NOURIANZ

Istradefylline 20mg, Oral tablet

Grapefruit juice

· Severity: Major

· Notes for Consumers: Do not take Grapefruit juice or grapefruit-containing foods together with Istradefylline without talking with your health care provider. Side effects of Istradefylline may get worse. Report any new or worsening side effects such as uncontrolled or sudden movements, abnormal thinking or behavior, hallucinations, dizziness, constipation, nausea, or trouble sleeping to your doctor or healthcare professional.

· Notes for Professionals: It may be advisable for patients to avoid grapefruit juice or grapefruit-containing foods while taking istradefylline as istradefylline exposure and adverse effects may increase. Grapefruit juice is a strong CYP3A4 inhibitor. Istradefylline exposure was increased by 2.5-fold when administered with a strong inhibitor in a drug interaction study.

Istradefylline 20mg, Oral tablet

Tobacco

· Severity: Major

· Notes for Consumers: Tobacco smoke contains substances that may speed the removal of Istradefylline from the body; if you start smoking, the Istradefylline may become less effective. Just the opposite occurs when someone stops smoking tobacco; if you stop smoking this may increase the amount of Istradefylline in the blood. Side effects of your therapy may get worse. Inform your prescriber if you are a smoker or if you are going to stop smoking; your prescriber will closely monitor you to see if a change in dose is needed.

· Notes for Professionals: The initial and maximal recommended istradefylline dosage in patients who smoke 20 or more cigarettes per day (or the equivalent amount of another tobacco product) is 40 mg once daily. Tobacco smoking produces polycyclic aromatic hydrocarbons that induce hepatic microsomal enzymes, particularly CYP1A enzymes, and this induction increases the systemic clearance of istradefylline. Those who use or smoke tobacco at the equivalent of 20 cigarettes per day or more have significantly decreased steady-state systemic exposure to istradefylline. If a patient stops smoking, the prescriber should adjust the dosage downward as clinically indicated.

<b>DISCLAIMER:</b><em> This drug information content is provided for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Patients should always consult their physician with any questions regarding a medical condition and to obtain medical advice and treatment. Drug information is sourced from GSDD (Gold Standard Drug Database ) provided by Elsevier.</em>