D-Panthenol 50 mg, Methylcobalamin 1500 mcg, Nicotinamide 100 mg, Pyridoxine 100 mg, Thiamine 100 mg / 2 ml Liquid injectables

Mecobalamin is a coenzyme form of vitamin B12 that participates in methionine-synthase-mediated transfer of methyl groups during conversion of homocysteine to methionine. The reference separates this biochemical role from experimental nerve-cell and animal findings.

In twelve healthy men given 500 micrograms, total serum B12 peaked at approximately 0.9 hours after intramuscular administration and immediately to 3 minutes after intravenous administration. The reported half-lives were 29.0 and 27.1 hours respectively. These measurements concern total serum B12 after accounting for endogenous concentrations, not a selective assay of unchanged methylcobalamin. They do not establish the kinetics of a 1,500- or 2,500-microgram combination product.

Nicotinamide contributes to NAD and NADP coenzymes involved in cellular oxidation-reduction reactions.

The intravenous multivitamin reference describes plasma vitamin B3 in acid or amide forms and urinary elimination as unchanged substance or metabolites. It does not provide a nicotinamide-specific half-life or validate another injection mixture.

The reference supplies vitamin B5 as dexpanthenol. Pantothenic acid is a precursor of coenzyme A in carbohydrate and lipid metabolism.

The intravenous reference describes vitamin B5 in plasma and red cells as free pantothenic acid or coenzyme A, with urinary elimination. These are vitamin disposition data, not a measured unchanged-dexpanthenol half-life or evidence for intramuscular kinetics.

The water soluble vitamins are widely distributed in both plants and animals. They are absorbed in man by both diffusion and active transport mechanisms. These vitamins are structurally diverse (derivatives of sugar, pyridine, purines, pyrimidine, organic acid complexes and nucleotide complex) and act as coenzymes, as oxidation-reduction agents, possibly as mitochondrial agents. Metabolism is rapid, and the excess is excreted in the urine.

Thiamine is distributed in all tissues. The highest concentrations occur in liver, brain, kidney and heart. When thiamine intake is greatly in excess of need, tissue stores increase two to three times. If intake is insufficient, tissues become depleted of their vitamin content. Absorption of thiamine following IM administration is rapid and complete.

Thiamine combines with adenosine triphosphate (ATP) to form thiamine pyrophosphate, also known as cocarboxylase, a coenzyme. Its role in carbohydrate metabolism is the decarboxylation of pyruvic acid in the blood and α-ketoacids to acetaldehyde and carbon dioxide. Increased levels of pyruvic acid in the blood indicate vitamin B1 deficiency.

The requirement for thiamine is greater when the carbohydrate content of the diet is raised. Body depletion of vitamin B1 can occur after approximately three weeks of total absence of thiamine in the diet.

Natural substances that have vitamin B 6 activity are pyridoxine in plants and pyridoxal or pyridoxamine in animals. All 3 are converted to pyridoxal phosphate by the enzyme pyridoxal kinase. The physiologically active forms of vitamin B 6 are pyridoxal phosphate (codecarboxylase) and pyridoxamine phosphate. Riboflavin is required for the conversion of pyridoxine phosphate to pyridoxal phosphate.

Vitamin B 6 acts as a coenzyme in the metabolism of protein, carbohydrate, and fat. In protein metabolism, it participates in the decarboxylation of amino acids, conversion of tryptophan to niacin or to serotonin (5-hydroxtryptamine), deamination, and transamination and transulfuration of amino acids. In carbohydrate metabolism, it is responsible for the breakdown of glycogen to glucose-1-phosphate.

The total adult body pool consists of 16 to 25 mg of pyridoxine. Its half-life appears to be 15 to 20 days. Vitamin B 6 is degraded to 4-pyridoxic acid in the liver. This metabolite is excreted in the urine.

The need for pyridoxine increases with the amount of protein in the diet. The tryptophan load test appears to uncover early vitamin B 6 deficiency by detecting xanthinurea. The average adult minimum daily requirement is about 1.25 mg. The ‘‘Recommended Dietary Allowance’’ of the National Academy of Sciences is estimated to be as much as 2.2 mg for adults and 2.5 mg for pregnant and lactating women. The requirements are more in persons having certain genetic defects or those being treated with isonicotinic acid hydrazide (INHJ) or oral contraceptives.