Drug Interactions between pemigatinib and suzetrigine

Pemigatinib may be taken with or without food. Do not consume grapefruit, grapefruit juice, or any supplements that contain grapefruit extract during treatment with pemigatinib unless directed otherwise by your doctor. Grapefruit juice can increase the blood levels of pemigatinib. This may increase the frequency and severity of serious side effects such as elevated phosphate levels in the blood (which can eventually lead to low blood calcium levels; calcium deposits in the skin, muscles, and other tissues; anemia; muscle cramps; seizures; and irregular heart rhythm), eye and vision problems, joint pain, mouth sores and inflammation, hair loss, diarrhea, nausea, vomiting, and constipation. 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.

Grapefruit juice can increase the blood levels of suzetrigine. This may increase the frequency and/or severity of side effects such as itching, rash, muscle spasms, and certain laboratory abnormalities including elevated blood levels of creatine phosphokinase (an enzyme found primarily in the heart, brain, and skeletal muscles) and decreased estimated glomerular filtration rate (a measurement of kidney function). You should avoid the consumption of foods or drinks containing grapefruit during treatment with suzetrigine. In addition, taking suzetrigine with food may slow the initial absorption of the medication. To prevent a potential delay in the onset of pain relief, make sure you take the first dose on an empty stomach at least 1 hour before or 2 hours after food, although clear liquids such as water, apple juice, vegetable broth, tea, or black coffee may be consumed during this time. Subsequent doses may be taken with or without food according to the manufacturer. Talk to your doctor or pharmacist if you have questions on how to take this or other medications you are prescribed. 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.

The recommended dosage of pemigatinib should be reduced in patients with severe hepatic dysfunction. No dose adjustment is recommended for patients with mild or moderate hepatic impairment.

Suzetrigine should be avoided in patients with severe liver dysfunction. In patients with moderate liver dysfunction, systemic exposure of this drug and its active metabolite increases, raising the risk of adverse reactions. A lower dose is recommended in these patients. The dosage for patients with mild liver dysfunction is the same as for those with normal liver function.

The recommended dosage of pemigatinib should be reduced in patients with severe renal disease. No dose adjustment is recommended for patients with mild or moderate renal impairment, or those patients with end-stage renal disease receiving intermittent hemodialysis.

Suzetrigine has not been studied in patients with severe renal dysfunction. This drug should be avoided in these patients. The dosage for patients with mild to moderate renal dysfunction is the same as for those with normal renal function.

Pemigatinib can cause retinal pigment epithelial detachment (RPED), which may cause symptoms such as blurred vision, visual floaters, or photopsia. A comprehensive ophthalmological examination including an optical coherence tomography should be performed prior to treatment initiation. Patients with visual disturbances should be closely monitored.