Some researchers question whether these non-cyanocobalamin supplements are
stable in their oral form. For this reason, much larger amounts are typically
used with hope that at least some are absorbed intact. One study suggests that
once absorbed, methylcobalamin may be retained in the body better than
cyanocobalamin.30
…
The advantage using hydroxocobalamin is the lack of adverse effects seen with
the nitrites such as methemoglobinemia and hypotension. It works by exchanging
the hydroxy group for cyanide to form the non-toxic cyanocobalamin (vitamin
B12). …
The hydroxocobalamin neutralizes cyanide by fixing it to form cyanocobalamin
(vitamin B12) which is excreted in the urine. It does not have the problem of
reducing the blood’s capacity to carry oxygen as in the case of nitrite
administration. Hydroxocobalamin is red in color and will turn the mucous
membranes, skin, and urine red, which could interfere with clinical laboratory
tests which depend on color. …
The antitode used in Europe is hydroxocobalamin, a precursor to Vitamin B-12.
The drug is given intravenously and neutralizes cyanide to form cyanocobalamin,
Vitamin B-12, which the body expells by urination. …