Ritonavir Norvir

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. 

Clinoleic Clintec/Baxter Norvir Ritonavir Abbott Oral... 

Micelle Formulations A micelle system can be either water-based or oil-based. The use of a micelle formulation for poorly water-soluble drugs for systemic delivery has been well recognized. In recent years, the effective development of self-emulsifying microemulsions or mixed micelle-based lipid formulations products, such as Sandimmun Neoral (cyclosporin), Norvir (ritonavir), and Fortovase (saquinavir), has substantially increased interest in the application of lipid-based micelle formulation to improve oral delivery of poorly water-soluble drugs as well as protein and peptide drugs.51... 

In recent years there has been an increased interest in the utility of lipid-based delivery systems to enhance oral bioavailability (4). It is generally known that membrane permeability is directly correlated to a drug s water-lipid partition coefficient however, the systemic availability of highly lipophilic drugs is impeded by their low aqueous solubility. In an effort to improve this solubility-limited bio-availabiliy,formulators have turned to the use of lipid excipients to solubilize the compounds before oral administration. Several formulations are currently on the market, for example, Sandimmun/Neoral (cyclosporin microemulsion), Norvir (ritonavir), and Fortovase (saquinavir)... 

Figure 1.21 Avandia (rosiglitazone), Glucophage (metformin), Lopinavir, Norvir (ritonavir), Prednisolone, and Dipyridamole.

Norvir (Ritonavir). Abbott Laboratories Ltd. UK Summary of product characteristics. May 2007. 

E N A public statement. Important new pharmacddmtic data demonstmtii that REYATAZ (atazanavir sulfate) combined with NORVIR (ritonavir) and omepmzole should not be co-a inistered. London, 21 December 2004. Available at htQ) //www.emea.eu.int/pdfs/human/fress/pus/20264904eapdf (accessed 21/08/07). 

Bristol-Myers Squibb Company. Re Reyataz (atazanavir sulfate) with or without Norvir (ritonavir) and proton pump inhibitors should not be coadm inister important new pharmacokinetic data, December 2004. Available at htq> //www. fda.gov/oashi/aids/listserv/ 2004/reyataz.pdf (accessed 21/08/07). 

Bertz Shi H, Cavanaugh J, Hsu A. Effect of three vehicles, Advera , Ensure and chocolate milk, on the bioavaUabiltly of an oral liquid formulation of Norvir (Ritonavir). Intersci Corf Antimicrob Agents Chemo r (1996) 36,5. 

Norvir (Ritonavir) Abbott Lab atories Ltd UK Summary of iM-oduct characteristics, Ivfeiy 2007. 

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