Conditions: Healthy
Keywords: Antiretrovirals Protease Inhibitors Herbal Supplements Drug Interactions Metabolism Healthy Volunteer HV
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 47
Healthy volunteers: yes

Brief summary:
This study will examine the interaction of the HIV combination medication lopinavir/ritonavir with the herbal products echinacea, ginseng, and ginkgo biloba. Patients with HIV infection often take herbal products and dietary supplements in addition to their doctor-prescribed medicines to treat the disease, lessen the side effects of anti-viral drugs, and improve their overall well being. Alternative medicines such as these may, however, interfere with the elimination of lopinavir/ritonavir from the body, causing either higher or lower blood levels of these drugs than would be expected. This study will assess in healthy subjects any potential harms of taking echinacea, ginseng, or ginkgo biloba together with lopinavir/ritonavir.

Healthy normal volunteers between 18 and 50 years of age may be eligible for this study. Candidates are screened with a history, physical examination, and blood tests, including an HIV test and a pregnancy test for women. Pregnant women are excluded from the study. Participants come to the NIH Clinical Center after fasting overnight for the following procedures:

Visits 1 and 2: A catheter (plastic tube) is placed in an arm vein to collect blood samples. After the first sample is drawn, the subject takes 8 mg of midazolam syrup and two fexofenadine tablets. Midazolam is a sedative, and fexofenadine (Allegra) is a medicine used to treat allergies. Subjects are given breakfast an hour after taking the drugs. Blood samples are collected at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8 and 24 hours after taking the drugs to measure blood levels of fexofenadine. An extra sample is collected at the 4-hour mark to measure the midazolam level. The catheter is removed after the 8-hour blood draw and subjects are dismissed home. They return the following morning (visit 2) for the 24-hour blood draw.

Visit 3: From 7 to 28 days after visit 1, subjects begin taking lopinavir/ritonavir capsules twice a day by mouth for a total of 29.5 days. On day 15 they return to the clinic for lopinavir/ritonavir blood levels as were done for fexofenadine, except that samples are collected once before breakfast and then at 0.5, 1, 2, 3, 4, 6, 8 and 12 hours after the lopinavir/ritonavir dose. An extra sample is collected for routine tests. The catheter is removed after the 12-hour draw and the subject is dismissed home.

The next morning, subjects begin taking one of the following: echinacea 500 mg 3 times a day; ginkgo biloba 120 mg twice a day; or ginseng 500 mg 3 times a day for 28 days.

Visit 4: On the last day of taking lopinavir/ritonavir, subjects return to the clinic again for blood level measurements of these drugs as on visit 3, except that the catheter is removed and the subject dismissed home after the 8-hour blood draw.

Visits 5 and 6: On the last day of taking the herbal supplement, subjects return to the clinic for repeat measurement of fexofenadine and midazolam levels, as described in visits 1 and 2. At the final visit (visit 6) an additional blood sample is collected for repeat laboratory testing.

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Detailed description:
Patients with HIV commonly use herbal products and dietary supplements in addition to medications prescribed by their physicians. Up to 73% of patients with HIV have reported using some form of complementary or alternative medicine. As such, the potential for clinically significant drug interactions between herbs and antiretrovirals is becoming increasingly appreciated. Despite this awareness, little is known about the effect of commonly used herbal products, such as echinacea, ginkgo biloba, and ginseng, on antiretroviral pharmacokinetics. Interacting herbal supplements have the potential to alter protease inhibitor (PI) plasma concentrations, as has been shown with St. John's Wort and garlic. Drug interactions may potentially increase antiretroviral concentrations, putting patients at risk for toxicities, or lower drug concentrations below the threshold of viral susceptibility, putting patients in jeopardy of antiretroviral failure. The protease inhibitors lopinavir and ritonavir both rely principally on cytochrome P450 (CYP) 3A4 metabolism for their elimination. In addition, both drugs are substrates for the transport protein p-glycoprotein (P-gp), which may also contribute to their distribution and elimination.

The primary purpose of this investigation is to determine whether the herbal supplements Echinacea purpurea, ginkgo biloba, and Panax ginseng alter the pharmacokinetic properties of the HIV protease inhibitor (PI) lopinavir, administered as the PI combination lopinavir/ritonavir (LPV/r). This is an open label pharmacokinetic study that will be performed on an outpatient basis. A total of 42 study participants who have met inclusion criteria will be sequentially divided into one of 3 groups, such that 14 subjects each will receive LPV/r alone and in combination with either E. purpurea, G. biloba, or P. ginseng.

Subjects will begin taking LPV/r (400mg/100mg twice daily x 29.5 days), returning to the NIH on Day 15 of dosing for post-dose plasma collection and determination of lopinavir and ritonavir concentrations. On Day 16 participants will begin taking either E. purpurea (500mg, three times daily), G. biloba extract (120 mg, twice daily), or P. ginseng (500 mg, twice daily) for 28 days. On the 30th day of LPV/r (Day 15 of the herb), subjects will return to the NIH where they will take their final LPV/r dose and then have their plasma collected for determination of lopinavir concentrations. Data from this investigation will determine whether echinacea, ginseng, or ginkgo biloba supplements alter the pharmacokinetics of lopinavir.

Arms:
arm 1: The primary outcome measurement for each study arm is the change in lopinavir area under the concentration versus time curve (AUC) after two weeks administration of an herbal preparation (Ginkgo Biloba). arm 2: The primary outcome measurement for each study arm is the change in lopinavir area under the concentration versus time curve (AUC) after two weeks administration of an herbal preparation (Echinacea purpurea). arm 3: The primary outcome measurement for each study arm is the change in lopinavir area under the concentration versus time curve (AUC) after two weeks administration of an herbal preparation (Panax ginseng).

Interventions: intervention 1: Gingko Biloba intervention 2: Echinacea purpurea intervention 3: Panax ginseng
Intervention descriptions: intervention 1: Ginkgo Biloba 120 mg twice daily for 14 days intervention 2: Echinacea purpurea 500 mg three times daily for 14 days intervention 3: Panax ginseng 500 mg twice daily

Protocol document: