Approved Drugs: Pazopanib (Votrient) Indications
Treatment of patients with advanced renal cell cancer.
Mechanism of Action
Prevents angiogenesis (new blood vessels), and growth of some tumors. It is a multitargeted tyrosine kinase inhibitor of:
•Vascular endothelial growth factor receptor 1,2,3 (VEGFR-1,2,3)
• Platelet derived growth factor receptor (PDGFR)-α and β
• Fibroblast growth factor receptor (FGF)-1,3
• Cytokine receptor (Kit)
• Interleukin-2 (IL-2) receptor inducible T-cell kinase (Itk)
• Leucocyte-specific protein tyrosine kinase (Lck)
Following oral dosing, drug reaches peak plasma concentration in 2–4 hours. If tablet is crushed rather than swallowed whole, bioavailability and area under the curve (AUC) serum level are increased by 46%. Administration with high-fat meal also increases AUC, so a whole tablet should be taken on an empty stomach. Drug is primarily metabolized by CYP3A4 hepatic enzyme system, and to a minor degree by CYP1A2 and CYP2C8. Drug mean half-life is 30.9 hours after administration. Drug is eliminated in the feces, and to a lesser degree in the urine. If patient has moderate hepatic impairment, drug clearance is reduced by 50%, so drug dose should be reduced in these patients.
Drug Administration
• Pazopanib 800 mg orally once daily without food (at least 1 hour before or 2 hours after a meal).
• Drug dose in moderate hepatic impairment is 200 mg orally without food.
• Drug is not recommended for patients with severe hepatic impairment, defined as total bilirubin > 3 × upper limit of normal (ULN) with any level of alanine transaminase (ALT).
• Coadministration of strong CYP3A4 inhibitor (eg, ketoconazole(Drug information on ketoconazole), ritonavir, clarithromycin(Drug information on clarithromycin)): Reduce dose of pazopanib to 400 mg orally once daily without food, but may need further dose reduction if side effects are severe.
• Patients who require concomitant chronic administration of strong CYP3A4 inducer medication should not take pazopanib.
• Available as 200- and 400-mg tablets.
Patient Education
• Drug may cause changes in liver and bile blood chemistry results so patient’s blood will be monitored closely (liver function tests) before starting therapy, and at least every 4 weeks for the first 4 months of therapy, or more frequently if needed.
• Drug may cause loss of pigment in the hair strands (depigmentation) during treatment, which will return to normal once the drug is stopped.
• It is very important to take the medicine on an empty stomach; if taken with food, this may increase the drug side effects.
• Rarely, severe and possibly fatal liver damage may occur. Patient should call doctor right away if s/he experiences any of the following: yellowing of the skin or whites of the eyes; unusual darkening of the urine; unusual tiredness; pain in the right upper part of abdomen.
• Women of child-bearing potential should use effective birth control measures to prevent pregnancy, as the drug may harm the fetus. Mothers should not nurse while receiving the drug.
Drug Interactions
• CYP3A4 inhibitors (strong, eg, ketoconazole, ritonavir(Drug information on ritonavir), clarithromycin, grapefruit or juice): may increase the plasma pazopanib concentration. Avoid coadministration. (For more information, see ONCOLOGY Nurse Edition 22(11):33,52–56, February 2009.) If coadministration is necessary, consider a dose reduction of pazopanib.
• CYP3A4 inducers (strong, eg, rifampin): may decrease the plasma concentration of pazopanib. Avoid coadministration.
