A convenient method for measuring blood ascorbate concentrations in patients receiving high-dose intravenous ascorbate

Pharmacokinetic Evaluation of Intravenous Vitamin C: A Classic Pharmacokinetic Study

PURPOSE

Intravenous vitamin C (IVC) is used in a variety of disorders with limited supporting pharmacokinetic data. Herein we report a pharmacokinetic study in healthy volunteers and cancer participants with IVC doses in the range of 1-100 g.

METHODS

A pharmacokinetic study was conducted in 21 healthy volunteers and 12 oncology participants. Healthy participants received IVC infusions of 1-100 g; oncology participants received IVC infusions of 25-100 g. Serial blood and complete urine samples were collected pre-infusion and for 24 h post-infusion. Pharmacokinetic parameters were computed using noncompartmental methods. Adverse events were monitored during the study.

RESULTS

In both cohorts, IVC exhibited first-order kinetics at doses up to 75 g. At 100 g, maximum concentration (C_max) plateaued in both groups, whereas area under the concentration-time curve (AUC) only plateaued in the healthy group. IVC was primarily excreted through urine. No saturation of clearance was observed; however, the mean 24-h total IVC excretion in urine for all doses was lower in oncology participants (89% of dose) than in healthy participants at 100 g (99%). No significant adverse events were observed; thus, maximum tolerated dose (MTD) was not reached.

CONCLUSION

IVC followed first-order pharmacokinetics up to 75 g and at up to 100 g had complete renal clearance in 24 h. IVC up to 100 g elicited no adverse effects or significant physiological/biochemical changes and appears to be safe. These data can be used to rectify existing misinformation and to guide future clinical trials.

REGISTRATION

ClinicalTrials.gov identifier number NCT01833351.

Therapeutic Efficacy of Pharmacological Ascorbate on Braf Inhibitor Resistant Melanoma Cells In Vitro and In Vivo

High-dose ascorbate paradoxically acts as a pro-oxidant causing the formation of hydrogen peroxide in an oxygen dependent manner. Tumor cells (in particular melanoma cells) show an increased vulnerability to ascorbate induced reactive oxygen species (ROS). Therefore, high-dose ascorbate is a promising pharmacological approach to treating refractory melanomas, e.g., with secondary resistance to targeted BRAF inhibitor therapy. BRAF mutated melanoma cells were treated with ascorbate alone or in combination with the BRAF inhibitor vemurafenib. Viability, cell cycle, ROS production, and the protein levels of phospho-ERK1/2, GLUT-1 and HIF-1α were analyzed. To investigate the treatment in vivo, C57BL/6NCrl mice were subcutaneously injected with D4M.3A (Braf^V600E) melanoma cells and treated with intraperitoneal injections of ascorbate with or without vemurafenib. BRAF mutated melanoma cell lines either sensitive or resistant to vemurafenib were susceptible to the induction of cell death by pharmacological ascorbate. Treatment of Braf^V600E melanoma bearing mice with ascorbate resulted in plasma levels in the pharmacologically active range and significantly improved the therapeutic effect of vemurafenib. We conclude that intravenous high-dose ascorbate will be beneficial for melanoma patients by interfering with the tumor’s energy metabolism and can be safely combined with standard melanoma therapies such as BRAF inhibitors without pharmacological interference.

Effect of high-dose intravenous vitamin C on point-of-care blood glucose level in septic patients: a retrospective, single-center, observational case series

INTRODUCTION

High-dose vitamin C is an essential adjunctive drug for sepsis treatment. This study aimed to determine if high-dose vitamin C could lead to erroneous point-of-care glucose testing results.

METHODS AND MATERIALS

This retrospective, single-center, observational case series involved septic patients treated with high-dose vitamin C. We monitored their paired point-of-care glucose and laboratory glucose levels for statistical analysis. The glucose oxidase-peroxidase colorimetric method and hexokinase spectrophotometric method were applied for point-of-care glucose and laboratory glucose monitoring, respectively. Parkes Consensus Error Grid Analysis was used to assess the clinical influence of paired blood glucose values. Subgroup analyses were conducted to explore the effect of different vitamin C dosages and various renal function levels on point-of-care glucose readings.

RESULTS

During a 3-year period, 82 eligible septic patients who accepted at least three days of high-dose vitamin C treatment were included in this study. Compliance with ISO15197:2013 criteria was met in 30 (36.59%) paired values, a proportion considerably lower than the minimum criteria for accuracy. Subgroup analysis showed that worse renal function or higher vitamin C dosage could lead to greater bias in point-of-care glucose readings; however, these inaccuracies rarely represented a clinical risk.

CONCLUSIONS

High-dose intravenous ascorbate acid infusion may interfere with point-of-care glucose testing results. Thus, laboratory glucose measurements are recommended for more accurate results. Nonetheless, the inaccuracies magnitude of point-of-care glucose readings does not represent a significant clinical risk when physicians alter clinical action based on these results.

