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Discover 21,724 clinical trials near Baltimore, Maryland. Find research studies in your area.
Showing 14801-14820 of 21,724 trials
NCT01851473
Background: \- Scientists are studying medications that may be useful in treating cocaine addiction. It is important in these studies to know whether study participants are always taking their medications as directed. This study will look at two chemicals to see if they can be used to determine whether participants are taking their medications as directed. Because acetazolamide and quinine can be measured in plasma and urine, they are good test subjects for this study. They will be given alone, and combined with intravenous cocaine. Objectives: \- To see how they body handles acetazolamide and quinine alone, and when combined with cocaine. Eligibility: \- Individuals between 18 and 50 years of age who have smoked or used IV cocaine for at least one year and at least three times per month during the three months prior to screening. Urine test positive for cocaine within the prior 6 months Design: * Participants will be screened with a physical exam and medical history. Blood and urine samples will also be collected. * This study will involve a 12-day inpatient stay at the National Institutes of Health. * On days 1, 5, and 10, participants will receive a dose of cocaine. Blood, urine, breath, and saliva samples will be collected up to 18 times a day for up to about 24 hours. * On days 2, 3, 4, and 5, participants will receive acetazolamide. Regular blood samples will be collected on Day 4. * Day 6 is a wash-out day with no drugs or blood tests. * On days 7, 8, 9, and 10, participants will receive quinine. Regular blood samples will be collected on Day 9. * On day 11, blood, urine, breath, and saliva samples will be collected in the early morning. Participants will be able to leave later in the day.
NCT01240616
Background: \- A brain circuit called the default network is the brain circuit that is active when the brain is at rest; that is, when individuals are not concentrating on specific tasks. Previous research has shown that the default network functions differently in people with schizophrenia and Alzheimer s disease, and may contribute to the problems with memory and concentration that can affect people who have these conditions. Studies have also shown that nicotine affects the default network, but more research is needed on the ways in which nicotinic receptors may change activity in these regions and thereby affect individuals ability to concentrate on specific tasks. Objectives: \- To determine whether and how nicotine and mecamylamine, a drug that blocks nicotinic receptors, affect the default network in nonsmokers in ways that improve thinking and concentration. Eligibility: * Healthy, right-handed volunteers between 21 and 50 years of age. * Volunteers must not have used any kind of tobacco product in the past 2 years. Design: * This study involves an initial screening visit, a training visit, and three testing visits. * Participants will be screened with a medical history and physical examination, as well as blood and urine samples and questions about smoking history. * Participants will have an initial training session to practice the tasks that will be done during magnetic resonance imaging scans at the testing visits. These tasks will test participants concentration and memory. * Participants will have three test sessions with the following combinations of study drugs: (1) a nicotine patch and a placebo capsule, (2) a placebo patch and a capsule of mecamylamine, or (3) a placebo patch and capsule. Different combinations will be given at each visit, and participants will not know which one they receive. * Participants will perform the same concentration and memory tasks at each testing visit, and will provide a blood sample after each visit to determine levels of nicotine and mecamylamine.