Intravenous Vitamin C: Role, Dosage, Administration, Benefits, and Safety Profile
Intravenous vitamin C should be administered at doses of 2-3 g/day for patients with critical illness, severe inflammation, or chronic oxidative stress conditions, with higher doses of 200 mg/kg/day for severe sepsis and respiratory failure. 1
Indications and Clinical Applications
Primary Indications:
- Critical illness: Sepsis, trauma, cardiac arrest, major surgery 1, 2
- Chronic oxidative stress conditions: Diabetes, heart failure, smoking, alcoholism, severe COPD 1
- Malabsorption syndromes: Short bowel syndrome, chronic dialysis 3, 1
- Severe infections: Particularly respiratory infections 1
- Scurvy: Clinical vitamin C deficiency 1
Specific Dosing Recommendations:
| Clinical Condition | Recommended Dose |
|---|---|
| Critical illness (general) | 2-3 g/day IV [1] |
| Severe sepsis/respiratory failure | 200 mg/kg/day for 4 days [1] |
| Continuous renal replacement therapy | 2-3 g/day IV [1] |
| Periprocedural cardiac surgery | 1-2 g/day for 5-7 days IV [1] |
| Clinical scurvy | 1 g/day for at least one week [1] |
| Parenteral nutrition (adults) | 100-200 mg/day [3] |
| Parenteral nutrition (preterm/term infants) | 15-25 mg/kg/day [3] |
Administration Methods
Intravenous Administration:
- Dilution: Dilute with normal saline or glucose solution to minimize adverse reactions 3
- Protection from degradation: Shield from light exposure during preparation and administration 3
- Storage: After plasma separation, samples should be stored at ultra-low temperature (-70 to -80°C) 3
- Compatibility: May be added to parenteral nutrition admixtures containing carbohydrates, lipids, amino acids, electrolytes and trace elements (verify compatibility) 4
Intramuscular Administration:
- Available as an alternative when IV access is not feasible
- Particularly useful in cases of malabsorption 3
Benefits and Mechanisms of Action
- Antioxidant function: Primary circulating antioxidant that attenuates oxidative stress 2
- Anti-inflammatory effects: Reduces systemic inflammation in critical illness 2
- Immune support: Enhances immune system function during infection 2
- Cofactor role: Essential for important mono and dioxygenase enzymes 2
- Vasopressor support: Recent studies suggest reduced vasopressor requirements in sepsis 2
Pharmacokinetics
- Plasma concentration: IV administration produces significantly higher plasma concentrations than oral administration 5
- Peak levels: 1.25 g oral dose produces mean plasma concentrations of 134.8 ± 20.6 μmol/L compared to 885 ± 201.2 μmol/L for the same IV dose 5
- Biological half-life: Approximately 30 minutes at high plasma levels 6
- Tissue uptake: Most cells contain vitamin C in millimolar concentrations, much higher than plasma levels 7
Safety Profile and Precautions
Contraindications:
- Renal insufficiency: Requires dose adjustment and monitoring 1
- Glucose-6-phosphate dehydrogenase deficiency: Risk of hemolysis 8
Adverse Effects:
- Common minor effects: Lethargy/fatigue, changes in mental status, vein irritation/phlebitis 8
- Potential serious effects: Oxalate renal stones with high doses 7
- Pro-oxidant effects: High doses may act as pro-oxidants rather than antioxidants 7
Monitoring:
- Renal function: Particularly important with high-dose therapy
- Plasma levels: Consider monitoring in critical illness to ensure therapeutic levels
- Electrolytes: Monitor for imbalances, particularly in patients receiving continuous infusions
Special Considerations
- Pregnancy: Limited data; use only when clearly indicated
- Pediatric dosing: Children weighing less than 10 kg should receive 1 ml of dissolved vitamin C mixture per kg body weight per day 4
- Drug interactions: May affect certain laboratory tests and interact with some medications
Common Pitfalls
- Route of administration confusion: Oral vitamin C produces tightly controlled plasma concentrations that may be insufficient for therapeutic effects in critical illness 5
- Inadequate dosing: Failure to provide sufficient doses for clinical condition
- Improper storage/handling: Vitamin C degrades rapidly if not properly protected from light, heat, and oxygen 3
- Monitoring deficiencies: Failure to monitor for potential adverse effects with high-dose therapy
Remember that while vitamin C supplementation is generally safe, high-dose IV therapy should be administered under appropriate medical supervision with consideration of the patient's overall clinical condition and comorbidities.