20 research outputs found
Chronic Ventricular Cerebrospinal Fluid Sampling, Drug Injections, and Pressure Monitoring Using Subcutaneous Reservoirs in Monkeys
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Pharmacokinetics of zidovudine administered intravenously and orally in children with human immunodeficiency virus infection
Zidovudine pharmacokinetics were determined in 16 children with human immunodeficiency virus infection who were being treated intravenously and orally on an intermittent schedule (every 6 hours). The intravenous doses studied were 80 (n=3), 120 (n=4), and 160 (n=5) mg/m
2/dose, infused over 1 hour. Fourteen patients were monifored after an oral dose of zidovudine at 120 (n=2), 180 (n=7), or 240 (n=5) mg/m
2/dose. Zidovudine was assayed with a reverse-phase high-pressure liquid chromatography method. Zidovudine disapperance after intravenous administration was rapid and blexponential, with half-lives of 14 and 90 minutes and a total clearance of 641±161 ml/min/m
2. The volume of distribution at steady state was 45±28 L/m
2. These pharmacokinetics parameters are very similar to those reported in adults. When administered orally, zidovudine was rapidly absorbed. The fraction of the oral dose that was bioavailable was 0.68±0.25, so that a 50% increment in the dose, in the conversion from intravenous to oral administration, resulted in plasma zidovudine concentrations after oral dosing that were nearly identical to those achieved with the 1-hour intravenous infusion. However, a dose of 180 mg/m
2 given orally every 6 hours maintained plasma zidovudine concentrations in the target range of 1 μmol/L for less than half of the dosing interval. Other schedules, routes of administration, or oral drug formulations may have to be considered if sustained continuous exposure to micromolar zidovudine concentrations is desired
Assessing the future of diffuse optical imaging technologies for breast cancer management
Diffuse optical imaging (DOI) is a noninvasive optical technique that employs near-infrared (NIR) light to quantitatively characterize the optical properties of thick tissues. Although NIR methods were first applied to breast transillumination (also called diaphanography) nearly 80 years ago, quantitative DOI methods employing time- or frequency-domain photon migration technologies have only recently been used for breast imaging (i.e., since the mid-1990s). In this review, the state of the art in DOI for breast cancer is outlined and a multi-institutional Network for Translational Research in Optical Imaging (NTROI) is described, which has been formed by the National Cancer Institute to advance diffuse optical spectroscopy and imaging (DOSI) for the purpose of improving breast cancer detection and clinical management. DOSI employs broadband technology both in near-infrared spectral and temporal signal domains in order to separate absorption from scattering and quantify uptake of multiple molecular probes based on absorption or fluorescence contrast. Additional dimensionality in the data is provided by integrating and co-registering the functional information of DOSI with x-ray mammography and magnetic resonance imaging (MRI), which provide structural information or vascular flow information, respectively. Factors affecting DOSI performance, such as intrinsic and extrinsic contrast mechanisms, quantitation of biochemical components, image formation∕visualization, and multimodality co-registration are under investigation in the ongoing research NTROI sites. One of the goals is to develop standardized DOSI platforms that can be used as stand-alone devices or in conjunction with MRI, mammography, or ultrasound. This broad-based, multidisciplinary effort is expected to provide new insight regarding the origins of breast disease and practical approaches for addressing several key challenges in breast cancer, including: Detecting disease in mammographically dense tissue, distinguishing between malignant and benign lesions, and understanding the impact of neoadjuvant chemotherapies
Phase I study of high-dose piroxantrone with granulocyte colony-stimulating factor
PURPOSE: We performed a phase I trial of piroxantrone with and without granulocyte colony-stimulating factor (G-CSF) to determine whether the use of this cytokine would enable us to increase the dose-intensity of piroxantrone.
PATIENTS AND METHODS: Thirty-eight patients received 121 courses of piroxantrone administered once every 21 days. Initial patient cohorts received piroxantrone alone starting at 150 mg/m2 and the dose was escalated in subsequent patients until dose-limiting toxicity (DLT) was reached. Patient cohorts then received escalating doses of piroxantrone starting at 185 mg/m2 administered with G-CSF beginning day 2.
RESULTS: Dose-limiting neutropenia occurred in three of six patients treated with 185 mg/m2 piroxantrone; the maximum-tolerated dose (MTD) of piroxantrone alone was 150 mg/m2. Three of six patients treated with piroxantrone and G-CSF exhibited dose-limiting thrombocytopenia at 445 mg/m2; the MTD of piroxantrone with G-CSF was thus 355 mg/m2. Seven patients developed symptomatic congestive heart failure (CHF) at cumulative piroxantrone doses ranging from 855 to 2,475 mg/m2 and two have died of cardiotoxicity. Of these patients, six of seven had previously received doxorubicin. Other nonhematologic toxicity was mild.
CONCLUSION: The use of G-CSF results in a more than twofold increase in the MTD of piroxantrone. However, symptomatic cardiotoxicity is prominent, especially in patients who have received prior treatment with anthracyclines