IMMUN ACTIVE + D3 DENK POWDER (Each stick contains Vit D3/Vit C/Zinc/Selenium/L-histidine 11.5mg/300mg/10mg/50ug/50mg)

Indications

• Rheumatoid arthritis
• Allergic diseases
• Ulcers
• Anemia

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations.

Adults: Refer to the BNF for specific dosing guidelines.

Mechanism of action

The exact actions of supplemental L-histidine are not fully understood, but it is postulated to have immunomodulatory and antioxidant properties. It serves as the precursor for histamine, which can enhance suppressor T cell activity and potentially down-regulate the production of reactive oxygen species in immune cells. This may confer benefits in conditions like rheumatoid arthritis, where oxidative stress is a concern.

Pharmacodynamics

L-histidine is abundant in hemoglobin and contributes to various bodily functions. It has been clinically associated with treating rheumatoid arthritis, allergic diseases, ulcers, and anemia. Deficiencies in L-histidine can lead to complications such as impaired hearing. Its metabolites, particularly histamine, exhibit immunomodulatory effects and antioxidant capabilities.

Pharmacokinetics

L-histidine is absorbed through the gastrointestinal tract, and its bioavailability can be influenced by dietary intake. Once ingested, it is incorporated into proteins and utilized in various metabolic pathways, including histidine biosynthesis and tRNA charging. The metabolism of L-histidine involves its conversion to histamine, which subsequently participates in numerous physiological processes.

Pregnancy

There is limited data on the use of L-histidine during pregnancy. Consult healthcare professionals.

Breast-feeding

Limited information is available on the excretion of L-histidine in human milk. Consult healthcare professionals before use.

Storage

Store in a cool, dry place, away from direct sunlight. Keep out of reach of children.

Formulations

• L-histidine powder
• L-histidine capsules
• L-histidine tablets

Indications

• Selenium deficiency
• Supportive therapy in conditions requiring antioxidant support
• Potential adjunct in cancer prevention strategies

Dosage

Children: Refer to BNF for Children for specific dosing information.

Adults: Initially 100–500 micrograms daily, adjusted according to response and serum levels.

Mechanism of action

Selenium is metabolized to selenophosphate and selenocysteine, which are essential for the synthesis of selenoproteins. This process involves the incorporation of selenium into proteins through a specialized tRNA that recognizes the RNA sequence UGA, which is facilitated by SECIS structures and SBP-2 proteins. Key selenoproteins, like glutathione peroxidases, help protect cells from oxidative damage, thus playing a significant role in reducing the risk of diseases such as atherosclerosis and certain cancers.

Pharmacodynamics

Selenium is incorporated into various selenoproteins that perform essential functions, including antioxidant activity, redox balance, and regulation of thyroid hormones. Its role in antioxidant defense mechanisms is particularly important for protecting cells against reactive oxygen species (ROS). Selenium supplementation has been linked to improved immune function and potential cancer prevention.

Pharmacokinetics

Selenium is absorbed through the gastrointestinal tract, and its bioavailability can vary based on the source and form of selenium. Once absorbed, it is distributed to various tissues, where it is incorporated into selenoproteins. Selenium is primarily excreted through urine, and its half-life can depend on dietary intake and individual metabolism. Selenium status can be assessed through blood levels of selenoproteins and selenium itself.

Adverse effects

• Nausea
• Anaemia
• Aplastic anaemia
• Skin reactions
• Gastrointestinal disorders

Precautions

• Selenium supplementation should not be given unless there is good evidence of deficiency.
• Use caution in patients with a history of hypersensitivity to selenium or its compounds.

Pregnancy

Limited information is available regarding selenium supplementation during pregnancy. Consult specialist sources for guidance.

Breast-feeding

Limited information is available; the effect of selenium on copper levels in milk is conflicting, and its impact on the infant is unknown.

Storage

After opening, store in a refrigerator (2–8°C).

Formulations

• Tablets (e.g., L-Selenomethionine 200 micrograms, SelenoPrecise 100 micrograms)
• Capsules (e.g., Trientine dihydrochloride 250 mg)
• Injection solutions (e.g., Sodium selenite 50 micrograms per 1 ml)

