Oral Nifedipine to Treat Iron Overload

Overview

This study will determine if nifedipine, a medication used to treat high blood pressure, can help treat iron overload, a condition in which the body contains too much iron. Iron overload can be caused by the body's inability to regulate iron or by medical treatments, such as multiple blood transfusions. Over time, it can cause problems with the liver, heart and glands. Treatments include reducing iron intake in the diet or removing the excess iron using medical therapies. Recently, nifedipine was found to cause iron loss in the urine of small animals. This study will see if the drug can increase the removal of iron into the urine in humans as well. People 18 years of age and older with iron overload may be eligible for this study to undergo the following procedures: Study Day 1 Participants come to the NIH Clinical Center for a medical history, physical examination, blood and urine tests, electrocardiogram (EKG) and echocardiogram (heart ultrasound). Study Day 2 Participants will collect three urine samples: one is collected over 4 hours, followed by a second over 4 hours. Both of these samples are collected at NIH in the outpatient day hospital. At home, a third urine sample will be collected over 16 hours. For 1 week before the collections, participants are asked not to drink tea or eat foods high in Vitamin C or iron. They are also asked not to take any iron chelating medications. Study Day 3 Participants repeat the same urine collections as on day 2. They collect a 4-hour urine sample at the outpatient day hospital at NIH. They will then take a 20-mg tablet of nifedipine, and remain in the clinic 4 hours for blood pressure monitoring. A second urine sample during this time. They then return home to collect the final 16-hour sample, which they bring to the clinic the following day. Again, they are instructed to avoid a diet high in vitamin C, iron rich foods, tea, and to avoid taking any iron chelating medications. ...

Iron overload is common worldwide. If left untreated, body iron overload leads to multiple organ abnormalities including hepatic, endocrine (diabetes) and cardiac failure. In patients with ineffective erythropoiesis, iron overload results from the combination of increased intestinal absorption and transfusion. Unfortunately, physiological means to remove excess iron are limited, and treatments are limited to therapeutic phlebotomy and chelation therapy. While phlebotomy is the preferred therapy for patients with hemochromatosis, therapy for anemic patients is largely limited to chelation drugs. Since those drugs are frequently inadequate, additional iron-reduction therapies are being sought. Based upon recently published data in a rodent model, the purpose of this study is to determine if nifedipine will increase iron excretion in the urine among humans with increased levels of iron. Volunteers will be given a single oral dose (20mg) of nifedipine. Iron level in collections of urine will be measured and compared before and after nifedipine to determine if there is an associated increase in urinary iron excretion.