What are the uses and precautions of selenium-containing drugs?

Selenium-Containing Drugs: Uses and Precautions

Primary Clinical Uses

Selenium supplementation is essential for preventing deficiency in patients on parenteral nutrition, treating documented selenium deficiency, and managing specific high-loss states including burns, major trauma, and renal replacement therapy. 1

Nutritional Supplementation

• Parenteral nutrition patients require 60-100 mcg/day to normalize plasma selenium levels and prevent deficiency. 1, 2
• Patients on long-term enteral nutrition need monitoring as selenium deficiency may develop depending on the feeding product composition. 1
• Multivitamin supplements should contain selenium at government-recommended daily allowances for general prevention. 1
• Following malabsorptive bariatric procedures (BPD/DS), additional routine oral selenium supplementation may be needed to prevent deficiency. 1

High-Risk Clinical Scenarios Requiring Increased Doses

• Burns patients with high selenium losses benefit from 375 mcg/day IV, resulting in more rapid healing and fewer infections. 1, 2
• Major trauma and cardiac surgery patients may benefit from 275 mcg/day supplementation. 1, 2
• Patients receiving renal replacement therapy have increased losses and oxidative stress requiring increased amounts. 1
• Recently depleted patients may require up to 200 mcg/day (twice normal daily amount) with plasma selenium monitoring. 1, 2

Topical Selenium Sulfide

• Selenium sulfide 2.5% lotion is FDA-approved for treating tinea versicolor, seborrheic dermatitis of the scalp, and dandruff through its cytostatic effect on epidermal and follicular epithelial cells. 3

Specialized Indications

• Selenium supplementation in selenium-deficient patients with mild thyroid eye disease (TED) reduces inflammatory symptoms, possibly through antioxidant effects. 1
• Selenium deficiency is associated with increased incidence and virulence of viral infections. 1

Treatment Thresholds and Monitoring

When to Initiate Supplementation

Plasma selenium <0.4 mmol/L (<32 mcg/L) always triggers supplementation regardless of inflammatory status. 1, 2

• In patients without inflammation (CRP <20 mg/L), initiate supplementation when plasma selenium <0.75 mmol/L to prevent immune dysfunction. 1, 2
• Inflammation causes proportional reductions in plasma selenium: CRP 10-40 mg/L causes 15-25% decrease, CRP 41-80 mg/L causes ~35% decrease, and CRP >80 mg/L causes ~50% decrease. 1
• Measure both plasma selenium and CRP simultaneously at baseline in all patients likely to receive parenteral nutrition for more than two weeks. 2

Monitoring Protocol

• Repeat measurements every 3-6 months during ongoing parenteral nutrition, or more frequently based on initial results. 2
• For acute deficiency treatment, 100 mcg/day IV selenium for 2 weeks should restore blood levels and reduce symptoms. 1
• Infants on parenteral nutrition require 6 mcg/kg/day to prevent biochemical deficiency. 1, 2

Critical Precautions and Contraindications

Toxicity Risks

Upper toxicity limits occur at plasma selenium 6-12 mmol/L, and chronic overexposure is positively associated with type 2 diabetes and high-grade prostate cancer. 1, 2

• Selenium toxicity outbreaks have occurred from misformulated dietary supplements causing clinical selenosis. 1
• The narrow range between therapeutic and toxic doses makes uncontrolled self-medication dangerous. 4

Avoid High-Dose ICU Protocols

Do not use high-dose selenium (1000-4000 mcg/day) in ICU patients, as meta-analyses show no consistent benefit from massively increased selenium supply in this population. 2

Topical Selenium Sulfide Precautions

• Do not use selenium sulfide when acute inflammation or exudation is present, as increased absorption may occur. 3
• Contraindicated in patients allergic to any ingredients. 3
• Classified as Pregnancy Category C when used on body surfaces for tinea versicolor; should not ordinarily be used in pregnant women. 3
• Safety and effectiveness in infants have not been established. 3
• Adverse effects include skin irritation, occasional increased hair loss, and hair discoloration (minimized by thorough rinsing). 3

Formulation Considerations

• Selenomethionine is the predominant form in most supplements and is more easily absorbed than inorganic forms. 5, 6
• Sodium selenite and sodium selenate are used in multivitamin preparations, infant formulas, and protein mixes. 5
• Organic selenium compounds (selenomethionine, selenocysteine) demonstrate higher bioavailability compared to inorganic forms. 6
• Enteral supplements may be considered given selenium's high absorption, but IV route is more rapid for acute deficiency. 1