Drug Interaction Report

Lapatinib may increase the blood levels of red yeast rice. This can increase the risk of side effects such as liver damage and a rare but serious condition called rhabdomyolysis that involves the breakdown of skeletal muscle tissue. In some cases, rhabdomyolysis can cause kidney damage and even death. You may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. Let your doctor know immediately if you have unexplained muscle pain, tenderness, or weakness while taking these medications, especially if these symptoms are accompanied by fever or dark colored urine. You should also seek immediate medical attention if you develop fever, chills, joint pain or swelling, unusual bleeding or bruising, skin rash, itching, loss of appetite, fatigue, nausea, vomiting, dark colored urine, and/or yellowing of the skin or eyes, as these may be signs and symptoms of liver damage. 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.

Grapefruit juice can significantly increase the blood levels of red yeast rice. This can increase the risk of side effects such as liver damage and a rare but serious condition called rhabdomyolysis that involves the breakdown of skeletal muscle tissue. In some cases, rhabdomyolysis can cause kidney damage and even death. You should avoid the consumption of grapefruit or grapefruit juice during treatment with red yeast rice. Drinking green tea or taking green tea extracts may also increase the blood levels of red yeast rice in some patients. Talk to your doctor or pharmacist if you have any questions or concerns. It may be advisable to avoid excessive consumption of green tea and green tea products while on red yeast rice. Let your doctor know immediately if you have unexplained muscle pain, tenderness, or weakness during treatment, especially if these symptoms are accompanied by fever or dark colored urine. You should also seek immediate medical attention if you develop fever, chills, joint pain or swelling, unusual bleeding or bruising, skin rash, itching, loss of appetite, fatigue, nausea, vomiting, dark colored urine, and/or yellowing of the skin or eyes, as these may be signs and symptoms of liver damage. 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.

Take lapatinib on an empty stomach 1 hour before or 1 hour after a meal unless otherwise directed by your doctor. This will make it easier for your body to absorb the medication. The lapatinib dose is administered once daily and should not be divided. The usual dose of lapatinib is equal to 5 tablets. You may swallow each tablet one at a time, but take the entire lapatinib dose at the same time each day. If you are receiving therapy with lapatinib you should be advised to avoid grapefruits and grapefruit juice. Grapefruit can raise the levels of lapatinib in your body and lead to dangerous side effects.