This study will examine how the anti-HIV protease inhibitor lopinavir/ritonavir (Kaletra®
(Registered Trademark)) affects the function of the endothelium (lining of the arteries).
Medications such as protease inhibitors can dramatically change the course of HIV infection
in many patients; however, among their side effects is development of abnormal lipid levels
resulting in high cholesterol and insulin resistance. These side effects may damage the
lining of the arteries that supply blood to the heart, leading to premature coronary artery
disease. The study will determine whether lopinavir/ritonavir directly affects endothelial
function and whether it alters cholesterol levels, glucose tolerance, and markers of
inflammation in people who take the drug for 4 weeks.
Healthy normal volunteers between 18 and 40 years of age may be eligible for this study.
Candidates must be HIV-negative and have no history of heart disease, hypertension, or
diabetes mellitus. They must not have smoked for at least 6 weeks before entering the
study. Volunteers will be screened with a medical history, physical examination, blood
tests (including a pregnancy test for women of childbearing potential), and
electrocardiogram. In addition, candidates will have an oral glucose tolerance test (see
Participants will undergo the following procedures:
- Lopinavir/ritonavir: 4 weeks (3 capsules twice a day) beginning study day 1
- Flow-mediated vasodilatation test (study days 0 and 29) - An ultrasound device for
measuring the size of the brachial artery (artery in the upper arm) is placed just
above the elbow. The size of the artery is measured before and 5 minutes after blood
flow to the arm is stopped for 5 minutes, using a blood pressure cuff. The artery is
also measured before and after taking nitroglycerin, a medicine that dilates blood
vessels. These measurements tell how well the drug treatment works on the cells lining
the brachial artery, which is an indicator of coronary artery function. This test takes
about 1.5 hours.
- Forearm blood-flow test (study days 1 and 30): Small tubes are inserted into an artery
and vein in the forearm at the inside of the elbow. Blood pressure cuffs are placed
around the upper arm and wrist, and a strain gauge (a rubber band-like device) is
placed around the forearm. When the blood pressure cuffs are inflated, blood flows into
the forearm, stretching the strain gauge at a rate proportional to the blood flow. When
the devices are in place, a salt water solution is injected in the small tube in the
artery. After 20 minutes, small doses of the following drugs are given through the
catheter at various intervals: 1) L-NMMA (blocks production of nitric oxide, a
substance produced by the blood vessels that causes them to dilate); 2) sodium
nitroprusside (dilates blood vessels, increasing blood flow); 3) acetylcholine (lowers
blood pressure); and 4) acetylcholine plus L-NMMA. The effect of the different drugs on
blood flow in the forearm is measured. The study takes about 2 hours to complete.
- Blood tests (screening and study days 1,15, 30, and 44)
- Electrocardiogram (at screening and on study day 30)
- Oral glucose tolerance test (at screening and on study day 30) - A blood sample is
collected. Then, the subject drinks 300 milliliters of a glucose solution (a liquid
that contains sugar dissolved in water). Two hours after drinking the solution, blood
is drawn again to examine how the body responds to the increase blood sugar levels.
With the advent of the highly active antiretroviral (ARV) therapy era, patients with human
immunodeficiency virus (HIV) have had significantly decreased mortality and morbidity.
Concomitant with more patients chronically taking antiretroviral therapy, there has been an
increase in atherogenic lipoprotein profiles (high cholesterol, high triglycerides, low
HDL's), insulin resistance, fat redistribution and coronary artery disease. HIV viral
replication, anti-retroviral treatment regimens, lipids, glucose intolerance, host immune
response or a combination of factors may contribute to the increase in cardiovascular risk
factors. HIV positive patients, independent of the effect on lipids, appear to have
increased cardiovascular risk. Studies are not entirely consistent, but the most convincing
study to date, the D.A.D. study from EURO-SIDA, shows a 27% relative increased rate of
myocardial infarction per year of exposure over the first seven years of ART.
Lopinavir-ritonavir is one of the most commonly used antiretroviral therapy. It also
produces lipid abnormalities. Thus, an important part of the investigating factors
contributing to atherosclerosis would be to determine if this drug can adversely influence
endothelial cells in the absence of HIV infection or low CD4 counts. This would suggest
that this drug directly or indirectly could predispose to atherosclerosis. Endothelial
function is an important contributor to atherosclerosis. Invasive and non-invasive methods
to evaluate endothelial cell function have been validated as predictors of coronary artery
disease. These techniques have been used at NIH for clinical investigation for many years.
This protocol is designed to determine whether there is a pathologic effect on endothelial
function from the lopinavir/ritonavir. By measuring endothelial function in HIV
non-infected subjects both before and after four weeks of therapy, we will be able to
investigate whether the medications have a direct toxic effect on the endothelium.
Collection of metabolic data will allow us to evaluate whether endothelial function occurs
in conjunction or separate from lipoprotein and glucose metabolic changes. As ARV options
increase, it may be possible to choose specific regimens that may minimize acceleration of
cardiovascular risk factors associated with endothelial dysfunction, especially in patients
with other cardiovascular risk factors. These findings may help elucidate the
pathophysiology of premature cardiovascular disease in HIV positive patients and also plan
interventions to minimize endothelial dysfunction and subsequent cardiovascular disease.
Healthy by medical history and physical examination.
Negative serum pregnancy test for females.
Females willing to use two forms of birth control including barrier contraception during
period of study (lopinavir/ritonavir decreases ethinyl estradiol levels).
Able to provide informed consent.
Laboratory values on screening visit within: AST less than 40 units/liter, serum
creatinine less than 1.5mg/dl; CPK less than 387, hemoglobin greater than 11.0 g/dL
(females) or greater than 12.6 g/dL (males), platelets greater than 154,000/mm(3), total
bilirubin less than or equal to 1.5 mg/d
Total cholesterol less than 200 mg/dL, LDL cholesterol less than 160 mg/dL, HDL
cholesterol greater than 30mg/dL, triglycerides less than 200 mg/dL.
Non-smoker or not having smoked for the past 6 weeks.
Negative for HIV by ELISA within 4 weeks of study participation.
Concomitant therapy with any prescription, over-the-counter or alternative medication
except intermittent use of acetaminophen, non-steroidal anti-inflammatory medications,
loperamide or oral contraceptives.
Inability to obtain venous access for sample collection.
Presence of diabetes mellitus or fasting blood sugar greater than 126 mg/dL, or abnormal
oral glucose tolerance test (2 hour post blood sugar greater than 200 mg/dL).
Human immunodeficiency virus (HIV) infection.
Cardiac disease, congestive heart disease, coronary artery disease, angina, carotid
stenosis, peripheral vascular disease, cerebrovascular disease, myocardial disease,
clinically significant valvular heart disease.
Any other condition that may interfere with the interpretation of the study results or not
be in the best interest of the subject in the opinion of the investigator.
Hypertension (systolic blood pressure greater than 140 mmHg or diastolic blood pressure
greater than 90 mmHg) on screening visit.
Observed abnormalities on EKG tracings that are significant in the opinion of the
investigator (examples include, AV block, multifocal atrial tachycardia, frequent
premature ventricular contractions, etc.).
Hypotension (systolic blood pressure less than 80 mmHG).
Pregnant or breastfeeding female.
Inability to abstain from caffeine use (coffee, tea or soda) or alcohol for 12 hours prior
to a blood flow study until the conclusion of the study.
Heavy alcohol ingestion (4 or more drinks a day) or current substance abuse.
Hypo or hyper thyroidism.
Allergy to lidocaine.
History of hepatitis or other liver disease.