SELENIOUS ACID
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SELENIOUS ACID (SELENIOUS ACID).
Selenious acid is a source of selenium, an essential trace element that is a component of glutathione peroxidase and other selenoproteins, which protect cells from oxidative damage by reducing hydrogen peroxide and organic hydroperoxides.
| Metabolism | Selenium from selenious acid is metabolized via reduction to hydrogen selenide, which is then methylated to form methylselenol and dimethylselenide, and ultimately excreted in urine and breath. |
| Excretion | Primarily renal; urinary excretion accounts for approximately 50-70% of elimination. Fecal excretion is minor (less than 10%). |
| Half-life | Terminal elimination half-life is approximately 11 hours for selenium; however, selenious acid itself is rapidly converted to selenide, with a half-life of less than 2 hours. Clinical context: Half-life may be prolonged in renal impairment. |
| Protein binding | Selenium is extensively bound to plasma proteins, primarily to albumin and selenoprotein P, with approximately 50-80% bound. |
| Volume of Distribution | Volume of distribution for selenium is approximately 0.3-0.5 L/kg, reflecting distribution into total body water and tissues. |
| Bioavailability | Oral bioavailability of selenium from selenious acid is approximately 80-100% but is highly dependent on formulation and dietary factors. Intravenous administration yields 100% bioavailability. |
| Onset of Action | Intravenous: Clinical effects (e.g., normalization of selenium levels) may occur within hours to days; antioxidant effects are likely rapid (minutes to hours) after administration. |
| Duration of Action | Duration of clinical effect is variable, typically days to weeks, as selenium is incorporated into selenoproteins. Repeat dosing may be needed for sustained repletion. |
Selenious acid: 100-200 mcg intravenously over 30 minutes once daily or as directed by clinical response and serum selenium levels.
| Dosage form | SOLUTION |
| Renal impairment | No specific dose adjustment recommended for renal impairment; monitor serum selenium levels. |
| Liver impairment | No specific dose adjustment recommended for hepatic impairment; monitor serum selenium levels. |
| Pediatric use | Children: 2-3 mcg/kg intravenously over 30 minutes once daily, not to exceed 200 mcg daily; adjust based on serum selenium levels. |
| Geriatric use | Elderly patients: No specific dose adjustment; use caution due to potential renal/hepatic decline and monitor selenium levels. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SELENIOUS ACID (SELENIOUS ACID).
| Breastfeeding | Selenium is excreted into breast milk. Selenious acid injection safety during breastfeeding is not well studied. The M/P ratio is not available. Supplemental selenium in usual dietary amounts is compatible with breastfeeding; high doses should be avoided. Decision to breastfeed should consider the mother's clinical need and potential risks to the infant. |
| Teratogenic Risk | Selenious acid is a source of selenium, an essential trace element. High selenium doses are teratogenic in animals. In humans, maternal selenium deficiency is associated with adverse outcomes; supplementation to correct deficiency is generally considered safe. No specific teratogenic risk profile by trimester is established. First trimester: theoretical risk of malformations with excessive intake. Second and third trimesters: no specific fetal risks reported with recommended doses. However, high maternal selenium levels may be associated with neonatal conjunctivitis and splenomegaly. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to selenium or any component of the formulation.","Severe selenium toxicity (selenosis)."]
| Precautions | ["Selenium toxicity may occur with excessive doses, leading to selenosis (hair loss, nail changes, garlic breath).","Use with caution in patients with renal impairment due to potential accumulation.","Monitor selenium plasma levels to avoid toxicity."] |
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| Fetal Monitoring | Monitor maternal selenium levels to avoid toxicity (target 70-150 mcg/L). Assess liver and renal function periodically. In prolonged use, monitor for signs of selenium toxicity: garlic breath, metallic taste, alopecia, nail changes, peripheral neuropathy. Fetal monitoring by ultrasound for growth and development is not routinely required but may be considered if toxicity suspected. |
| Fertility Effects | Selenium deficiency may impair fertility; supplementation to correct deficiency can improve fertility. High selenium intake may have adverse effects on sperm motility and morphology in males. In females, excess selenium may disrupt menstrual cycles and implantation. No specific studies on selenious acid injection impact on human fertility. |