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Selenious Acid (Monograph)

Drug class: Replacement Preparations
Chemical name: Selenium dioxide, monohydrate
Molecular formula: H2O3Se
CAS number: 7783-00-8

Medically reviewed by on Mar 29, 2023. Written by ASHP.


Selenium injection is a sterile, nonpyrogenic solution for use as an additive to solutions for total parenteral nutrition (TPN).

Each mL contains selenious acid 65.4 mcg (equivalent to elemental selenium 40 mcg/mL) and water for injection. pH may be adjusted with nitric acid to 1.8 to 2.4.

Uses for Selenious Acid

Selenium has the following uses:

Selenium injection is indicated for use as a supplement to intravenous solutions given for total parenteral nutrition (TPN). Administration of selenium in TPN solutions helps to maintain plasma selenium levels and to prevent depletion of endogenous stores and subsequent deficiency symptoms.

Selenious Acid Dosage and Administration


Selenium is available in the following dosage form(s) and strength(s):

Selenium injection containing selenious acid 65.4 mcg/mL (equivalent to elemental selenium 40 mcg/mL).


Selenium injection provides 40 mcg selenium/mL. For metabolically stable adults receiving TPN, the suggested additive dosage level is 20 to 40 mcg selenium/day. For pediatric patients, the suggested additive dosage level is 3 mcg/kg/day.

In adults with selenium deficiency states resulting from long-term TPN support, selenium as selenomethionine or selenious acid, administered intravenously at 100 mcg/day for a period of 24 and 31 days, respectively, has been reported to reverse deficiency symptoms without toxicity.

Aseptic addition of selenium injection to the TPN solution under laminar flow hood is recommended. Selenium is physically compatible with the electrolytes and other trace elements usually present in amino-acid/dextrose solution used for TPN. Frequent monitoring of plasma selenium levels is suggested as a guideline for subsequent administration. The normal whole blood range for selenium is approximately 10 to 37 mcg/100 mL.

Do not directly mix ascorbic acid injection with selenium containing parenteral products in the same syringe or vial, as this admixture may cause the formation of an insoluble precipitate.

Parenteral drug products should be inspected visually for particulate matter and discoloration whenever solution and container permit.

Cautions for Selenious Acid


Selenium injection should not be given undiluted by direct injection into a peripheral vein because of the potential for infusion phlebitis.



Selenium Toxicity

Selenium injection can be toxic if given in excessive amounts. Supplementation of TPN solution with selenium should be immediately discontinued if toxicity symptoms are observed. Frequent determination of plasma selenium levels during TPN support and close medical supervision are recommended.


Selenium injection is a hypotonic solution and should be administered in admixtures only.

Aluminum Toxicity

This product contains aluminum that may be toxic. Aluminum may reach toxic levels with prolonged parenteral administration if kidney function is impaired. Premature neonates are particularly at risk because their kidneys are immature, and they require large amounts of calcium and phosphate solutions, which contain aluminum.

Research indicates that patients with impaired kidney function, including premature neonates, who receive parenteral aluminum in amounts greater than 4 to 5 mcg/kg/day accumulate aluminum at levels associated with central nervous system and bone toxicity. Tissue loading may occur at even lower rates of administration.

General Precautions

As selenium is eliminated in urine and feces, selenium supplements may be adjusted, reduced, or omitted in renal dysfunction and/or gastrointestinal malfunction. In patients receiving blood transfusions, contribution from such transfusions should also be considered. Frequent selenium plasma level determinations are suggested as a guideline.

In animals, selenium has been reported to enhance the action of vitamin E and decrease the toxicity of mercury, cadmium, and arsenic.


Pregnancy category C. Selenium at high dose levels (15–30 mcg/egg) has been reported to have adverse embryological effects among chickens. There are, however, no adequate and well-controlled studies in pregnant women. Selenium injection should be used during pregnancy only if potential benefit justifies the potential risk to the fetus.

Presence of selenium in placenta and umbilical cord blood has been reported in humans.

Common Adverse Effects

The amount of selenium present in selenium injection is small. Symptoms of toxicity from selenium are unlikely to occur at the recommended dosage level.


Selenium is part of glutathione peroxidase, which protects cell components from oxidative damage due to peroxides produced in cellular metabolism.

Prolonged TPN support in humans has resulted in selenium deficiency symptoms which include muscle pain and tenderness. The symptoms have been reported to respond to supplementation of TPN solutions with selenium.

Pediatric conditions, Keshan disease, and kwashiorkor have been associated with low dietary intake of selenium. The conditions are endemic to geographical areas with low selenium soil content. Dietary supplementation with selenium salts has been reported to reduce the incidence of the conditions among affected children.

Normal blood levels of selenium in different human populations have been found to vary and depend on the selenium content of the food consumed.

Plasma selenium levels of 0.3 and 0.9 mcg/100 mL have been reported to produce deficiency symptoms in humans.

Selenium is eliminated primarily in urine. However, significant endogenous losses through feces also occur. The rate of excretion and the relative importance of two routes varies with the chemical form of selenium used in supplementation. Ancillary routes of elimination are lungs and skin.


Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

Selenious Acid


Dosage Forms


Brand Names



Injection, Solution

65.4 mcg /1 mL (equivalent to elemental selenium 40 mcg/1 mL)

Selenium Injection

American Regent Inc.

AHFS DI Essentials™. © Copyright 2023, Selected Revisions April 8, 2019. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

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