Drug Interactions between pralsetinib and voclosporin

Food should not be consumed for at least 2 hours before and at least 1 hour after taking pralsetinib. Do not consume grapefruit, grapefruit juice, any supplements that contain grapefruit, Seville oranges, or Seville orange juice as these products can increase the blood levels of pralsetinib. This may increase the risk and/or severity of serious side effects such as lung problems, liver problems, high blood pressure, fatigue, muscle and joint pain, and bleeding complications. Some sources also warn that combining these medicines could increase the risk of an irregular heart rhythm that may be serious and potentially life-threatening, although it is a relatively rare side effect. You may be more susceptible if you have a heart condition called congenital long QT syndrome, other cardiac disease, conduction abnormalities, or electrolyte disturbance (for example, magnesium or potassium loss due to severe or prolonged diarrhea or vomiting). 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.

Food may delay and reduce the absorption of voclosporin, which may lead to lower blood levels of the medication and possibly reduced effectiveness. Voclosporin should be taken on an empty stomach at least 1 hour before or 2 hours after food. This will make it easier for your body to absorb the medication. Also, while taking voclosporin, you should avoid grapefruits and grapefruit juice. Grapefruit can raise the blood levels of voclosporin in your body and lead to increased adverse effects. Do not increase or decrease the amount of grapefruit products in your diet without first talking to your doctor. Also, if you are taking voclosporin you should avoid potassium-containing salt substitutes or over-the-counter potassium supplements without first talking to your doctor. Taking voclosporin together with these salt substitutes or supplements may cause high levels of potassium in your blood. High levels of potassium can cause weakness, irregular heartbeat, confusion, tingling of the extremities, or feelings of heaviness in the legs. Call your doctor at once if you have any of these symptoms. 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.