Pazopanib, sold under the brand name Votrient, is a medication used to treat renal cell carcinoma (RCC) and certain soft tissue sarcoma.[2] In RCC it is used when other treatments have failed.[2] It is taken by mouth.[2]
Pazopanib was approved for medical use in the United States in 2009.[1] In Europe it received conditional approval in 2010 and full approval in 2013.[5] In the United Kingdom it costs the NHS about £2,250 per month as of 2021.[2] In the United States this amount costs about 14,200 USD.[6]
Haematologic parameter alterations have been reported in 31–37% of patients.
Events of cardiac dysfunction (decreased left ventricular ejection fraction and congestive heart failure) have been observed.
Fatal haemorrhage, arterial and venous thrombotic events and perforations in the gastrointestinal tract have been observed in randomized clinical trials.
It has one black box warning by the US FDA, namely severe hepatotoxicity including fatalities.[4][7]
The most common side effects of pazopanib are nausea, vomiting, diarrhoea (occurs in about half of patients), changes in hair colour, hypertension (which usually occurs during the first few weeks of treatment), appetite loss, hyperglycaemia, hypoglycaemia, electrolyte abnormalities (including hypocalcaemia, hypomagnesemia, hypophosphatemia), laboratory anomalies (including increased AST, ALT and protein in the urine), oedema, hair loss or discolouration, taste changes, abdominal pain, rash, fatigue and bone marrow suppression (including leucopenia, neutropenia, thrombocytopenia and lymphopenia).[13] It has been associated with a low, but real risk of potentially fatal liver damage.[13]
Co-administration with strong inhibitors of the liver enzyme CYP3A4 (e.g. ketoconazole, ritonavir, clarithromycin, grapefruit juice) may increase pazopanib serum levels as it is a CYP3A4 substrate.
Pazopanib is a multiple kinase inhibitor that limits tumor growth by targeting angiogenesis via inhibition of enzymes including vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), c-KIT and FGFR.[4][13][17][18][19][20]
After oral intake of a single tablet, pazopanib has a bioavailability of 21% with a range of 14–39% between people. It reaches highest concentrations in the blood plasma after median 3.5 hours; the range in studies was 1.0 to 11.9 hours. When taken regularly, the area under the curve (AUC) increases 1.23- to 4-fold as compared to a single dose. Taking the drug together with food approximately doubles the AUC as well as the highest plasma concentrations (Cmax); and crushing the tablet increases the AUC 1.46-fold, as well doubling the Cmax.[3][8]
When in the bloodstream, more than 99.5% of the substance are bound to plasma proteins. The liver enzyme mainly responsible for metabolizing the drug is CYP3A4; and there are minor contributions from CYP1A2 and CYP2C8. Metabolites identified in tests with human liver cells and microsomes include various hydroxyl derivatives and possibly a carboxylic acid. Only 6% of the circulating substance is in the form of metabolites, and all but one of them are 10- to 20-fold less active than pazopanib itself. Consequently, the metabolites are not considered important for the drug's therapeutic effect.[3][8]
Pazopanib is eliminated with a biological half-life of 30.9±4 hours on average (range 21–51 hours) mainly via the faeces. Less than 4% are eliminated via the urine.[3][8]
↑ 13.013.113.2Zivi, A; Cerbone, L; Recine, F; Sternberg, CN (September 2012). "Safety and tolerability of pazopanib in the treatment of renal cell carcinoma". Expert Opinion on Drug Safety. 11 (5): 851–859. doi:10.1517/14740338.2012.712108. PMID22861374. S2CID2178331.
↑Schöffski, P (June 2012). "Pazopanib in the treatment of soft tissue sarcoma". Expert Review of Anticancer Therapy. 12 (6): 711–723. doi:10.1586/era.12.41. PMID22716487. S2CID1738165.
↑Pick, AM; Nystrom, KK (March 2012). "Pazopanib for the treatment of metastatic renal cell carcinoma". Clinical Therapeutics. 34 (3): 511–520. doi:10.1016/j.clinthera.2012.01.014. PMID22341567.