Today the Food and Drug Administration approved a new, extended release formulation of Zerit (stavudine, d4T) called Zerit XR. This extended-release formulation has been demonstrated to maintain measurable plasma concentrations for 24 hours after once-daily dosing. Zerit XR is indicated for the treatment of HIV in combination with other antiretrovirals. The recommended dose of Zerit XR is 100 mg once daily for individuals weighing at least 60 kg and 75 mg once daily for individuals weighing less than 60 kg.

In a clinical study conducted in 783 treatment-na•ve, HIV-infected individuals Zerit® XR was comparable to the previously approved twice daily formulation of Zerit. In this randomized, controlled study, participants were randomized to either the extended release or standard formulation, in combination with lamivudine and efavirenz. The proportion of patients with HIV-RNA (viral load levels) below 400 copies/mL at 48 weeks was 79% and 76% for the extended release and immediate release-containing regimens, respectively. For viral load under 50, the response rates were 55% and 57% for the new and old formulations, respectively. The tolerability and safety profile of the new once daily, extended release formulation is comparable to that of the previously approved twice daily formulation.

The study results were supported by a second, smaller study in 150 treatment na•ve patients.

More convenient formulations, such as Zerit XR, may help patients with HIV more readily adhere to treatment regimens.

The full label will soon be available at the FDA Web site. Simply click "Z" in the index, and scroll to look for Zerit XR.

Zerit XR is a product of the Bristol-Myers Squibb Company.