The standard dose of d4T (stavudine, Zerit) is one 40mg capsule twice a day. However, patients weighing less than 60kg usually take 30mg twice daily. d4T is also available as a powder, which is dissolved in water before being taken.

d4T can be taken before or after food. Although the package information suggests that d4T should always be taken on an empty stomach for faster absorption, studies have shown that food does not make any difference to the total amount of d4T absorbed.

In people with impaired kidney function or peripheral neuropathy, the dose of d4T may be reduced to 15 or 20mg twice daily.

As d4T capsules contain lactose, patients with lactose intolerance should not take them.

It is important to take d4T as prescribed in order to maintain the right level of the drug in the blood. If blood levels of the drug fall too low, this may allow the development of resistance to d4T and affect future treatment options.

A once-daily extended-release formulation of d4T known as Zerit PRC in Europe and Zerit XR in the United States has been developed. This formulation of d4T has similar efficacy to the immediate release version and received approval in late 2002^[1]. However, production problems delayed the launch of the new formulation, leading to the manufacturer withdrawing its marketing authorisation in February 2005.