Doxercalciferol is a synthetic vitamin D2 analog that undergoes metabolic activation in vivo to form 1α,25-dihydroxyvitamin D2 (1α,25-(OH)2D2), a naturally occurring, biologically active form of vitamin D2. Doxercalciferol is indicated for the treatment of secondary hyperparathyroidism in patients with chronic kidney disease on dialysis, as well as for the treatment of secondary hyperparathyroidism in patients with Stage 3 or Stage 4 chronic kidney disease. Doxercalciferol is marketed under the brand name Hectorol by Genzyme Corporation, and is manufactured by Catalent Pharma Solutions, Inc.

Paricalcitol (Zemplar) is a synthetic vitamin D(2) analogue that inhibits the secretion of parathyroid hormone (PTH) through binding to the vitamin D receptor. It is approved in the US and in most European nations for intravenous use in the prevention and treatment of secondary hyperparathyroidism associated with chronic renal failure in adult, and in the US paediatric, patients. Paricalcitol effectively reduced elevated serum PTH levels and was generally well tolerated in children and adults with secondary hyperparathyroidism associated with chronic renal failure. In well designed clinical trials, paricalcitol was as effective as calcitriol and as well tolerated in terms of the incidence of prolonged hypercalcaemia and/or elevated calcium-phosphorus product (Ca x P). Preclinical and in vitro studies have demonstrated that paricalcitol's biological actions are mediated through binding of the vitamin D receptor, which results in the selective activation of vitamin D responsive pathways. Vitamin D and paricalcitol have been shown to reduce parathyroid hormone levels by inhibiting PTH synthesis and secretion.

Calcitriol is vitamin D3. Vitamin D is important for the absorption of calcium from the stomach and for the functioning of calcium in the body. Calcitriol is used to treat hyperparathyroidism (overactive parathyroid glands) and metabolic bone disease in people who have chronic kidney failure and are not receiving dialysis. Calcitriol is also used to treat calcium deficiency (hypocalcemia). The early signs and symptoms of vitamin D intoxication associated with hypercalcemia include: weakness, headache, somnolence, nausea, vomiting, dry mouth, constipation, muscle pain, bone pain and metallic taste. Cholestyramine has been reported to reduce intestinal absorption of fatsoluble vitamins; as such it may impair intestinal absorption of Calcitriol. Ketoconazole may inhibit both synthetic and catabolic enzymes of calcitriol.

Leucovorin is a compound similar to folic acid, which is a necessary vitamin. It has been around and in use for many decades. Leucovorin is a medication frequently used in combination with the chemotherapy drugs fluoruracil and methotrexate. Leucovorin is not a chemotherapy drug itself, however it is used in addition to these chemotherapy drugs to enhance anticancer effects (with fluorouracil) or to help prevent or lessen side effects (with methotrexate). Leucovorin is also used by itself to treat certain anemia problems when folic acid deficiency is present.

Levoleucovorin is the pharmacologically active isomer of leucovorin or 5-formyl tetrahydrofolic acid, a folate analog . Levoleucovorin does not require reduction by the enzyme dihydrofolate reductase in order to participate in reactions utilizing folates as a source of “onecarbon” moieties. Administration of levoleucovorin can counteract the therapeutic and toxic effects of folic acid antagonists such as methotrexate, which act by inhibiting dihydrofolate reductase. Levoleucovorin can enhance the therapeutic and toxic effects of fluoropyrimidines used in cancer therapy such as 5-fluorouracil. 5-fluorouracil is metabolized to 5-fluoro-2'-deoxyuridine-5'-monophosphate (FdUMP), which binds to and inhibits thymidylate synthase (an enzyme important in DNA repair and replication). Levoleucovorin is readily converted to another reduced folate, 5,10-methylenetetrahydrofolate, which acts to stabilize the binding of FdUMP to thymidylate synthase and thereby enhances the inhibition of this enzyme. Fusilev® (levoleucovorin) is approved by FDA for i) rescue after high-dose methotrexate therapy in osteosarcoma, ii) diminishing the toxicity and counteracting the effects of impaired methotrexate elimination and of inadvertent overdosage of folic acid antagonists and iii) in combination chemotherapy with 5-fluorouracil in the palliative treatment of patients with advanced metastatic colorectal cancer.

