New 625mg formulations of nelfinavir

The US Food and Drug Administration has approved a new dosing formulation of the protease inhibitor Viracept (nelfinavir mesylate). Viracept has been available in 50 mg oral powder and 250 mg tablets. The new formulation of 625 mg reduces the pill burden from five-250 mg tablets twice a day to two-625 mg tablets twice a day, potentially facilitating adherence to treatment regimens.

Results of the bioequivalence study of the 250-mg tablet and the 625-mg tablet revealed increased bioavailability with the 625-mg formulation.

The sponsor, Agouron Pharmaceuticals, submitted clinical safety and pharmacokinetic data to the FDA providing evidence that the higher exposures do not pose a safety risk. However, diarrhoea may be more common in patients receiving this 625 mg formulation. No efficacy information was contained in this submission because it is unlikely that a more bioavailable formulation would be less efficacious.

Roche have developed a separate 625mg formulation of nelfinavir to be marketed in Europe, that will shortly be submitted to the European agency.

Comment

Almost simultaneously Agouron and Roche have both produced separate, new, reduced pill formulations for nelfinavir. These both contain the same amount of nelfinavir but the formulations are not the same and the excipients used are entirely different. The Agouron formulation will only be available in the US. Results from clinical studies of the Roche formulation that will marketed in the rest of the world, showed a reduction in diarrhoea and were presented at the 4th Workshop on Clinical Pharmacology, and reported in last month’s HTB.

An expanded access programme in the UK for the reduced tablet, but larger pill, for people with either intolerance or adherence difficulties, will be in early June 2003. European application for approval has not yet been submitted but Roche are hoping for licensing in early 2004.