Pharmacokinetic Interactions With Prednisolone in Healthy Volunteers and HIV-infected Patients Receiving Single-Dose Prednisone

Study Summary

This study will evaluate the impact of the HIV protease inhibitor ritonavir on the pharmacokinetics-that is, the interaction of the medication and the body-of prednisolone after prednisone is given to healthy volunteers. Prednisone, an agent known as a corticosteroid, or steroid hormone, is converted by the body into prednisolone. Ritonavir is an HIV medication that fights the virus by blocking its ability to reproduce. Sometimes it increases the blood levels of other drugs given at the same time, and it is possible that ritonavir increases the blood levels of prednisolone and those of other medications. Results from the study will provide information on whether prednisone and ritonavir interact in a potentially harmful way. The MDR1 genotype, that is, part of a person's genetic constitution, may influence how prednisolone behaves. Patients 18 to 50 years of age who are in good health, who not have HIV, and who do not smoke may be eligible for this study. There will be 10 participants and another 5 later who will be control subjects. Those in the control group will take only prednisone, not ritonavir. Participants will undergo the following tests and procedures: * Medical history and physical examination. * Collection of blood and urine to assess general health. * Collection of blood to examine markers on white blood cells and to determine the kind of MDR1 gene was inherited. * HIV test. The screening visit will take about 3 to 4 hours, and the study will take about 28 to 49 days. For 3 study days, participants will remain in the clinic for 12 hours, On Study Day 1, patients will be asked to not eat or drink anything besides water before coming to the clinic. Blood samples will be collected to measure prednisolone concentration as well as osteocalcin, a blood protein involved in bone formation. Blood tests will also allow a look at the surfaces of some white blood cells. Patients will receive a breakfast along with 20 mg of prednisone. Urine samples will be coll