Mrs. Stephens, we’re going to do some bloodwork to check, but all of the grapefruit juice you’re drinking is probably inhibiting your cytochrome P450 liver enzymes, especially CYP3A. As a result, the Lipitor you’re taking is building up in your bloodstream instead of being processed correctly. We’ll get the bloodwork done, and you should be on your way soon. You’ll be fine, just stay off the grapefruit juice,” Dr. McPherson says. She leaves to attend to her next patient. Mrs. Stephens looks confused. “I really don’t understand what the doctor just said. Grapefruit juice is so healthy! How can it be bad for me?” You need to make sure you have your facts straight to help explain the situation to Mrs. Stephens and her daughter. Answer these questions to make sure you can have a good conversation with your patient. Questions 1. What is the grapefruit diet, and is there research data to support its effectiveness? 2. What is an enzyme? 3. What kinds of reactions do cytochrome P450 enzymes like CYP3A carry out? 4. Based on how P450 enzymes modify their substrates, how does this affect the water solubility and excretion (in the urine) of the substrates? 5. How are P450 drugs involved in the normal pharmacokinetics of drugs like Lipitor? 6. What kinds of drug side effects can be seen if a patient’s P450 enzymes are not functioning at a normal level, through their own unique biochemistry or through other drug or substance interactions?