FERBOVIT COMBINATION PRODUCT SUSPENSION

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)

Dosage

Children: Refer to the specific carbonyl compound for appropriate dosing guidelines in paediatric populations, as this also varies significantly.

Adults: Refer to the specific carbonyl compound for appropriate dosing guidelines, as doses can vary widely based on the compound's use and formulation.

Mechanism of action

Carbonyl compounds can undergo nucleophilic addition reactions due to the electrophilic nature of the carbonyl carbon. In biochemical pathways, carbonyl groups may interact with various nucleophiles, including amino acids in proteins, leading to modifications that can affect enzyme activity and cellular signaling pathways.

Pharmacodynamics

The pharmacodynamics of carbonyl compounds depend on their specific structure and the biological targets they interact with. Aldehydes and ketones can influence metabolic processes, including glycolysis and the Krebs cycle, through their roles as substrates or inhibitors. They may also participate in redox reactions, affecting cellular energy production and oxidative stress.

Pharmacokinetics

The pharmacokinetics of carbonyl compounds vary widely depending on their molecular structure, including absorption, distribution, metabolism, and excretion (ADME) properties. Many carbonyl compounds are lipophilic, which can influence their absorption and distribution in biological tissues. Metabolism often occurs through oxidation or reduction reactions, and excretion typically involves the renal system.

Pregnancy

Carbonyl compounds may pose risks to fetal development, and their use should be carefully evaluated during pregnancy.

Breast-feeding

It is advisable to avoid carbonyl compounds during breastfeeding unless the benefits outweigh the risks, as they may be excreted in breast milk.

Storage

Store in a cool, dry place away from light and moisture, and ensure containers are tightly sealed to prevent degradation.

Indications

• Vitamin deficiency
• Nutritional supplementation
• Prevention of certain diseases
• Supporting metabolic functions

Dosage

Children: Refer to specific guidelines for individual vitamins or consult a healthcare professional for personalized dosing recommendations.

Adults: Refer to specific guidelines for individual vitamins or consult a healthcare professional for personalized dosing recommendations.

Mechanism of action

Vitamins function primarily as coenzymes or precursors for enzyme cofactors in various metabolic pathways. For instance, B vitamins are involved in energy metabolism by assisting in the conversion of carbohydrates, fats, and proteins into energy. Vitamin C acts as an antioxidant, protecting cells from damage, and is also crucial for collagen synthesis. Fat-soluble vitamins like A are involved in vision and immune function, while vitamin D regulates calcium and phosphate metabolism.

Pharmacodynamics

Vitamins exert their effects by participating in biochemical reactions and influencing metabolic pathways. For example, vitamin A is vital for vision and immune response, while vitamin D is important for maintaining bone health through its role in calcium absorption. The effects of vitamins can vary significantly depending on their solubility, with water-soluble vitamins typically being excreted more readily than fat-soluble ones, which can accumulate in the body.

Pharmacokinetics

The absorption of vitamins varies; water-soluble vitamins are generally absorbed in the small intestine and excreted in urine, while fat-soluble vitamins require dietary fats for absorption and are stored in the liver and fatty tissues. The bioavailability of vitamins can be affected by dietary composition, age, and health status. Elimination half-lives also differ; for instance, vitamin C has a shorter half-life compared to vitamin A, which can persist in the body for longer periods.

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Constipation
• Headache
• Fatigue
• Allergic reactions

Interactions

• Fat-soluble vitamins (A, D, E, K) can accumulate and cause toxicity when taken in excess, especially with other supplements
• Certain medications (e.g., anticoagulants) may interact with vitamin K
• Vitamin C can enhance the absorption of iron supplements

Precautions

• Use caution in patients with kidney disease when taking vitamin D
• Monitor for signs of toxicity with high-dose vitamin supplementation
• Consider dietary sources of vitamins before recommending supplements

Pregnancy

Vitamins are generally considered safe during pregnancy when taken at recommended dosages. However, excessive intake, particularly of fat-soluble vitamins, should be avoided.

Breast-feeding

Most vitamins are safe during breastfeeding at recommended doses, but excessive amounts can affect breast milk composition.

Storage

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

Formulations

• Tablets
• Capsules
• Soft gels
• Powders
• Liquid solutions
• Chewable tablets

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.