EMA warns on using Merck hep C drug Victrelis with HIV treatments

Combining Merck & Co's hepatitis C treatment Victrelis with ritonavir-boosted HIV protease inhibitors atazanavir, darunavir and lopinavir may limit the effectiveness of treatment, according to the European Medicines Agency (EMA).

The Agency has recommended that Victrelis' prescribing information be updated to reflect data from a drug interaction study carried out by Merck's European division, Merck Sharp & Dohme (MSD), in healthy volunteers.

Results from this study found that blood levels of all three HIV medicines were significantly lower than expected in patients that had also taken Victrelis, compared to those who were not using the hepatitis C medication.

Blood levels of Victrelis were also lower than expected in patients who used ritonavir-boosted darunavir or lopinavir, although this was not seen with ritonavir-boosted atazanavir.

The EMA's Committee for Medicinal Products for Human Use (CHMP) concluded that these results could mean the drugs are less effective when taken together.

Clinical studies investigating the use of the combination of treatments in patients with both HIV and hepatitis C are ongoing, however, and data from these must be assessed before a clinical impact of the effects of drug interaction can be determined.

The EMA recommends healthcare professionals do not administer Victrelis with ritonavir-boosted darunavir or lopinavir in HIV and hepatitis C co-infected patients, with co- administration of Victrelis with ritonavir-boosted atazanavir only to be considered for certain individuals.

Weight loss drugs like Alli and Xenical okay to use

The EMA also confirmed the safety of two weight loss drugs, GlaxoSmithKline's Alli and Roche's Xenical, which both contain the active ingredient orlistat, in a separate recommendation.

A review of orlistat-containing medicines began August 2011 and was tasked with investigating their relationship with severe liver injuries.

The CHMP's review concluded that the benefits of such treatments outweighed the risks in obese or overweight patients, with the Committee stating there was "no strong evidence that orlistat increased the risk of severe liver injury, and there was no known mechanism by which orlistat was expected to cause liver disorders".

The safety review found that from August 2009 to January 2011, four cases of severe liver injury were reported in patients using Xenical where the role of orlistat could not be excluded.

For Alli users, nine reports of liver failure were recorded between May 2007 and January 2011, although in some cases there were other possible explanations and in other cases there was 'insufficient' information to determine the reason for liver failure.

The EMA did however recommend that the safety information for all orlistat products be harmonised to all give the same details about the possibility of very rare liver-related side effects.