Merck & Co sees positive data from MK-0518

US drug giant Merck & Co says that its investigational oral HIV integrase inhibitor MK 0518 has, so far, provided a greater suppression of viral load in ongoing trials, than placebo. The Phase II study, which is being run as a multicenter, randomized, double-blind, placebo-controlled dose-ranging assessment of the drug's effect on viral load and CD4 cell count, is also designed to establish the compound's safety and efficacy. Initial findings were presented at the 13th Annual Conference on Retroviruses and Opportunistic Infections, held in Denver, Colorado, USA.

Interim results suggest that all three doses of the drug (200mg, 400mg and 600mg), in combination with optimized background therapy, had greater antiviral activity than placebo and OBT. In addition, 56%-72% of patients taking the drug had achieved a viral load of less than 50 copies/ml after 16 weeks of treatment, versus just 19% who reached this level while taking placebo.

Bach-Yen Nguyen, senior director of infectious diseases and clinical research at Merck, commented: "the efficacy of MK-0518 provides additional evidence that demonstrates the antiviral activity of HIV integrase inhibitors as a new and promising class of antiretroviral agents." The firm says that it is initiating two Phase III studies that will further examine the drug's efficacy and tolerability in treatment-experienced patients who may have developed resistance to other anti-retrovirals.