indication

For the treatment of patients with advanced renal cell carcinoma.

pharmacology

Sorafenib is a multikinase inhibitor targeting several serine/threonine and receptor tyrosine kinases. It is commonly available as a tosylate salt. Sorafenib is a multikinase inhibitor that decreases tumor cell proliferation in vitro. Sorafenib inhibits tumor growth of the murine renal cell carcinoma, RENCA, and several other human tumor xenografts in athymic mice. A reduction in tumor angiogenesis occurs in some tumor xenograft models.

mechanism of action

Sorafenib interacts with multiple intracellular (CRAF, BRAF and mutant BRAF) and cell surface kinases (KIT, FLT-3, VEGFR-2, VEGFR-3, and PDGFR-ß). Several of these kinases are thought to be involved in angiogenesis, thus sorafenib reduces blood flow to the tumor. Sorafenib is unique in targeting the Raf/Mek/Erk pathway. By inhibiting these kinases, genetic transcription involving cell proliferation and angiogenesis is inhibited.

toxicity

The highest dose of sorafenib studied clinically is 800 mg twice daily. The adverse reactions observed at this dose were primarily diarrhea and dermatologic events. No information is available on symptoms of acute overdose in animals because of the saturation of absorption in oral acute toxicity studies conducted in animals.

biotransformation

Sorafenib is metabolized primarily in the liver, undergoing oxidative metabolism, mediated by CYP3A4, as well as glucuronidation mediated by UGT1A9. Sorafenib accounts for approximately 70-85% of the circulating analytes in plasma at steady- state. Eight metabolites of sorafenib have been identified, of which five have been detected in plasma. The main circulating metabolite of sorafenib in plasma, the pyridine N-oxide, shows in vitro potency similar to that of sorafenib. This metabolite comprises approximately 9-16% of circulating analytes at steady-state.

absorption

The mean relative bioavailability is 38-49% for the tablet form, when compared to an oral solution. With a high-fat meal, bioavailability is reduced by 29% compared to administration in the fasted state.

half life

25-48 hours

route of elimination

Following oral administration of a 100 mg dose of a solution formulation of sorafenib, 96% of the dose was recovered within 14 days, with 77% of the dose excreted in feces, and 19% of the dose excreted in urine as glucuronidated metabolites.

drug interactions

Carboplatin: Sorafenib may enhance the adverse/toxic effect of carboplatin. Concurrent use of sorafenib with carboplatin and placlitaxel in patients with squamous cell lung cancer is contraindicated. The use of this combination in other settings is not specifically contraindicated, but any such use should be approached with added caution.

Trastuzumab: Trastuzumab may increase the risk of neutropenia and anemia. Monitor closely for signs and symptoms of adverse events.

Tretinoin: The strong CYP2C8 inhibitor, Sorafenib, may decrease the metabolism and clearance of oral Tretinoin. Consider alternate therapy or monitor for changes in Tretinoin effectiveness and adverse/toxic effects if Sorafenib is initiated, discontinued to dose changed.