What is the appropriate weekly maintenance dose of Vitamin D (arachitol inj, Vitamin D) after an initial dose of 600,000 IU?

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Last updated: January 8, 2026 • View editorial policy

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Maintenance Dosing After 600,000 IU Arachitol Injection

After a loading dose of 600,000 IU of vitamin D (arachitol injection), transition to a maintenance dose of at least 2,000 IU daily or 50,000 IU monthly to maintain optimal vitamin D levels above 30 ng/mL. 1

Understanding the Loading-to-Maintenance Transition

The 600,000 IU loading dose you've administered is appropriate for severe vitamin D deficiency and falls within guideline-recommended ranges for loading doses administered over several weeks 1, 2. However, 60,000 IU weekly is NOT the standard maintenance regimen recommended by major guidelines.

Evidence-Based Maintenance Protocols

Standard Maintenance Dosing

  • The preferred maintenance approach is 2,000 IU daily after completing the loading phase, as this dose is specifically recommended by the Endocrine Society and other major guidelines to maintain target levels of at least 30 ng/mL 1, 3

  • Alternative intermittent dosing: 50,000 IU monthly (equivalent to approximately 1,600 IU daily) is an acceptable maintenance regimen that can sustain optimal levels 1, 3

  • For elderly patients (≥65 years), a minimum of 800 IU daily is recommended, though higher doses of 700-1,000 IU daily are more effective for fall and fracture prevention 1

Why 60,000 IU Weekly Is Not Standard Maintenance

  • The standard loading regimen is 50,000 IU weekly for 8-12 weeks, NOT as ongoing maintenance 1, 3

  • Continuing high-dose weekly supplementation (60,000 IU) beyond the loading phase is excessive and not supported by guidelines for routine maintenance 1

  • Research demonstrates that 2,000 IU daily maintenance may be insufficient for some patients, but the solution is to increase to 3,000-4,000 IU daily, not to continue weekly high-dose therapy 4

Critical Monitoring Protocol

  • Recheck 25(OH)D levels 3 months after completing the loading dose to assess response and ensure adequate dosing, as vitamin D has a long half-life requiring this timeframe to reach steady-state 1, 3

  • Target serum 25(OH)D level: ≥30 ng/mL for anti-fracture efficacy, with an optimal range of 30-80 ng/mL and upper safety limit of 100 ng/mL 1, 5, 3

  • If levels remain below 30 ng/mL at 3 months, increase maintenance dose by 1,000-2,000 IU daily (or equivalent intermittent dose) 1

Essential Co-Interventions

  • Ensure adequate calcium intake of 1,000-1,500 mg daily from diet plus supplements if needed, as vitamin D enhances calcium absorption and adequate calcium is necessary for clinical response 1, 3

  • Calcium supplements should be taken in divided doses of no more than 600 mg at once for optimal absorption 1, 3

Special Population Considerations

Patients Requiring Higher Maintenance Doses

  • Malabsorption syndromes (post-bariatric surgery, inflammatory bowel disease, celiac disease): May require 2,000-5,000 IU daily maintenance, and intramuscular administration should be considered if oral supplementation fails 1, 5

  • Obesity: Vitamin D is sequestered in adipose tissue, potentially requiring maintenance doses of 3,000-6,000 IU daily 5

  • Chronic kidney disease (stages 3-4): Use standard nutritional vitamin D (cholecalciferol or ergocalciferol) at 2,000-4,000 IU daily; never use active vitamin D analogs (calcitriol, alfacalcidol) for nutritional deficiency 1

Safety Considerations

  • Daily doses up to 4,000 IU are generally safe for adults, with some evidence supporting up to 10,000 IU daily for several months without adverse effects 1, 5, 2

  • Avoid single ultra-high loading doses (>300,000-540,000 IU) as they have been associated with increased falls and fractures 1, 5

  • Vitamin D toxicity typically only occurs with prolonged daily doses exceeding 10,000 IU or serum levels >100 ng/mL 1, 5

Practical Algorithm

  1. Complete loading phase: Your 600,000 IU injection serves as the loading dose 1, 2

  2. Initiate maintenance immediately: Start 2,000 IU daily (or 50,000 IU monthly if compliance is a concern) 1, 3

  3. Monitor at 3 months: Measure 25(OH)D levels to confirm achievement of target ≥30 ng/mL 1, 3

  4. Adjust if needed: If levels remain <30 ng/mL despite compliance, increase to 3,000-4,000 IU daily 1, 5

  5. Long-term monitoring: Recheck annually once stable levels are achieved 1

Common Pitfalls to Avoid

  • Do not continue weekly high-dose supplementation indefinitely – this is a loading regimen, not maintenance 1

  • Do not assume 2,000 IU daily is sufficient for everyone – obese patients, those with malabsorption, and darker-skinned individuals often require higher doses 1, 5

  • Do not skip the 3-month follow-up measurement – individual response to vitamin D supplementation varies significantly due to genetic differences in metabolism 1

  • Do not use active vitamin D analogs (calcitriol, alfacalcidol, doxercalciferol, paricalcitol) to treat nutritional vitamin D deficiency 1

References

1
Guideline

Vitamin D Insufficiency Treatment Guidelines

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

3
Guideline

Vitamin D3 Dosage for Depression with Vitamin D Deficiency

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

4
Research

Maintenance Dose of Vitamin D: How Much Is Enough?

Journal of bone metabolism, 2018

5
Guideline

Vitamin D Supplementation Guidelines

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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