Impact of High-Dose Intravenous Vitamin C for Treatment of Sepsis on Point-of-Care Blood Glucose Readings

BACKGROUND

Intravenous vitamin C therapy has been associated with reduced mortality in patients with sepsis. Of potential concern with this therapy are falsely elevated point-of-care (POC) blood glucose values vs laboratory analyzed (LA) readings. The purpose of this study was to compare POC and LA blood glucose measurements in patients receiving intravenous vitamin C therapy.

METHODS

All adults (≥18 years old) admitted from January 2017 to December 2018 who received at least two doses of intravenous vitamin C and had at least one paired blood glucose collection were eligible for inclusion. The primary endpoint was the accuracy in paired blood glucose values determined using the International Organization for Standardization (ISO) 15197:2013 criteria. Paired values were assessed for clinical impact using the Parkes consensus error grid analysis. A subgroup analysis was conducted to determine the impact of impaired renal function on outcomes.

RESULTS

Fourteen patients were included for analysis with 46 paired blood glucose levels. Compliance with ISO15197:2013 criteria was met in 34 (73.9%) paired values, which did not meet the minimum criteria for accuracy. Subgroup analysis showed that the paired values from patients with impaired renal function did not meet the minimum requirements for compliance, while those from patients without impaired renal function did. The Parkes error grid showed that the variation in POC measurements likely had minimal clinical impact.

CONCLUSIONS

Our study suggests that most patients receiving vitamin C for sepsis may still be monitored at POC with the glucose meter used in our study with minimal clinical impact.

Vitamin C zum Schutz vor SARS-CoV-2 und zur Behandlung von COVID-19

Die neue Erkrankung COVID-19 wird durch das Virus SARS-CoV-2 ausgelöst. Aufgrund der globalen pandemischen Ausbreitung und der hohen Anzahl an Todesfällen stellen diese Erkrankung und deren Folgen einen hochaktuellen Schwerpunkt für die Erforschung und Entwicklung neuer Therapieansätze dar. Einer dieser Ansätze ist eine Therapie mit Vitamin C, ein vielversprechendes Vorgehen, das von diversen Arbeitsgruppen weltweit verfolgt wird. Hierbei wird die Wirkung der verschiedenen Vitamin-C-Anwendungen sowohl als Prophylaxe wie auch als Therapie der COVID-19-Erkrankung untersucht. Aktuelle Daten der Literatur zeigen, dass Vitamin C ohne signifikante Nebenwirkungen auf verschiedene pathophysiologische Prozesse der SARS-CoV-2-Infektion wirkt. Die Interleukin-6- zu Interleukin-10-Ratio oder das Verhältnis der Neutrophilen- zu der Lymphozytenzahl kann als Verlaufsparameter verwendet werden, um die Dynamik des Entzündungsgeschehens und so das Ansprechen auf die Therapie zu beurteilen. In diesem Rahmen kann der Vitamin-C-Spiegel des Blutserums kostengünstig und schnell im Kapillarblut anhand des Glukosespiegels überwacht werden. (Stand: Mai 2020)

Intravenous Vitamin C for Cancer Therapy - Identifying the Current Gaps in Our Knowledge

The use of intravenous vitamin C (IVC) for cancer therapy has long been an area of intense controversy. Despite this, high dose IVC has been administered for decades by complementary health care practitioners and physicians, with little evidence base resulting in inconsistent clinical practice. In this review we pose a series of questions of relevance to both researchers and clinicians, and also patients themselves, in order to identify current gaps in our knowledge. These questions include: Do oncology patients have compromised vitamin C status? Is intravenous the optimal route of vitamin C administration? Is IVC safe? Does IVC interfere with chemotherapy or radiotherapy? Does IVC decrease the toxic side effects of chemotherapy and improve quality of life? What are the relevant mechanisms of action of IVC? What are the optimal doses, frequency, and duration of IVC therapy? Researchers have made massive strides over the last 20 years and have addressed many of these important aspects, such as the best route for administration, safety, interactions with chemotherapy, quality of life, and potential mechanisms of action. However, we still do not know the answers to a number of fundamental questions around best clinical practice, such as how much, how often and for how long to administer IVC to oncology patients. These questions point the way forward for both basic research and future clinical trials.

Retrospective Evaluation of Clinical Experience With Intravenous Ascorbic Acid in Patients With Cancer

BACKGROUND

Intravenous ascorbic acid (IV AA) has been used extensively in cancer patients throughout the United States. Currently, there are limited data on the safety and clinical effects of IV AA. The purpose of this study was to expand the current literature using a retrospective analysis of adverse events and symptomatic changes of IV AA in a large sample of cancer patients.

METHODS

We conducted a retrospective chart review of all patients receiving IV AA for cancer at the Thomas Jefferson University Hospital over a 7-year period. We assessed all reports of adverse events, laboratory findings, and hospital or emergency department admissions. We also reviewed quality-of-life data, including fatigue, nausea, pain, appetite, and mood.

RESULTS

There were 86 patients who received a total of 3034 doses of IV AA ranging from 50 to 150g. In all, 32 patients received only ascorbic acid as part of their cancer management (1197 doses), whereas 54 patients received ascorbic acid in conjunction with chemotherapy (1837 doses). The most common adverse events related to ascorbic acid were temporary nausea and discomfort at the injection site. All events reported in the ascorbic acid alone group were associated with less than 3% of the total number of infusions. Patients, overall, reported improvements in fatigue, pain, and mood while receiving ascorbic acid.

