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Evaluation of intracellular ascorbate deficiency and the cytotoxicity of sulfamethoxazole nitroso in healthy and HIV‐infected subjects
Author(s) -
Trepanier L. A.,
Guzinski M. V.,
Maki J. E.,
Yoder A. R.,
Bajad S.,
Bellehumeur J. L.,
Beckwith M. D.,
Graziano F. M.
Publication year - 2004
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1016/j.clpt.2003.11.056
Subject(s) - cytotoxicity , peripheral blood mononuclear cell , metabolite , intracellular , pharmacology , chemistry , cytotoxic t cell , toxicity , medicine , in vitro , immunology , biochemistry
Sulfamethoxazole (SMX) hypersensitivity affects 20–50% of treated HIV patients. SMX‐nitroso (SMX‐NO), the cytotoxic metabolite thought to mediate these reactions, is non‐enzymatically reduced by ascorbate (AA). The purpose of these studies was to determine the relationship between intracellular AA deficiency (reported in HIV‐infection) and in vitro cytotoxicity in the presence of SMX metabolites (which has been used as a marker for sulfonamide hypersensitivity). Peripheral blood mononuclear cells (PBMC) were obtained from HIV‐positive patients and healthy controls. PBMC AA concentrations and SMX‐NO reduction were determined by HPLC. PBMC from each subject were also exposed to 0.1‐1.0 mM SMX‐NO for 2 h., followed by overnight incubation in media. Cytotoxicity was quantified using YO‐PRO‐1 ® fluorescence. In preliminary results from 22 subjects, intracellular AA was strongly correlated with PBMC reduction of SMX‐NO (r=0.73; P=0.0001). In addition, AA was depleted during exposure to SMX‐NO, with a strong linear correlation between nmoles SMX‐NO reduced and nmoles AA depleted (r=0.75; P<0.0001). There was a trend toward an inverse relationship between intracellular AA and cytotoxicity (r= ‐0.31; P=0.18), and between SMX‐NO reduction and cytotoxicity (r= ‐0.36; P=0.14), but the association was not significant in this preliminary sample. Additional patient recruitment is underway to further characterize the relationship between ascorbate deficiency and sulfonamide toxicity. Clinical Pharmacology & Therapeutics (2004) 75 , P15–P15; doi: 10.1016/j.clpt.2003.11.056