[Development and Assessment of a New Oral Selenium Fast-disintegrating Tablets].

Selenium is an essential trace element and its deficiency causes myositis, myocardial damage, and other symptoms. Patients receiving long-term intravenous nutrition or tube-feeding in particular are deficient in essential trace elements, including selenium, and require regular supplementation. In Japan, injectable selenium-containing products are listed on the National Health Insurance drug price list, and oral solutions are prepared and used in hospitals. However, these formulations have problems related to preservation and require complicated administration procedures. In this study, we developed a new fast-disintegrating tablet formulation of selenium, using SmartEx® (D-mannitol·low substituted hydroxypropylcellulose (L-HPC)·fully hydrolyzed polyvinyl alcohol (PVA) mixture) as a coprocessing additive, that can be administered orally or by feeding tube. The tablet formulation had excellent disintegrable capability, sufficient hardness, and did not cause tube blockage when administered in the simple suspension method. In addition, the tablet formulation showed no changes in properties in an accelerated test without packaging for 42 d, indicating that it could be stored for a long period. Fast-disintegrating tablets prepared with SmartEx® are expected to improve the adherence and quality of life of patients who require selenium supplementation.

Effect of selenium-deficient diet on tubular epithelium in normal rats.

Selenium (Se) deficiency reduces glutathione peroxidase (GPx) activity, resulting in increased oxidative stress. We examined how Se deficiency induces renal injury via oxidative stress over time during the Se-deficient period. Seventy-two male Wistar rats were divided into two groups and fed either a control or Se-deficient diet. Rats were sacrificed on weeks 1, 2, 4, 6, 9, and 12. Blood and urine samples were collected, and the kidneys were removed. Urinalysis was performed, and creatinine clearance (Ccr) was calculated. Expressions of cellular GPx (cGPx) and phospholipid hydroperoxidase GPx (PHGPx) mRNA and GPx activity were measured. Histology was evaluated by light microscopy with immunohistochemistry for 4-hydroxy-2-nonenal (HNE) and vimentin. The Se-deficient diet caused significant decreases in GPx activity and cGPx mRNA expression but no change in PHGPx mRNA, together with significant proteinuria and glucosuria and slight decline in Ccr. The Se-deficient diet induced calcification in the kidney and increased the distribution of HNE and vimentin immunostaining in proximal tubuli, particularly around the outer medulla stripe. However, the histological damage did not progress after 6 weeks of deficiency. Se deficiency induces proteinuria and glucosuria with renal calcification, which may be primarily induced by injury of proximal tubuli via oxidative stress.

Effect of selenium on Cisplatin-induced nephrotoxicity in rats.

Cisplatin (CP), a commonly used antineoplastic drug, is nephrotoxic. CP-induced nephrotoxicity involves oxidative pathways. A deficiency of selenium (Se) reduces glutathione peroxidase (GPx) activity resulting in oxidative stress. We investigated how Se deficiency or oral Se administration influences CP-induced nephrotoxicity. Thirty male Wistar rats were fed a Se-deficient or control diet for 4 weeks. Then they were given intraperitoneal (i.p.) CP alone, i.p. saline alone, or Se by gavage 24 and 1 h prior to i.p. CP. Blood and urine samples were collected and the kidneys were removed 5 days after CP treatment. Urinalysis, renal function, GPx activity, and expression of cellular GPx mRNA were measured. Histology was evaluated by light microscopy with immunohistochemistry for 4-hydroxy-2-nonenal (HNE), vimentin, and heme oxygenase (HO)-1. CP induced renal tubular damage with increased expression of vimentin, HO-1 and HNE staining, which represents lipid peroxidation. Se deficiency exacerbated CP-induced nephrotoxicity as shown by deterioration of the above parameters and depressed GPx activity and expression of GPx mRNA. Se treatment ameliorated CP-induced nephrotoxicity, but did not significantly improve renal function. These findings suggest that Se deficiency increases oxidative stress and enhances CP-induced nephrotoxicity, whereas oral Se treatment partially protects against the nephrotoxicity in rats.