PubMed · 7464930
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R Benesch. 1981-02-19. Antisckiling drugs and water structure.. https://doi.org/10.1038/289637a0
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Although it has been shown that hydroxyurea (HU) therapy produces measurable amounts of nitric oxide (NO) metabolites, including iron nitrosyl hemoglobin (HbNO) in patients with sickle cell disease, the in vivo mechanism for formation of these is not known. Much in vitro data and some in vivo data indicates that HU is the NO donor, but other studies suggest a role for nitric oxide synthase (NOS). In this study, we confirm that the NO-forming reactions of HU with hemoglobin (Hb) or other blood constituents is too slow to account for NO production measured in vivo. We hypothesize that, in vivo, HU is partially metabolized to hydroxylamine (HA), which quickly reacts with Hb to form methemoglobin (metHb) and HbNO. We show that addition of urease, which converts HU to HA, to a mixture of blood and HU, greatly enhances HbNO formation.
This report describes the sustained response of an Iranian girl with homozygous beta(0) thalassemia (IVS-II-1G-->A) to hydroxyurea (HU) and recombinant erythropoietin (rEPO). Since the start of this regimen 7 years ago, she has been transfusion-independent and her hemoglobin is maintained between 9.5-11.0 gm/dL. She is maintaining consistent growth around the 10th percentile for age and enjoys a good quality of life. She has not had any therapy-related adverse effects. This experience suggests that therapy with HU and rEPO may be useful long-term in some patients with beta thalassemia.
BACKGROUND: Sickle cell disease is one of the most common inherited diseases world wide. It is associated with life long morbidity and a reduced life expectancy. Hydroxyurea, a chemotherapeutic drug taken by mouth, raises fetal haemoglobin and, as such, is expected to ameliorate some of the clinical problems of sickle cell disease. OBJECTIVES: To assess the effects of hydroxyurea therapy in sickle cell disease patients of all types, of any age, regardless of setting. SEARCH STRATEGY: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group specialised register of controlled trials for haemoglobinopathies, which comprises references identified from comprehensive electronic database searches, hand-searching relevant journals, and hand-searching abstract books of conference proceedings. Date of the most recent search(es): November 2000. SELECTION CRITERIA: All randomised or quasi-randomised controlled trials comparing the use of oral hydroxyurea for one month or longer with placebo, standard therapy or other interventions for the treatment of patients with sickle cell disease. DATA COLLECTION AND ANALYSIS: Both reviewers independently assessed trial quality and extracted data from the two studies included. MAIN RESULTS: Twenty trials were found of which two trials, which reported results from a total of 324 adults and children were suitable for inclusion in the review. From the data provided in the published reports only one study (the MSH study to the United States of America) could be analysed. This study showed marked differences in favour of hydroxyurea treatment as compared with placebo in terms of annual crisis rate, use of transfusions, and life-threatening complications (in particular, the acute sickle chest syndrome). No serious adverse effects were reported from either study. REVIEWER'S CONCLUSIONS: While hydroxyurea appears both effective and safe in the severely affected SS adults over a two year period; further studies are required to elucidate its role in other patient groups and for other conditions.