[Il est possible que le Viracept soit distribué par les programmes PEPFAR
dans les pays en développement. Pour rappel, l'AMM a été suspendue par
l'EMEA motivée par la contamination de certains lots par de
l'éthylmésilate, une substance génotoxique (voir e-med ci-dessous du 9
août), la FDA lance aussi une alerte. CB]
-----Message d'origine-----
la part de Leela McCullough
Envoyé : mardi 11 septembre 2007 18:57
india-drug@healthnet.org; procaare@healthnet.org
Viracept
E-DRUG: Pfizer, FDA warn of potential carcinogen impurity in Viracept
---------------------------------------------------------------------
[First Roche, now Pfizer... The Roche version of nelfinavir was withdrawn
globally; the Pfizer one not (yet). Although this is a product marketed in
USA, it would be important to know whether the Pfizer version has been
distributed through PEPFAR to developing countries. WB]
Pfizer And FDA Warn Of Potential Carcinogen Impurity In HIV Drug Viracept
11 Sep 2007
http://www.medicalnewstoday.com/articles/82050.php
Drug company Pfizer Inc together with the US Food and Drug Administration
(FDA) warned yesterday, Monday, that its HIV drug Viracept (nelfinavir
mesylate) may be contaminated with a potential carcinogen and asked doctors
not to start pregnant women or children on the drug.
Children who are already on the drug and are stable may continue to take
Viracept, but pregnant women should be switched to an alternative
antiretroviral said Pfizer and the FDA.
The drug company issued a Dear Healthcare Professional letter about the
presence of an impurity, ethyl methanesulfonate (EMS), that has entered the
Viracept formula during the manufacturing process. The letter also gives
guidelines on the use of Viracept in pediatric patients and pregnant women.
Although no human studies exist, EMS is considered a potential human
carcinogen: animal studies indicate it to be teratogenic (causing birth
defects), mutagenic (causing mutation through DNA damage) and carcinogenic
(causing cancer).
In the meantime the FDA has asked Pfizer to limit the amount of EMS in its
US Viracept products by re-engineering the manufacturing process to new
specifications.
The agency and the drug company have agreed that pediatric patients who are
stable on a drug regimen that contains Viracept may continue to take it
because the risk to benefit ratio should remain favourable. However,
pediatric patients who are just starting out on HIV treatments should not be
offered Viracept until further notice.
Pregnant women who are on Viracept and for whom there is a viable
alternative, should be transferred onto an alternative antiretroviral until
the new manufacturing specifications are implemented and the FDA and Pfizer
say it is safe again.
For pregnant women for whom there is no viable alternative treatment, the
FDA and Pfizer agree that the risk to benefit ratio remains favourable for
them to continue on Viracept. Pregnant women starting out on antiretroviral
treatment should not be offered Viracept however.
The issue of possible contamination arose in June 2007 when another drug
company that also manufactures Viracept, Roche Ltd, detected excess levels
of EMS in the drug. Roche recalled all its Viracept products in the European
Union (EU).
The FDA then asked Pfizer to implement a new specification to limit the
amount of EMS in the Viracept products it makes that are marketed in the US.
When it tested its own Viracept products Pfizer said levels of EMS
"substantially lower than those associated with the Roche EU recall" were
detected.
The drug company said there is no change in the recommended use of Viracept
for other patients and refer professionals to the full prescribing
information that accompanies the letter.
The Pfizer letter asks health professionals, when considering treatment for
patients, to be aware that many HIV antiretrovirals show up as carcinogenic
in animal studies, and some HIV antiretrovirals are mutagenic or
teratogenic. As with all drugs it is a matter of weighing up the benefits
versus the risks, and in the case of HIV-1 antiretrovirals the benefit of
taking them outweight the risk of completely stopping them.
Viracept is an antiretroviral drug for treating patients with HIV in
combination with other medications. In the US it is approved for use in
adults and children over 2 who are infected with HIV-1 (human
immunodeficiency virus, the virus that causes AIDS, acquired immune
deficiency syndrome).
Most adults who are on Viracept take the 625mg tablet while children are
usually prescribed powder or the 250mg tablet.
The active ingredient of Viracept is a a protease inhibitor, nelfinavir
mesylate. It blocks an enzyme that helps to multiply the HIV-1 virus,
preventing the virus from reproducing normally and slowing down the spread
of infection in the body.
Click here to read the full Dear Healthcare Professional letter from the
drug company (PDF).
Click here for FDA drug information page on Viracept.
Written by: Catharine Paddock
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today