A new anti-CMV agent manufactered by Bristol Myers Squibb, Inc. was presented at the 4th National Conference on Retroviruses and Opportunistic Infections. Lobucavir is a cyclobutyl analog of guanine with broad spectrum antiviral activity against most herpes viruses and Hepatitis B. Lalezari and colleagues from Mount Zion Medical Center in San Francisco presented a study examining the pharmacokinetics, safety and activity of lobucavir in HIV infected patients. Doses studied were 200 mg twice daily, 200 mg four times daily and 400 mg four times daily. The pharmacokinetic indicated that there was greater drug exposure with increasing doses. Antiviral activity was measured by eradication of CMV from urine and reduction of CMV titers in semen. All doses were well tolerated without drug related clinical or laboratory related side effects including absence of myelosuppression. At the two highest doses there was a 50% reduction in CMV viruria and a greater than 1 log reduction in HIV viral load from semen at the highest dose. The drug was well tolerated with few side effects, and further studies are planned, since it is one of the few oral agents with activity against CMV which may have a role in the treatment and prevention of this disease as strains of CMV become resistant to the available agents, ganciclovir, foscarnet and cidofivir.