Merivit Capsule

Uses

Merivit Capsule is also used to associated treatment for these conditions: Anaemia folate deficiency, Folate deficiency, Iron Deficiency (ID), Iron Deficiency Anemia (IDA), Latent Iron Deficiency, Neural Tube Defects (NTDs), Vitamin Deficiency, Methotrexate toxicity, Nutritional supplementationCandidiasis, Common Cold, Diaper Dermatitis, Diaper Rash, Eye redness, Iron Deficiency (ID), Ocular Irritation, Skin Irritation, Sunburn, Wilson's Disease, Zinc Deficiency, Dietary and Nutritional Therapies, Dietary supplementation

How Merivit Capsule works

Folic acid, as it is biochemically inactive, is converted to tetrahydrofolic acid and methyltetrahydrofolate by dihydrofolate reductase (DHFR). These folic acid congeners are transported across cells by receptor-mediated endocytosis where they are needed to maintain normal erythropoiesis, synthesize purine and thymidylate nucleic acids, interconvert amino acids, methylate tRNA, and generate and use formate. Using vitamin B12 as a cofactor, folic acid can normalize high homocysteine levels by remethylation of homocysteine to methionine via methionine synthetase.

Zinc has three primary biological roles: catalytic, structural, and regulatory. The catalytic and structural role of zinc is well established, and there are various noteworthy reviews on these functions. For example, zinc is a structural constituent in numerous proteins, inclusive of growth factors, cytokines, receptors, enzymes, and transcription factors for different cellular signaling pathways. It is implicated in numerous cellular processes as a cofactor for approximately 3000 human proteins including enzymes, nuclear factors, and hormones .

Zinc promotes resistance to epithelial apoptosis through cell protection (cytoprotection) against reactive oxygen species and bacterial toxins, likely through the antioxidant activity of the cysteine-rich metallothioneins .

In HL-60 cells (promyelocytic leukemia cell line), zinc enhances the up-regulation of A20 mRNA, which, via TRAF pathway, decreases NF-kappaB activation, leading to decreased gene expression and generation of tumor necrosis factor-alpha (TNF-alpha), IL-1beta, and IL-8 .

There are several mechanisms of action of zinc on acute diarrhea. Various mechanisms are specific to the gastrointestinal system: zinc restores mucosal barrier integrity and enterocyte brush-border enzyme activity, it promotes the production of antibodies and circulating lymphocytes against intestinal pathogens, and has a direct effect on ion channels, acting as a potassium channel blocker of adenosine 3-5-cyclic monophosphate-mediated chlorine secretion. Cochrane researchers examined the evidence available up to 30 September 2016 .

Zinc deficiency in humans decreases the activity of serum thymulin (a hormone of the thymus), which is necessary for the maturation of T-helper cells. T-helper 1 (Th(1)) cytokines are decreased but T-helper 2 (Th(2)) cytokines are not affected by zinc deficiency in humans [A342417].

The change of Th(1) to Th(2) function leads to cell-mediated immune dysfunction. Because IL-2 production (Th(1) cytokine) is decreased, this causes decreased activity of natural-killer-cell (NK cell) and T cytolytic cells, normally involved in killing viruses, bacteria, and malignant cells [A3424].

In humans, zinc deficiency may lead to the generation of new CD4+ T cells, produced in the thymus. In cell culture studies (HUT-78, a Th(0) human malignant lymphoblastoid cell line), as a result of zinc deficiency, nuclear factor-kappaB (NF-kappaB) activation, phosphorylation of IkappaB, and binding of NF-kappaB to DNA are decreased and this results in decreased Th(1) cytokine production .

In another study, zinc supplementation in human subjects suppressed the gene expression and production of pro-inflammatory cytokines and decreased oxidative stress markers [A3424]. In HL-60 cells (a human pro-myelocytic leukemia cell line), zinc deficiency increased the levels of TNF-alpha, IL-1beta, and IL-8 cytokines and mRNA. In such cells, zinc was found to induce A20, a zinc finger protein that inhibited NF-kappaB activation by the tumor necrosis factor receptor-associated factor pathway. This process decreased gene expression of pro-inflammatory cytokines and oxidative stress markers .

