Drug Interaction Report

Talk to your doctor before using macitentan together with ritonavir. Combining these medications can significantly increase the blood levels of macitentan. This may increase the risk of side effects such as headache, anemia and liver problems, especially during prolonged treatment. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. Call your doctor immediately if you have fever, chills, joint pain or swelling, unusual bleeding or bruising, skin rash, itching, loss of appetite, fatigue, nausea, vomiting, abdominal pain, dark colored urine, light colored stools, 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.

Ritonavir should be taken with food to lessen gastrointestinal side effects. It is important that you take this medication exactly as prescribed by your doctor. Do not change your treatment or stop treatment without first talking to your doctor.

Food significantly increases the absorption of paritaprevir. You should take each dose of paritaprevir with a meal. Taking it on an empty stomach may lead to inadequate blood levels and reduced effectiveness of the medication.