Drug Interaction Report

Pacritinib may increase the blood levels and effects of methylnaltrexone. This may increase the risk and/or severity of side effects of methylnaltrexone. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring to safely use both medications. Contact your doctor if your condition changes or you experience increased side effects. 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 may increase the blood levels of pacritinib. This can increase the risk of side effects such as diarrhea, low blood platelet count, infection, and an irregular heart rhythm that may be serious or life-threatening. You should avoid consuming grapefruit and grapefruit juice during treatment with pacritinib. However, if you have been regularly consuming grapefruit or grapefruit juice with the medication, then it is advisable for you to talk with your doctor before changing the amounts of these products in your diet, as this may alter the effects of your medication. Contact your doctor if you have any questions or concerns or if you develop dizziness, lightheadedness, fainting, shortness of breath, chest pain, or heart palpitations during treatment. 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.

Food may reduce the absorption of methylnaltrexone when taken orally, which may lead to lower blood levels of the medication and possibly reduced effectiveness. You should take oral preparations of methylnaltrexone on an empty stomach at least 30 minutes before your first meal of the day.