What is the recommended preparation and administration of sodium thiosulfate for dialysis patients?

Sodium Thiosulfate Preparation and Administration in Dialysis Patients

For dialysis patients requiring sodium thiosulfate, the standard preparation is 12.5-25 g administered intravenously over 15 minutes to 1 hour, given 2-3 times weekly during the last hour of hemodialysis or immediately post-dialysis. 1, 2

Primary Indication in Dialysis Patients

Sodium thiosulfate in dialysis patients is primarily used for calciphylaxis (calcific uremic arteriolopathy), not for cyanide poisoning, which is the FDA-labeled indication 1, 2, 3. This represents off-label use with substantial clinical evidence supporting efficacy.

Standard Dosing Protocol for Calciphylaxis

Intravenous Administration (Most Common Route)

• Dose range: 12.5-25 g per session 2, 4
• Frequency: 2-3 times weekly, typically during or immediately after hemodialysis 2, 4
• Infusion rate: Administer over 15 minutes to 1 hour 1, 2
• Duration of therapy: Typically 5 weeks to 8 months, though some patients require up to 2 years of treatment 3, 4

Preparation Details

• Formulation: Sodium thiosulfate injection USP 12.5 g/50 mL (250 mg/mL) 1
• Administration timing: Given during the last hour of hemodialysis or immediately post-dialysis to minimize removal by dialysis 2
• IV line compatibility: Do NOT administer simultaneously with hydroxocobalamin through the same IV line due to chemical incompatibility 1

Pharmacokinetic Considerations Specific to Dialysis

Critical timing issue: Sodium thiosulfate has a markedly prolonged half-life of 478 minutes in anuric hemodialysis patients, with measurable drug levels persisting more than 50 hours after administration 2. This extended half-life justifies the 2-3 times weekly dosing schedule rather than daily administration.

Alternative Routes for Peritoneal Dialysis Patients

Intraperitoneal Administration

• Dose: 12.5-25 g administered 3-4 times weekly 4
• Dwell time: 12 hours to 3 months 4
• Major concern: 80% discontinuation rate due to adverse effects, including chemical peritonitis (20% mortality from this complication) 4
• Recommendation: Use with extreme caution; IV route preferred even in PD patients 4

Oral Maintenance Therapy

• Dose: 1500 mg twice daily 5, 4
• Use: As maintenance therapy after initial IV treatment course 5
• Cost advantage: CAD $45/month versus CAD $12,000/month for IV formulation 5
• Efficacy: Can stabilize or improve lesions after initial IV therapy 5

Monitoring Requirements

During Administration

• Blood pressure: Monitor continuously during infusion; decrease infusion rate if significant hypotension develops 1
• Acid-base status: Monitor for anion gap metabolic acidosis, which commonly develops but is generally well-tolerated 2

Post-Administration

• Duration: Monitor for 24-48 hours after administration for adequacy of oxygenation and perfusion 1
• Hemoglobin/hematocrit: Obtain when treatment is initiated 1

Common Adverse Effects and Management

• Nausea: Most common side effect, usually manageable 2
• Anion gap metabolic acidosis: Expected finding, typically does not require treatment discontinuation 2
• Hypotension: Reduce infusion rate if occurs 1
• Chemical peritonitis: Specific to IP administration in PD patients 4

Treatment Duration Algorithm

1. Initial phase: IV sodium thiosulfate 12.5-25 g three times weekly for minimum 3-6 months 2, 3
2. Assessment: Evaluate wound healing and clinical response at 6 months 3
3. Continuation criteria: If improving, continue IV therapy until complete wound healing achieved 3
4. Maintenance option: Consider transition to oral STS 1500 mg twice daily after initial IV course to prevent recurrence 5
5. Long-term therapy: Some patients require up to 2 years of treatment for complete disease control 3

Critical Pitfalls to Avoid

• Do not administer with hydroxocobalamin through same IV line due to chemical incompatibility 1
• Do not use IP route as first-line in PD patients due to high adverse effect rate (80%) and peritonitis risk 4
• Do not discontinue prematurely: Treatment requires months, not weeks, for optimal outcomes 3
• Do not ignore sulfite sensitivity: Product may contain trace sulfite impurities, though this should not deter emergency use 1

Vascular Calcification Prevention Context

Recent evidence suggests sodium thiosulfate may attenuate vascular calcification progression in maintenance hemodialysis patients at doses of 12.5-25 g per session, 2-3 times weekly for 3-6 months, though significant hip bone mineral density decline has been observed 6. This represents an emerging indication requiring further study.