A Stabilizing Agent, PCA/DTPA, Improves Plasma Storage Life for the Chromsystems Vitamin C Assay up to Six Months.

The commonly used Chromsystems vitamin C (ascorbate) assay (Munich, Germany) has a sample storage life of five days at -20°C. Stabilizing agents have been successfully used to increase longevity; however, their suitability with this commercial assay is unclear. We investigated the compatibility of a stabilizing agent, perchloric acid/diethylenetriaminepentaacetic acid (PCA/DTPA), with the Chromsystems assay. Plasma was stored at -80°C, with or without PCA/DTPA. Storage up to six months was assessed through baseline and repeat analyses, stability was assessed by comparing paired non-stabilized and PCA/DTPA-stabilized plasma, and performance was assessed using allowable performance specifications of an external quality assurance program. Ascorbate concentration was significantly lower in non-stabilized plasma than in paired PCA/DTPA-stabilized plasma, with a proportional difference of 11% (P=0.01). All storage analysis results were within the allowable performance specifications. Storage at -80°C prevented plasma ascorbate oxidation; however, substantial oxidation occurred during sample processing. In conclusion, PCA/DTPA significantly reduces ascorbate oxidation, and PCA/DTPA-stabilized ascorbate plasma is compatible with the Chromsystems assay and stable for up to six months, when stored at -80°C.

Effect of Vitamin C, Hydrocortisone, and Thiamine vs Hydrocortisone Alone on Time Alive and Free of Vasopressor Support Among Patients With Septic Shock: The VITAMINS Randomized Clinical Trial.

Importance: It is unclear whether vitamin C, hydrocortisone, and thiamine are more effective than hydrocortisone alone in expediting resolution of septic shock. Objective: To determine whether the combination of vitamin C, hydrocortisone, and thiamine, compared with hydrocortisone alone, improves the duration of time alive and free of vasopressor administration in patients with septic shock. Design, Setting, and Participants: Multicenter, open-label, randomized clinical trial conducted in 10 intensive care units in Australia, New Zealand, and Brazil that recruited 216 patients fulfilling the Sepsis-3 definition of septic shock. The first patient was enrolled on May 8, 2018, and the last on July 9, 2019. The final date of follow-up was October 6, 2019. Interventions: Patients were randomized to the intervention group (n = 109), consisting of intravenous vitamin C (1.5 g every 6 hours), hydrocortisone (50 mg every 6 hours), and thiamine (200 mg every 12 hours), or to the control group (n = 107), consisting of intravenous hydrocortisone (50 mg every 6 hours) alone until shock resolution or up to 10 days. Main Outcomes and Measures: The primary trial outcome was duration of time alive and free of vasopressor administration up to day 7. Ten secondary outcomes were prespecified, including 90-day mortality. Results: Among 216 patients who were randomized, 211 provided consent and completed the primary outcome measurement (mean age, 61.7 years [SD, 15.0]; 133 men [63%]). Time alive and vasopressor free up to day 7 was 122.1 hours (interquartile range [IQR], 76.3-145.4 hours) in the intervention group and 124.6 hours (IQR, 82.1-147.0 hours) in the control group; the median of all paired differences was -0.6 hours (95% CI, -8.3 to 7.2 hours; P = .83). Of 10 prespecified secondary outcomes, 9 showed no statistically significant difference. Ninety-day mortality was 30/105 (28.6%) in the intervention group and 25/102 (24.5%) in the control group (hazard ratio, 1.18; 95% CI, 0.69-2.00). No serious adverse events were reported. Conclusions and Relevance: In patients with septic shock, treatment with intravenous vitamin C, hydrocortisone, and thiamine, compared with intravenous hydrocortisone alone, did not significantly improve the duration of time alive and free of vasopressor administration over 7 days. The finding suggests that treatment with intravenous vitamin C, hydrocortisone, and thiamine does not lead to a more rapid resolution of septic shock compared with intravenous hydrocortisone alone. Trial Registration: ClinicalTrials.gov Identifier: NCT03333278.

Pharmacokinetic data support 6-hourly dosing of intravenous vitamin C to critically ill patients with septic shock.

OBJECTIVES: To study vitamin C pharmacokinetics in septic shock. DESIGN: Prospective pharmacokinetic study. SETTING: Two intensive care units. PARTICIPANTS: Twenty-one patients with septic shock enrolled in a randomised trial of high dose vitamin C therapy in septic shock. INTERVENTION: Patients received 1.5 g intravenous vitamin C every 6 hours. Plasma samples were obtained before and at 1, 4 and 6 hours after drug administration, and vitamin C concentrations were measured by high performance liquid chromatography. MAIN OUTCOME MEASURES: Clearance, volume of distribution, and half-life were calculated using noncompartmental analysis. Data are presented as median (interquartile range [IQR]). RESULTS: Of the 11 participants who had plasma collected before any intravenous vitamin C administration, two (18%) were deficient (concentrations < 11 µmol/L) and three (27%) had hypovitaminosis C (concentrations between 11 and 23 µmol/L), with a median concentration 28 µmol/L (IQR, 11-44 µmol/L). Volume of distribution was 23.3 L (IQR, 21.9-27.8 L), clearance 5.2 L/h (IQR, 3.3-5.4 L/h), and half-life 4.3 h (IQR, 2.6-7.5 h). For the participants who had received at least one dose of intravenous vitamin C before sampling, T0 concentration was 258 µmol/L (IQR, 162- 301 µmol/L). Pharmacokinetic parameters for subsequent doses were a median volume of distribution 39.9 L (IQR, 31.4-44.4 L), clearance 3.6 L/h (IQR, 2.6-6.5 L/h), and half-life 6.9 h (IQR, 5.7-8.5 h). CONCLUSION: Intravenous vitamin C (1.5 g every 6 hours) corrects vitamin C deficiency and hypovitaminosis C and provides an appropriate dosing schedule to achieve and maintain normal or elevated vitamin C levels in septic shock.