Drug Interaction Report

Lonafarnib may increase the blood levels of ado-trastuzumab emtansine. This can increase the risk and/or severity of side effects such as liver impairment, heart failure, nerve damage, and bleeding problems. You may not be able to take ado-trastuzumab emtansine during treatment with lonafarnib, or you may need a dose adjustment and/or more frequent monitoring by your doctor to safely use both medications. Your doctor may also be able to prescribe alternatives that do not interact. You should contact your doctor if you experience shortness of breath, coughing, swelling of the legs or ankles, sudden weight gain, palpitations, dizziness or loss of consciousness, as these may be early symptoms of heart failure. You should also seek immediate medical attention if you develop signs and symptoms of liver damage such as fever, chills, joint pain or swelling, unusual bleeding or bruising, skin rash, itching, loss of appetite, fatigue, nausea, vomiting, dark colored urine, light colored stools, and yellowing of the skin or eyes. 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.

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.