The exact mechanism of zinc in acne treatment is poorly understood. However, zinc is considered to act directly on microbial inflammatory equilibrium and facilitate antibiotic absorption when used in combination with other agents. Topical zinc alone as well as in combination with other agents may be efficacious because of its anti-inflammatory activity and ability to reduce P. acnes bacteria by the inhibition of P. acnes lipases and free fatty acid levels .

Dosage

Merivit Capsule dosage

May be taken with or without food.

Side Effects

Toxicity

IPR-MUS LD₅₀ 85 mg/kg,IVN-GPG LD₅₀ 120 mg/kg, IVN-MUS LD₅₀ 239 mg/kg, IVN-RAT LD₅₀ 500 mg/kg, IVN-RBT LD₅₀ 410 mg/kg

According to the Toxnet database of the U.S. National Library of Medicine, the oral LD50 for zinc is close to 3 g/kg body weight, more than 10-fold higher than cadmium and 50-fold higher than mercury .

The LD50 values of several zinc compounds (ranging from 186 to 623 mg zinc/kg/day) have been measured in rats and mice .

Precaution

Interaction

Volume of Distribution

Tetrahydrofolic acid derivatives are distributed to all body tissues but are stored primarily in the liver.

A pharmacokinetic study was done in rats to determine the distribution and other metabolic indexes of zinc in two particle sizes. It was found that zinc particles were mainly distributed to organs including the liver, lung, and kidney within 72 hours without any significant difference being found according to particle size or rat gender .

Elimination Route

Folic acid is absorbed rapidly from the small intestine, primarily from the proximal portion. Naturally occurring conjugated folates are reduced enzymatically to folic acid in the gastrointestinal tract prior to absorption. Folic acid appears in the plasma approximately 15 to 30 minutes after an oral dose; peak levels are generally reached within 1 hour.

Zinc is absorbed in the small intestine by a carrier-mediated mechanism . Under regular physiologic conditions, transport processes of uptake do not saturate. The exact amount of zinc absorbed is difficult to determine because zinc is secreted into the gut. Zinc administered in aqueous solutions to fasting subjects is absorbed quite efficiently (at a rate of 60-70%), however, absorption from solid diets is less efficient and varies greatly, dependent on zinc content and diet composition .

Generally, 33% is considered to be the average zinc absorption in humans . More recent studies have determined different absorption rates for various populations based on their type of diet and phytate to zinc molar ratio. Zinc absorption is concentration dependent and increases linearly with dietary zinc up to a maximum rate [L20902].

Additionally zinc status may influence zinc absorption. Zinc-deprived humans absorb this element with increased efficiency, whereas humans on a high-zinc diet show a reduced efficiency of absorption .

Half Life

The half-life of zinc in humans is approximately 280 days .

Clearance

In one study of healthy patients, the clearance of zinc was found to be 0.63 ± 0.39 μg/min .

Elimination Route

After a single oral dose of 100 mcg of folic acid in a limited number of normal adults, only a trace amount of the drug appeared in the urine. An oral dose of 5 mg in 1 study and a dose of 40 mcg/kg of body weight in another study resulted in approximately 50% of the dose appearing in the urine. After a single oral dose of 15 mg, up to 90% of the dose was recovered in the urine. A majority of the metabolic products appeared in the urine after 6 hours; excretion was generally complete within 24 hours. Small amounts of orally administered folic acid have also been recovered in the feces. Folic acid is also excreted in the milk of lactating mothers.

The excretion of zinc through gastrointestinal tract accounts for approximately one-half of all zinc eliminated from the body .

Considerable amounts of zinc are secreted through both biliary and intestinal secretions, however most is reabsorbed. This is an important process in the regulation of zinc balance. Other routes of zinc excretion include both urine and surface losses (sloughed skin, hair, sweat) .

Zinc has been shown to induce intestinal metallothionein, which combines zinc and copper in the intestine and prevents their serosal surface transfer. Intestinal cells are sloughed with approximately a 6-day turnover, and the metallothionein-bound copper and zinc are lost in the stool and are thus not absorbed .

Measurements in humans of endogenous intestinal zinc have primarily been made as fecal excretion; this suggests that the amounts excreted are responsive to zinc intake, absorbed zinc and physiologic need .

In one study, elimination kinetics in rats showed that a small amount of ZnO nanoparticles was excreted via the urine, however, most of the nanoparticles were excreted via the feces .

Pregnancy & Breastfeeding use

Contraindication

Acute Overdose

Storage Condition

Innovators Monograph

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