Mechanism of action

Since the actions of supplemental L-histidine are unclear, any postulated mechanism is entirely speculative. However, some facts are known about L-histidine and some of its metabolites, such as histamine and trans-urocanic acid, which suggest that supplemental L-histidine may one day be shown to have immunomodulatory and/or antioxidant activities. Low free histidine has been found in the serum of some rheumatoid arthritis patients. Serum concentrations of other amino acids have been found to be normal in these patients. L-histidine is an excellent chelating agent for such metals as copper, iron and zinc. Copper and iron participate in a reaction (Fenton reaction) that generates potent reactive oxygen species that could be destructive to tissues, including joints. L-histidine is the obligate precursor of histamine, which is produced via the decarboxylation of the amino acid. In experimental animals, tissue histamine levels increase as the amount of dietary L-histidine increases. It is likely that this would be the case in humans as well. Histamine is known to possess immunomodulatory and antioxidant activity. Suppressor T cells have H2 receptors, and histamine activates them. Promotion of suppressor T cell activity could be beneficial in rheumatoid arthritis. Further, histamine has been shown to down-regulate the production of reactive oxygen species in phagocytic cells, such as monocytes, by binding to the H2 receptors on these cells. Decreased reactive oxygen species production by phagocytes could play antioxidant, anti-inflammatory and immunomodulatory roles in such diseases as rheumatoid arthritis. This latter mechanism is the rationale for the use of histamine itself in several clinical trials studying histamine for the treatment of certain types of cancer and viral diseases. In these trials, down-regulation by histamine of reactive oxygen species formation appears to inhibit the suppression of natural killer (NK) cells and cytotoxic T lymphocytes, allowing these cells to be more effective in attacking cancer cells and virally infected cells.

Pharmacodynamics

Is found abundantly in hemoglobin; has been used in the treatment of rheumatoid arthritis, allergic diseases, ulcers and anemia. A deficiency can cause poor hearing.

Mechanism of action

Selenium is first metabolized to selenophosphate and selenocysteine. Selenium incorporation is genetically encoded through the RNA sequence UGA. This sequence is recognized by RNA ste loop structures called selenocysteine inserting sequences (SECIS). These structures require the binding of SECIS binding proteins (SBP-2) to recognize selenocystiene. The specialized tRNA is first bound to a serine residue which is then enzymatically processed to a selylcysteyl-tRNA by selenocystiene sythase using selenophosphate as a selenium donor. Other unidentified proteins are required as part of the binding of this tRNA to the ribosome. Selenoproteins appear to be necessary for life as mice with the specialized tRNA gene knocked out exhibited early embryonic lethality. The most important selenoproteins seem to be the glutathione peroxidases and thioredoxin reductases which are part of the body's defenses againts reactive oxygen species (ROS). The importance of selenium in these anti-oxidant proteins has been implicated in the reduction of atherosclerosis by preventing the oxidation of low density lipoprotein. Selenium supplementation is also being investigated in the prevention of cancer and has been suggested to be beneficial to immune function. Converging data from epidemiological, ecological, and clinical studies have shown that selenium (Se) can decrease the risk for some types of human cancers. Induction of apoptosis is considered an important cellular event that can account for the cancer preventive effects of Se. Prior to occurrence of apoptosis, Se compounds alter the expression and/or activities of signaling molecules, mitochondria-associated factors, transcriptional factors, tumor suppressor genes, and cellular reduced glutathione. Mechanistic studies have demonstrated that the methylselenol metabolite pool has many desirable attributes of chemoprevention, whereas the hydrogen selenide pool with excess of selenoprotein synthesis can lead to DNA single-strand breaks. To elucidate the effects of Se on cytotoxic events, it should be remembered that the chemical forms and the dose of Se, and the experimental system used, are determinants of its biological activities. This mini-review focuses on elucidation of the molecular mechanisms of cancer prevention by Se with the apoptotic approach. /Selenium/ Selenium status can also influence thyroid hormone function via the deiodinase enzymes. Selenium is a critical component of the deiodinase enzymes, including iodothyronine 5'-deiodinases, which convert the prohormone thyroxine (T4) to the active circulating form, triiodothyronine (T3). Selenium is also a component of GPX, the main enzyme responsible for protecting thyroid cells against oxidative damage. GPX is involved in the detoxification of hydrogen peroxide, which is produced in the thyroid during the conversion of T4 to T3. /Selenium/ Selenium readily substitutes for sulfur in biomolecules and in many biochemical reactions, especially when the concentration of selenium is high and the concentration of sulfur is low in the organism. Inactivation of the sulfhydryl enzymes necessary for oxidative reactions in cellular respiration, through effects on mitochondrial and microsomal electron transport, might contribute to acute selenium toxicity. Selenium may have a role in hepatic heme metabolism that is related to GPX or lipid peroxidation. Selenocysteine is specifically found in some proteins (e.g., glutathione peroxidase); selenomethionine appears to randomly substitute for methionine in protein synthesis. This appears to be an additional mechanism for intermediate- or chronic-duration toxicity. Skin, hair, and nail damage are significant indicators of chronic selenium overexposure. The mechanism causing these integumentary effects is unclear, but could be related to the high selenium concentrations in these tissues as a consequence of the substitution of selenium for sulfur in certain amino acids, including the disulfide bridges that pr

Pharmacodynamics

Selenium is incorporated into many different selenoproteins which serve various functions throughout the body.