Ascorbic acid (vitamin C) is a water-soluble vitamin. It occurs as a white or slightly yellow crystal or powder with a slight acidic taste. Ascorbic acid is an electron donor, and this property accounts for all its known functions. As an electron donor, ascorbic acid is a potent water-soluble antioxidant in humans. Ascorbic acid acts as an antioxidant under physiologic conditions exhibiting a cross over role as a pro-oxidant in pathological conditions. Oxidized ascorbic acid (dehydroascorbic acid (DHA) directly inhibits IkappaBalpha kinase beta (IKKbeta) and IKKalpha enzymatic activity in vitro, whereas ascorbic acid did not have this effect. These findings define a function for vitamin C in signal transduction other than as an antioxidant and mechanistically illuminate how vitamin C down-modulates NF-kappaB signaling. Vitamin C is recommended for the prevention and treatment of scurvy. Its parenteral administration is desirable for patients with an acute deficiency or for those whose absorption of orally ingested ascorbic acid (vitamin c) is uncertain. Symptoms of mild deficiency may include faulty bone and tooth development, gingivitis, bleeding gums, and loosened teeth. Febrile states, chronic illness, and infection (pneumonia, whooping cough, tuberculosis, diphtheria, sinusitis, rheumatic fever, etc.) increase the need for ascorbic acid (vitamin c). Hemovascular disorders, burns, delayed fracture and wound healing are indications for an increase in the daily intake.

Pyridoxine is the 4-methanol form of vitamin B6 and is converted to pyridoxal 5-phosphate in the body. Vitamin B6 (pyridoxine) is a water-soluble vitamin used in the prophylaxis and treatment of vitamin B6 deficiency and peripheral neuropathy in those receiving isoniazid (isonicotinic acid hydrazide, INH). Vitamin B6 has been found to lower systolic and diastolic blood pressure in a small group of subjects with essential hypertension. Hypertension is another risk factor for atherosclerosis and coronary heart disease. Another study showed pyridoxine hydrochloride to inhibit ADP- or epinephrine-induced platelet aggregation and to lower total cholesterol levels and increase HDL-cholesterol levels, again in a small group of subjects. Vitamin B6, in the form of pyridoxal 5'-phosphate, was found to protect vascular endothelial cells in culture from injury by activated platelets. Endothelial injury and dysfunction are critical initiating events in the pathogenesis of atherosclerosis. Human studies have demonstrated that vitamin B6 deficiency affects cellular and humoral responses of the immune system. Vitamin B6 deficiency results in altered lymphocyte differentiation and maturation, reduced delayed-type hypersensitivity (DTH) responses, impaired antibody production, decreased lymphocyte proliferation and decreased interleukin (IL)-2 production, among other immunologic activities. Used for the treatment of vitamin B6 deficiency and for the prophylaxis of isoniazid-induced peripheral neuropathy.

Panthenol (pantothenol) is an alcohol form of the B5 vitamin pantothenic acid. It easily penetrates the skin retaining water and is a humectant, emollient and moisturizer. Panthenol mitigates signs of inflammation and stimulates epithelization. Panthenol comes in two enantiomers, D and L. Only D-panthenol (dexpanthenol) is biologically active, however both forms have moisturizing properties. Because of the ability to attract and hold moisture panthenol is used in skincare products as a humectant. It also has a role as provitamin (called pro-vitamin B5) and is used as a vitamin supplement in complex ( M.V.I. ADULT injection, Hospira Worldwide, Inc.) and alone, and as a cholinergic drug. Panthenol is a highly viscous transparent liquid at room temperature, but salts of pantothenic acid (sodium pantothenate) are powders (typically white). It is soluble in water, alcohol, propylene glycol, ether and chloroform, and slightly soluble in glycerin. Panthenol mixes readily with many different types of ingredients, making it a versatile ingredient to be used in formulas because it improves skin’s barrier function and maintains the proliferation of fibroblasts. In organisms it is quickly oxidized to pantothenate (pantothenic acid). Defficiency of Vitamin B5 results in many dermatological disorder. Due to the fact that only D-Panthenol is converted to Vitamin B5 and not L-Panthenol, the racemic mixture of D- and L- panthenol (DL-panthenol) has only half of the physiological activity of the D-Panthenol. These include stimulation of epithelisation, wound healing effect and anti-infl ammatory effect. Panthenol is FDA approved for cosmetic use and comes either in D form, or as a racemic mixture. It is also in the FDA list of over-the-counter drug products that are not generally recognized as safe and effective or are misbranded: as "Insect Bite and Sting Drug Products" and "Poison Ivy, Poison Oak, and Poison Sumac Drug Products".

