The marketing licence for Roche’s HIV drug Viracept has been temporarily suspended by European regulators, a fortnight after it was discovered that batches of the drug had been accidentally contaminated with higher-than-normal levels of a genotoxic substance that can lead to cancer.

The Swiss firm has agreed to the suspension by the European Agency for the Evaluation of Medicinal Products (EMEA) for Viracept (nefinavir), which was recalled at the beginning of June after it was discovered that certain batches of the drug had been contaminated with excess levels of ethyl methansulphonate (EMS), a substance used in the production of the drug.

A meeting of toxicology experts held at the EMEA on June 13 concluded

that there are currently insufficient data to establish which doses of

EMS may be toxic in humans so the agency’s Committee for Medicinal

Products for Human Use (CHMP) has asked Roche to carry out additional studies in animals in order to further understand the potential effects of EMS. Preliminary results should be available by the end of this year.

Also Roche has agreed to establish Viracept patient registries to closely monitor people who may have been exposed to a chemical impurity in their medicine. The CHMP wants the firm to follow patients exposed to high levels of contaminant in the batches of Viracept released since March 2007, as well as all pregnant women and children who have ever taken Viracept, including those exposed in utero.

William Burns, Roche’s head of pharmaceuticals, said that “with the knowledge we have to date, we consider the risk to patients to be low, however we want to be sure patients can be followed and these registries will allow us to do just that ". He added that the “root cause of the elevated levels of impurity observed recently has been identified and we are following up on the agreed actions with EMEA".

Recall causes panic in Zambia

The initial recall did not affect the USA (where Viracept is marketed by Pfizer), Canada or Japan (where it is sold by Japan Tobacco) but the rest of the world was put on alert and this has caused considerable concern. A report by IRIN (part of the UN Office for the Coordination of Humanitarian Affairs), carried by, says the recall “created panic” among HIV-positive Zambians on antiretroviral therapy, who fear other AIDS drugs may not be safe.

Zambia's health minister, Brian Chituwo, announced the immediate discontinuation of the drug, mainly used in second-line treatment, and ordered health workers to explain the incident to affected people. About 1.6 million of the country’s 11.7 million people are infected with HIV, but only 100,000 are currently receiving treatment at state health facilities.

The government estimates that fewer than 1,000 of the people on antiretrovirals - about 1% - are taking Viracept, but independent analysts say the number could be much higher, reports IRIN. According to Nkandu Luo, a former health minister, now an HIV/AIDS consultant, "There could be more people affected by this because some of them take Viracept as part of a combination therapy”. He added that the Government should be speaking to Roche “because the damage has been done. Roche should take responsibility for distributing contaminated drugs."