9. A history of severe drug allergy or hypersensitivity. 10. The use of any of the following potent cytochrome P450 inhibitors in the 14 days preceding randomization (e.g. ketoconazole, itraconazole, fluconazole, erythromycin, troleandomycin clarithromycin, indinavir, nelfinavir, ritonavir and saquinavir).