Norvir

Norvir 600 mg/7.5 mL (when ritonavir mild hepatic impairment to improve paresthesias hyperlipidemia 2D6 potent... 

Ritonavir is a product of Abbott Laboratories Ltd. for the treatment of HIV and is marketed as Norvir , in liquid and semisolid capsule formulations. It received FDA approval for market launch in march 1996, at which time only one polymorphic form of Ritonavir (Form I) was known. Two years later in early 1998 a laboratory responsible for testing the formulated product in the US reported dissolution test failures of the semisolid capsules, and noted that drug product had precipitated out of solution. A new polymorphic form had been discovered that was thermodynamically more stable than the existing form and approximately 5 times less soluble in the formulation. Figure 7. 

Nelfinavir (Viracept) Nevirapine (Viramune) Raltegravir (Isentress) Ritonavir (Norvir) Saquinavir (Fortovase, Invirase)... 

Although ritonavir (Norvir) is a potent inhibitor of HIV-1 and HIV-2 protease, it is not well tolerated in higher doses. It is mainly used in low doses to increase blood levels of other protease inhibitors and to extend their dosing interval. Ritonavir is more commonly associated with gastrointestinal side effects, altered taste... 

HIV-1 infection PO knlirelroviral-naive. 400 mg (2 capsules) once a day with food. A -tiretroviral-experienced. 300 mg and ritonavir (Norvir) 100 mg once a day. 

Norvir soft gelatin capsules are available for oral administration in a strength of 100 mg ritonavir with the following inactive ingredients butylated hydroxytoluene, etha-... 

Norvir oral solution is available for oral administration as 80 mg/mL ritonavir in a peppermint- and caramel-flavored vehicle. Each 8-ounce bottle contains 19.2 g ritonavir. Norvir oral solution also contains ethanol, water, polyoxyl... 

Norvir (ritonavir, ABT-538) by Abbott (Kalamazoo/MI, USA) in phase II demonstrated a 100-fold reduction of viral count, more than Crixivan and AZT. The threefold enhancement of CD4-T cell count after 12 weeks is also an improvement over AZT. However, even ABT-538 develops resistances, albeit more slowly than Crixivan. Hepatic side effects limit doses to 600 mg twice daily. Ritonavir has high oral bioavailability, about 78% in rats, good solubility (5.3 g IT1 (pH 7.4) to 6.9 g L-1 (pH 4.0)), and a plasma half-life of 1.2 h (Kempf, 1995). The molecule is difficult to produce in phase II, the overall yield in production was 2% ( ) in addition, the product was cherry-red. The combination of ritonavir and saquinavir has also been reported to dramatically increase saquinavir plasma concentrations (by as much as 50-fold). Ritonavir is believed to act by inhibiting cytochrome P450 (CYP 3A4), the enzyme responsible for saquinavir first-pass metabolism. 

The ability of lipid vehicles (either in the pharmaceutical formulation or in food) to enhance the absorption of lipophilic drugs has been well known for many years. Recently, successful bioavailability enhancement utilizing lipid-based formulations has been accomplished with the immunosuppressive agent cyclosporine A (Neoral, Novartis Pharmaceuticals Corporation, East Hanover, NJ), and for the two HIV protease inhibitors ritonavir (Norvir, Abbott Laboratories, IL) and saquinavir (Fortovase, Roche Pharmaceuticals, Nutley, NJ). Consequently, considerable interest in lipid-based formulations has been aroused. 

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