Studies on a Long-acting Vitamin B12Preparation

Abstract

Vitamin B₁₂ was converted to an insoluble zinc tannate complex. Subcutaneous injection in rats caused continuous absorption and urinary excretion of vitamin B₁₂ for two weeks from a single dose equivalent to 500 µg vitamin B₁₂. A similar dose injected intramuscularly in humans showed urinary excretion of less than 2 per cent of the injected dose. Serum level vitamin B₁₂ was promptly elevated by several times that of control values, and these levels (above control value) were sustained for 28 days or more from the single dose. Certain implications of these findings are discussed in relation to previous concepts of vitamin B₁₂ therapy. The increased capacity of CZT injection to provide “body pool” vitamin B₁₂ repletion and long-sustained elevated vitamin B₁₂ serum levels makes it possible to study vitamin B₁₂ therapy of a type not attainable with previous preparations of the vitamin, oral or parenteral. Clinical indications and areas for studying the therapeutic potential of CZT are cited.