Oral administration of cyanocobalamin for functional vitamin В₁₂ deficiency: efficacy and safety

Abstract

The prevalence of vitamin В12 deficiency is about 3—16% in the general population, while in older people, it ranges from 10 to 20%. An increase in the proportion of people on reduced-calorie diets, the widespread use of drugs that can result in vitamin В12 deficiency, an increase in life expectancy, on the one hand, a variety of clinical manifestations and the lack of precise algorithms for laboratory diagnostics, on the other hand, suggest that the number of patients with vitamin В12 deficiency is significantly higher. Vitamin В12 can be absorbed by passive diffusion, regardless of intrinsic factor and other underlying causes of the deficiency. The presence of an additional route of absorption brings in new expectations for the oral administration of cyanocobalamin in therapeutic doses. Comparative clinical trials of the use of cyanocobalamin have shown that the oral route of administration is as effective as the parenteral. Considering the need for long-term, and in some cases — life-long, use of the drug, there is a need to develop dosage regimens for oral administration comparable in effectiveness to parenteral administration. The use of functional vitamin В12 deficiency biomarkers, such as vitamin В12 levels, cholotranscobalamin, methylmalonic acid, homocysteine, made it possible to establish that a daily dose of 1000 mkg is the most effective, which at the initial stage is as efficient as intramuscular administration. In some circumstances, maintenance therapy (intramuscularly at a dose of 1 mg/month) was more effective; thus, a differentiated approach scheme to determining the maintenance oral dose was proposed, depending on the result obtained at the initial stage of therapy. Comparative studies covering the entire spectrum from the recommended dietary allowance to the dose commonly used for cobalamin injections have shown that an oral daily dose of 1000 mcg of cyanocobalamin normalizes serum vitamin В12 levels and causes an 80—90% decrease in plasma methylmalonic acid concentration from the assumed maximum value. The oral route of administration provides a higher patient treatment adherence.

Keywords

• cyanocobalamin
• deficiency
• oral administration
• iatrogeny
• vitamin в₁₂
• holotranscobalamin
• methylmalonic acid