Drug Interaction Report

Consumer information for this interaction is not currently available.

MONITOR: Coadministration with potent inhibitors of CYP450 3A4 may increase the plasma concentrations of atrasentan, which is primarily metabolized by CYP450 3A4. When a single dose of atrasentan 10 mg was administered with ketoconazole, a potent CYP450 3A4 inhibitor, atrasentan systemic exposure (AUC) increased by 90%. The risk of adverse effects such as edema, hepatotoxicity and anemia may be increased with this combination. The interaction has not been studied with other, less potent CYP450 3A4 inhibitors.

MANAGEMENT: Caution is advised when atrasentan is used with potent CYP450 3A4 inhibitors. Patients should be monitored for edema, anemia and signs of hepatotoxicity such as nausea, vomiting, abdominal pain, dark urine, loss of appetite, itching and/or yellowing of the skin or eyes.

Lonafarnib should be taken with the morning and evening meals and an adequate amount of water. Do not consume grapefruit, grapefruit juice, or Seville oranges (also known as bitter or sour oranges).During treatment with lonafarnib. Juice from grapefruits and Seville oranges can increase the blood levels of lonafarnib. This may increase the risk and/or severity of side effects such as nausea, vomiting, diarrhea, loss of appetite, electrolyte (e.G., calcium, magnesium, potassium, phosphate, sodium) abnormalities, liver problems, low red and white blood cell counts, infection, and high blood pressure. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.