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Methylcobalamin Injection (Methycobal 500 Injection)
500 mcg/mL Solution for Injection (IM/IV)
Each mL contains:
Methycobal ……………………500 mcg
Each mL contains:
Methycobal ……………………500 mcg
- Specification : 1ml:0.5mg
- DOSAGE FORM : Injection
- Product Details
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methylcobalamin Injection/ Methycobal Injection / mecobalamin injectionPHARMACOKINETICS:
Vitamin BI2 substances bind to intrinsic factor, a glycoprotein secreted by the gastric mucosa, and are then actively absorbed from the gastrointestinal tract. Absorption is impaired in patients with an absence of intrinsic victor, with a malabsorption syndrome or with disease or abnormality of the gut, or after gastrectomy. Absorption from the gastrointestinal tract can also occur by passive diffusion; little of the vitamin present in food is absorbed in this manner although the process becomes increasingly important with larger amounts such as those used therapeutically. After intranasal dosage, peak plasma concentrations of cyanocobalamin have been reached in l to 2 hours. The bioavailability of the intranasal preparation is about 7 to 11% of that by intramuscular injection.
Vitamin B12 is extensively bound to specific plasma proteins called transcobalamins; transcobalamin II appears to he involved in the rapid transport of the cobalamins to tissues. Vitamin B12 is stored in the liver, excreted in the bile, and undergoes extensive enterohepatic recycling; part of a dose is excreted in the urine, most of it in the first 8 hours; urinary excretion, however, accounts for only a small fraction in the reduction of total body stores acquired by dietary means. Vitamin B12 diffuses across the placenta and also appears in breast milk.
Vitamin B12, a water-soluble vitamin, occurs in the body mainly as methylcobalamin (mecobalamin) and as adenosylcobalamin (cobamamide) and hydroxocobalamin. Mecobalamin and cobamamide act as coenzymes in nucleic acid synthesis. Mecobalamin is also closely involved with folic acid in several important metabolic pathways.
Vitamin B12 deficiency can occur in strict vegetarians with an inadequate dietary intake, although it may take many years before a deficiency is produced. Deficiency is more likely in patients with malabsorption syndromes or metabolic disorders, nitrous oxide-induced megaloblastosis, or after gastrectomy or extensive ileal resection. Deficiency leads to the development of megaloblastic anaemias and demyelination and other neurological damage. A specific anaemia known as pernicious anaemia develops in patients with an absence of the intrinsic factor necessary for good absorption of the vitamin from dietary sources.
Vitamin B12 preparations are used in the treatment and prevention of vitamin B12 deficiency. It is essential to identify the exact cause of deficiency, preferably before starting therapy. Hydroxocobalamin is generally preferred to cyanocobalamin; it binds more firmly to plasma proteins and is retained in the body longer. Cyanocobalamin and hydroxocobalamin are generally given by the intramuscular route, although cyanocobalamin may be given by mouth or intranasally. Oral cyanocobalamin may be used in treating or preventing vitamin B12 deficiency of dietary origin.
DOSAGE AND ADMINISTRATION:
Mecobalamin recommended doses for pernicious anaemia and other macrocytic anaemias without neurological involvement are hydroxocobalamin (or cyanocobalamin) 250 to 1000 micrograms intramuscularly on alternate days for 1 to 2 weeks, then 250 micrograms weekly until the blood count returns to normal. Maintenance doses of 1000 micrograms of hydroxocobalamin are given every 2 to 3 month (or monthly for cyanocobalamin). If there is neurological involvement, hydroxocobalamin or cyanocobalamin may be given in doses of 1000 micrograms on alternate days and continued for as long as improvement occurs. For the prophylaxis of anaemia associated with vitamin B12, deficiency resulting from gastrectomy or malabsorption syndromes hydroxocobalamin may be given in doses of 1000 micrograms intramuscularly every 2 or 3 months or cyanocobalamin in doses of 250 to 1000 micrograms intramuscularly each month. For vitamin B12 deficiency of dietary origin, cyanocobalamin 50 to 150 micrograms may be taken daily by mouth between meals.
Lower doses of both cyanocobalamin and hydroxocobalamin are recommended in the USA. For the treatment of deficiency, the usual intramuscular dose of cyanocobalamin is 100 micrograms daily for 7 days, then on alternate days for 7 further doses, then every 3 to 4 days for 2 to 3 weeks. For hydroxocobalamin the dose is 30 to 50 micrograms daily for 5 to 10 days. For maintenance, both cyanocobalamin and hydroxocobalamin are given at a dose of 100 to 200 micrograms monthly, based on haematological monitoring. An intranasal preparation of cyanocobalamin is also available for maintenance therapy, the recommended dose being 500 micrograms once weekly. Oral doses of up to 1000 micrograms of cyanocobalamin have also been used. In patients with normal gastrointestinal absorption, doses of 1 to 25 micrograms daily are considered sufficient as a dietary supplement.
Treatment usually results in rapid haematological improvement and a striking clinical response. However, neurological symptoms respond more slowly and in some cases remission may not be complete.
1-lydroxocobalamin may also be given in the treatment of tobacco amblyopia and Leber's optic atrophy; initial doses are 1000 micrograms daily for 2 weeks intramuscularly followed by 1000 micrograms twice weekly for as long as improvement occurs. Thereafter, 1000 micrograms is given every 1 to 3 months.
Cyanocobalamin and hydroxocobalamin are also used in the Schilling test to investigate vitamin B12 absorption and deficiency states. They are given in a nonradioactive form together with cyanocobalamin radioactively-labelled with cobalt-57or cobalt-58 and the amount of radioactivity excreted in the urine can be used to assess absorption status. A differential Schilling test, in which the forms of cyanocobalamin are given under different conditions can provide information concerning the cause of the malabsorption. Cobamamide and mecobalamin may also be used for vitamin B12 deficiency.
Allergic hypersensitivity reactions have occurred rarely after parenteral doses of the vitamin B12 compounds cyanocobalamin and hydroxocobalamin. Antibodies to hydroxocobalamin-transcobalamin II complex have developed during hydroxocobalamin therapy.
Arrhythmias secondary to hypokalaemia have occurred at the beginning of parenteral treatment with hydroxocobalamin.
Intranasal cyanocobalamin may cause rhinitis, nausea, and headache.
Cyanocobalamin or hydroxocobalamin should, if possible, not be given to patients with suspected vitamin B12 deficiency without first confirming the diagnosis. Regular monitoring of the blood is advisable. Use of doses greater than 10 micrograms daily may produce a haematological response in patients with folate deficiency; indiscriminate use may mask the precise diagnosis. Conversely, folate may mask vitamin B12 deficiency.
Cyanocobalamin should not be used for Leber's disease or tobacco amblyopia since these optic neuropathies may degenerate further.
FOODS, DRUGS, DEVICES and COSMETICS ACT prohibits dispensing without prescription.
Store at temperatures not exceeding 30ºC.
10 amber ampoules x 500 mcg/mL (Box of 10’s)
Methylcobalamin Suppliers & Manufacturer:
JIANGSU SIHUAN BIOENGINEERING CO., LTD.
No. 10, Dingshan Road Binjiang Development Zone,
Jiangyin, Jiangsu, CHINA