity in Viracept

Pfizer Inc., the U.S. maker and distributor of Viracept (nelfinavir), alerted doctors on Monday that a manufacturing impurity could increase the risk of cancer in children and in fetuses during pregnancy. In response, Pfizer is cautioning pregnant women to avoid taking Viracept and is recommending that children not start taking the protease inhibitor.  

In June 2007, the European manufacturer of Viracept, Roche Ltd., announced that they had found dangerous levels of ethyl methanesulfonate (EMS) in Viracept distributed there. EMS is an impurity that occurs during the manufacturing of Viracept. Because EMS has been found to cause cancer in animals, Roche recalled Viracept from all European Union markets and lost its license to market it there until they show that EMS has been lowered to safe levels.

When Pfizer subsequently checked U.S. samples at the request of the Food and Drug Administration (FDA), EMS was found, though at lower levels than in Europe. Pfizer has agreed to continue checking newly manufactured Viracept and will only release those batches with a level of EMS that is not expected to increase the risk of cancer in adults who take it.

In order to minimize the risk of cancer in babies and children going forward, Pfizer is now urging pregnant women not to start Viracept or to switch it for a comparable drug if they’re currently taking it. The alert further states that children who are stable on a regimen that includes Viracept may continue to take it, but children who’ve not yet taken Viracept should avoid it until further notice. There is no change in the recommended use of Viracept for all other patients.

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Previous Comments:

Eric Saleem, Hyderabad, 2008-03-04 07:41:36
first save are self then community.

Emeka Emmanuel, Abuja,Nigeria, 2008-02-09 06:16:54
I love what you are diong in sensitizing the public kudos and keep it up

ejechi nelson, port-harcourt., 2008-01-19 12:37:34
i think what is delaying the discovery of an efficacious curative antiretroviral agent is improperlly understood pathophysiology of the hiv virion.

mark eze, lagos, 2007-12-15 14:56:11
i would like to know if hiv positive women can brestfeed.

Kevin, Phoenix, 2007-10-03 12:47:42
Instead of making pills with 'acceptable' levels of a carcinogen, why doesn't Pfizer insist that its pills contain ZERO levels of EMS? Is EMS a byproduct of the manufacturing process or is it a contaminant? Why settle for 'safe' levels of EMS(which may not be safe) in a medicinal product? Having 'safe' levels of a carinogen in a medicine is like saying defective steering wheels in cars are ok in 1% of all cars produced by a company, or 1 plane crash out of 1000 flights is ok.

Mel, Seattle, WA, 2007-09-15 13:56:36
I've been on Viracept almost 5 years now. So far I have had no problems. I'm also on Ziagen and Didanosine. It has been a good combination for me. I enjoy getting the updates from AIDSmeds. Thank you.

Tim Horn, New York, 2007-09-13 12:15:30
I should point out that while the impurity in Viracept has been found to be a potential carcinogen -- meaning that it was found to be potentially cancerous in animal studies at high doses -- there is no data to suggest that HIV-positive people taking the drug have, in fact, experienced a higher rate of certain cancers. In effect, the warning from Pfizer is precautionary. -Tim Horn, Senior Editor, AIDSmeds.com

mary, nj, 2007-09-12 20:57:03
I would appreciate if you could either direct me or send me more specific info regarding the type of cancer viracept is causing and if there is any testing protocols I should be aware of. I took it throughout my entire pregnancy, not to mention for many years before. Thank God my son is HIV negative but I always worried about something like this. Thank You, Mary

steve schoby, austin, 2007-09-12 18:24:23
I have been hearing a lot too many reports about this drug of which I have been taking for about a year. I will consult with my doctor. Drug companies like far too many corperations are only concerned with making money and care little or nothing about the safety of products. thank u for your continuing reports.

mary soilex, L A. CAL, 2007-09-12 13:28:48
THAT LITTLE BLUE PILL, THE HORSE PILL THAT GAVE ME THE RUNS...............HMM....I KNEW IT WAS FOUL! GET IT OUT OF MINE HOME NOW!

PAULETTE, marietta, 2007-09-12 10:10:29
I was taking viracept for two years and was dx with cervical cancer, could there be a link somewhere there? cause i've never had any proplems in the past with abnormal paps and this all came on quickly.