CONCLUSIONS

The results of this retrospective analysis support the growing evidence that IV AA is generally safe and well tolerated in patients with cancer, and may be useful in symptom management and improving quality of life.

High Dose Parenteral Ascorbate Inhibited Pancreatic Cancer Growth and Metastasis: Mechanisms and a Phase I/IIa study

Pancreatic cancer is among the most lethal cancers with poorly tolerated treatments. There is increasing interest in using high-dose intravenous ascorbate (IVC) in treating this disease partially because of its low toxicity. IVC bypasses bioavailability barriers of oral ingestion, provides pharmacological concentrations in tissues, and exhibits selective cytotoxic effects in cancer cells through peroxide formation. Here, we further revealed its anti-pancreatic cancer mechanisms and conducted a phase I/IIa study to investigate pharmacokinetic interaction between IVC and gemcitabine. Pharmacological ascorbate induced cell death in pancreatic cancer cells with diverse mutational backgrounds. Pharmacological ascorbate depleted cellular NAD+ preferentially in cancer cells versus normal cells, leading to depletion of ATP and robustly increased α-tubulin acetylation in cancer cells. While ATP depletion led to cell death, over-acetylated tubulin led to inhibition of motility and mitosis. Collagen was increased, and cancer cell epithelial-mesenchymal transition (EMT) was inhibited, accompanied with inhibition in metastasis. IVC was safe in patients and showed the possibility to prolong patient survival. There was no interference to gemcitabine pharmacokinetics by IVC administration. Taken together, these data revealed a multi-targeting mechanism of pharmacological ascorbate's anti-cancer action, with minimal toxicity, and provided guidance to design larger definitive trials testing efficacy of IVC in treating advanced pancreatic cancer.

Direct spectrophotometric measurement of supra-physiological levels of ascorbate in plasma

Background

Supra-physiological concentrations of ascorbate, vitamin C, in blood, greater than 1 mM, achieved through intravenous administration (IV), are being tested in clinical trials to treat human disease, e.g. cancer. These trials need information on the high levels of ascorbate achieved in blood upon IV administration of pharmacological ascorbate so appropriate clinical decisions can be made.

Methods

Here we demonstrate that in the complex matrix of human blood plasma supra-physiological levels of ascorbate can be quantified by direct UV spectroscopy with use of a microvolume UV–vis spectrophotometer.

Results

Direct quantitation of ascorbate in plasma in the range of 2.9 mM, lower limit of detection, up to at least 35 mM can be achieved without any sample processing, other than centrifugation.

Conclusions

This approach is rapid, economical, and can be used to quantify supraphysiological blood levels of ascorbate associated with the use of IV administration of pharmacological ascorbate to treat disease.

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A microvolume UV/Vis spectrometer can be used to determine supra-physiological levels of vitamin C in blood plasma directly.

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The effective molar extinction coefficient for the ascorbate monoanion in blood plasma is ε₂₆₅=13,000 M⁻¹ cm⁻¹.

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With appropriate sample handling, oxidation of AscH⁻ to DHA in the plasma is not a concern.

High-dose intravenous vitamin C combined with cytotoxic chemotherapy in patients with advanced cancer: a phase I-II clinical trial

Background

Biological and some clinical evidence suggest that high-dose intravenous vitamin C (IVC) could increase the effectiveness of cancer chemotherapy. IVC is widely used by integrative and complementary cancer therapists, but rigorous data are lacking as to its safety and which cancers and chemotherapy regimens would be the most promising to investigate in detail.

Methods and Findings

We carried out a phase I-II safety, tolerability, pharmacokinetic and efficacy trial of IVC combined with chemotherapy in patients whose treating oncologist judged that standard-of-care or off-label chemotherapy offered less than a 33% likelihood of a meaningful response. We documented adverse events and toxicity associated with IVC infusions, determined pre- and post-chemotherapy vitamin C and oxalic acid pharmacokinetic profiles, and monitored objective clinical responses, mood and quality of life. Fourteen patients were enrolled. IVC was safe and generally well tolerated, although some patients experienced transient adverse events during or after IVC infusions. The pre- and post-chemotherapy pharmacokinetic profiles suggested that tissue uptake of vitamin C increases after chemotherapy, with no increase in urinary oxalic acid excretion. Three patients with different types of cancer experienced unexpected transient stable disease, increased energy and functional improvement.

Conclusions

Despite IVC’s biological and clinical plausibility, career cancer investigators currently ignore it while integrative cancer therapists use it widely but without reporting the kind of clinical data that is normally gathered in cancer drug development. The present study neither proves nor disproves IVC’s value in cancer therapy, but it provides practical information, and indicates a feasible way to evaluate this plausible but unproven therapy in an academic environment that is currently uninterested in it. If carried out in sufficient numbers, simple studies like this one could identify specific clusters of cancer type, chemotherapy regimen and IVC in which exceptional responses occur frequently enough to justify appropriately focused clinical trials.

Trial Registration

ClinicalTrials.gov NCT01050621