CAPE TOWN, South Africa--(BUSINESS WIRE)--ISENTRESS® (raltegravir) tablets, an integrase inhibitor from Merck & Co., Inc., Whitehouse Station, N.J., U.S.A., was as effective as efavirenz at maintaining viral load suppression to undetectable levels (less than 50 copies/mL) and at improving CD4 counts in previously untreated (treatment-naïve) patients through 144 weeks in a Phase II study still underway. Both medicines were administered in combination with two other anti-HIV medicines, tenofovir and lamivudine. These results were presented today at the 5th International AIDS Society’s (IAS) Conference on HIV Pathogenesis, Treatment & Prevention in Cape Town, South Africa.