Intravenous Ascorbate as a Tumor Cytotoxic Chemotherapeutic Agent - 0 views
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There is a 10 — 100-fold greater content of catalase in normal cells than in tumor cells
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induce hydrogen peroxide generation
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Ascorbic acid and its salts (AA) are preferentially toxic to tumor cells in vitro (6 — 13) and in vivo
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related to intracellular hydrogen peroxide generation
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only be obtained by intravenous administration of AA
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Preferentially kills neoplastic cells
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Is virtually non-toxic at any dosage
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Does not suppress the immune system, unlike most chemotherapy agents
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Increases animal and human resistance to infectious agents by enhancing lymphocyte blastogenesis, enhancing cellular immunity, strengthening the extracellular matrix, and enhancing bactericidal activity of neutrophils and modulation of complement protein
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Strengthens the structural integrity of the extracellular matrix which is responsible for stromal resistance to malignant invasiveness
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1969, researchers at the NCI reported AA was highly toxic to Ehrlich ascites cells in vitro
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In 1977, Bram et al reported preferential AA toxicity for several malignant melanoma cell lines, including four human-derived lines
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Noto et al reported that AA plus vitamin K3 had growth inhibiting action against three human tumor cell lines at non-toxic levels
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Metabolites of AA have also shown antitumor activity in vitro
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The AA begins to reduce cell proliferation in the tumor cell line at the lowest concentration, 1.76 mg/dl, and is completely cytotoxic to the cells at 7.04 mg/dl
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the normal cells grew at an enhanced rate at the low dosages (1.76 and 3.52 mg/dl)
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preferential toxicity of AA for tumor cells. >95% toxicity to human endometrial adenocarcinoma and pancreatic tumor cells (ATCC AN3-CA and MIA PaCa-2) occurred at 20 and 30 mg/dl, respectively.
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No toxicity or inhibition was demonstrated in the normal, human skin fibroblasts (ATCC CCD 25SK) even at the highest concentration of 50 mg/dl.
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the use of very high-dose intravenous AA for the treatment of cancer was proposed as early as 1971
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Cameron and Pauling have published extensive suggestive evidence for prolonged life in terminal cancer patients orally supplemented (with and without initial intravenous AA therapy) with 10 g/day of AA
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AA, plasma levels during infusion were not monitored,
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the long-term, oral dosage used in those experiments (10 g/day), while substantial and capable of producing immunostimulatory and extracellular matrix modulation effects, was not high enough to achieve plasma concentrations that are generally cytotoxic to tumor cells in culture
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This low cytotoxic level of AA is exceedingly rare
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5 — 40 mg/dl of AA is required in vitro to kill 100% of tumor cells within 3 days. The 100% kill levels of 30 mg/dl for the endometrial carcinoma cells and 40 mg/dl for the pancreatic carcinoma cells in Figure 2 are typical
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normal range (95% range) of 0.39-1.13 mg/dl
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1 h after beginning his first 8-h infusion of 115 g AA (Merit Pharmaceuticals, Los Angeles, CA), the plasma AA was 3.7 mg/dl and at 5 h was 19 mg/dl. During his fourth 8-h infusion, 8 days later, the 1 h plasma level was 158 mg/dl and 5 h was 185 mg/dl
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plasma levels of over 100 mg/dl have been maintained in 3 patients for more than 5 h using continuous intravenous infusion
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In rare instances of patients with widely disseminated and rapidly proliferating tumors, intravenous AA administration (10 — 45 g/day) precipitated widespread tumor hemorrhage and necrosis, resulting in death
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Although the outcomes were disastrous in these cases, they are similar to the description of tumor-necrosis-factor-induced hemorrhage and necrosis in mice (52) and seem to demonstrate the ability of AA to kill tumor cells in vivo.
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toxic effects of AA on one normal cell line were observed at 58.36 mg/dl and the lack of side effects in patients maintaining >100 mg/dl plasma levels
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Although it is very rare, tumor necrosis, hemorrhage, and subsequent death should be the highest priority concern for the safety of intravenous AA for cancer patients.
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Klenner, who reported no ill effects of dosages as high as 150 g intravenously over a 24-h period
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Cathcart (55) who describes no ill effects with doses of up to 200 g/d in patients with various pathological conditions
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following circumstances: renal insufficiency, chronic hemodialysis patients, unusual forms of iron overload, and oxalate stone formers
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Screening for red cell glucose-6-phosphate dehydrogenase deficiency, which can give rise to hemolysis of red blood cells under oxidative stress (57), should also be performed
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any cancer therapy should be started at a low dosage to ensure that tumor hemorrhage does not occur.
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patient is orally supplementing between infusions
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a scorbutic rebound effect can be avoided with oral supplementation. Because of the possibility of a rebound effect, measurement of plasma levels during the periods between infusions should be performed to ensure that no such effect takes place
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Every effort should be made to monitor plasma AA levels when a patient discontinues intravenous AA therapy.
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Older study, 1995, but shows the long-standing evidence that IVC preferentially is cytotoxic to cancer cells.`