Istradefylline 40 mg/day greater peak levels and AUC of CYP3A4 substrates in scientific trials. This effect was not noticed with istradefylline 20 mg/day. Look at dose reduction of delicate CYP3A4 substrates.If you are allergic to this drug; any aspect of the drug; or another medications, foods, or substances. Explain to your doctor with regard to