Folic Acid is a B complex vitamin containing a pteridine moiety linked by a methylene bridge to para-aminobenzoic acid, which is joined by a peptide linkage to glutamic acid. Conjugates of Folic Acid are present in a wide variety of foods, particularly liver, kidneys, yeast and leafy green vegetables. Commercially available Folic Acid is prepared synthetically. Folic Acid occurs as a yellow or yellowish-orange crystalline powder and is very slightly soluble in water and insoluble in alcohol. Aqueous solutions of Folic Acid are heat sensitive and rapidly decompose in the presence of light and/or riboflavin; solutions should be stored in a cool place protected from light. Folic Acid is effective in the treatment of megaloblastic anemias due to a deficiency of Folic Acid (as may be seen in tropical or nontropical sprue) and in anemia of nutritional origin, pregnancy, infancy, or childhood. Folic Acid is relatively nontoxic in man. Rare instances of allergic responses to Folic Acid preparations have been reported and have included erythema, skin rash, itching, general malaise, and respiratory difficulty due to bronchospasm. Endocyte is developing an intravenous (IV) formulation of folic acid, called Neocepri®, which is intended for the diagnosis of positive folate receptor-positive status in patients with ovarian cancer when administered prior to the radioactive medicine, technetium Tc99m Etarfolatide. The benefits of Neocepri® are its ability to reduce the background activity observed on single photon emission computed tomography (SPECT) imaging in most normal, nontarget tissues (e.g. intestines, liver, kidney, spleen), thereby improving the image quality of the scans. The product had been granted orphan drug designation in the EU. Endocyte had filed a conditional marketing authorization application (CMA) with the European Medicines Agency (EMA) for Neocepri®.

Cyanocobalamin (commonly known as Vitamin B12) is the most chemically complex of all the vitamins. Cyanocobalamin's structure is based on a corrin ring, which, although similar to the porphyrin ring found in heme, chlorophyll, and cytochrome, has two of the pyrrole rings directly bonded. The central metal ion is Co (cobalt). Cyanocobalamin is naturally found in foods including meat (especially liver and shellfish), eggs, and milk products.Vitamin B12 is essential to growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis. Cells characterized by rapid division (e.g., epithelial cells, bone marrow, myeloid cells) appear to have the greatest requirement for vitamin B12. Vitamin B12 can be converted to coenzyme B12 in tissues, and as such is essential for conversion of methylmalonate to succinate and synthesis of methionine from homocysteine, a reaction which also requires folate. In the absence of coenzyme B12, tetrahydrofolate cannot be regenerated from its inactive storage form, 5- methyltetrahydrofolate, and a functional folate deficiency occurs. Vitamin B12 also may be involved in maintaining sulfhydryl (SH) groups in the reduced form required by many SH-activated enzyme systems. Through these reactions, vitamin B12 is associated with fat and carbohydrate metabolism and protein synthesis. Vitamin B12 deficiency results in megaloblastic anemia, GI lesions, and neurologic damage that begins with an inability to produce myelin and is followed by gradual degeneration of the axon and nerve head. Cyanocobalamin is the most stable and widely used form of vitamin B12, and has hematopoietic activity apparently identical to that of the antianemia factor in purified liver extract. Parenteral (intramuscular) administration of vitamin B12 completely reverses the megaloblastic anemia and GI symptoms of vitamin B12 deficiency.