European regulators are following the example of their counterparts in the USA and are planning to investigate the safety of medicines containing GlaxoSmithKline’s HIV drug abacavir.

The move by the European Medicines Agency has been prompted by data from the D:A:D (Data collection of Adverse effects of anti-HIV Drugs’) study, which has just been published in The Lancet and suggests an increased risk of heart attack associated with the use of abacavir-containing medicines. Abacavir is marketed by GSK as Ziagen and the drug is also used in combination with lamivudine (and sold as Kivexa) and with lamivudine and zidovudine (marketed as Trizivir).

The EMEA did note that "at present no changes to the prescribing information for abacavir-containing medicines are required, but further information is needed to determine the risk of myocardial infarction with abacavir-containing medicines". The US Food and Drug Administration announced that it was also conducting a similar review last week.

The D:A:D study, which now includes more than 33,000 patients, was initiated in 1999 with the aim of assessing associations between the use of anti-HIV medicines and the risk of cardiovascular disease. The results suggested that use of abacavir within the previous six months is associated with an increased risk of myocardial infarction, but no significant risk was noted six months or more after they had stopped taking the drug. A similar but weaker association was seen with Bristol-Myers Squibb’s Videx (didanosine).

However GSK disputes the D:A:D data and notes that in a pooled analysis of 54 clinical trials sponsored by the firm no increased risk of myocardial infarction with the use of abacavir was observed. These studies included a total of more than 9,600 patients.

Didier Lapierre, vice president of clinical development for infectious diseases at GSK, said it is important to note that although the relative risk of heart attack risk seen in the D:A:D study was increased in patients who had recently taken abacavir, “the likelihood of an individual patient having a heart attack remains low in absolute terms”. He added that abacavir is “an important treatment option for patients with HIV and patients should not discontinue treatment on their own".