The recommended dose of nelfinavir (Viracept) is 1250mg twice a day or 750mg three times daily. These two dosing schedules have similar efficacy^[1][2][3]. In Europe and Australia, nelfinavir is available in 250mg tablets. However, it is available in a 625mg tablet in the United States and Canada, where it is manufactured by Pfizer. This formulation produces similar levels of nelfinavir to the 250mg tablets when taken with food, and allows patients to take fewer tablets every day and is less likely to cause diarrhoea^[4][5][6]. However, it is no longer being developed by Roche, who hold the license for the product in Europe and Australia.

Nelfinavir should be taken with a meal or snack, and a glass of water^[7]. This increases the amount of the drug that gets into the blood. The minimum amount of food advised is a snack like a large sandwich or a baked potato with filling.

The original nelfinavir tablets caused some people to complain of a strange taste in the mouth after taking them with particular liquids, especially fruit juice. Taking the tablets with milk or water seems to reduce the risk of this. However, the currently available tablets are coated, reducing the problems of strange tastes and crumbling of the tablets.

Unlike other protease inhibitors, nelfinavir cannot be boosted with low-dose ritonavir (Norvir).

Patients with moderate to severe liver damage may have altered blood levels of nelfinavir^[8][9]. These patients may benefit from drug level monitoring to ensure that drug levels are appropriate.