• Provision of written informed consent to participate in the study (according to Order of the Ministry of Health of Ukraine No. 690 (with amendments)).

• Female and male patients aged ≥18.

• Vitamin B12 deficiency, defined as serum vitamin B12 \< 350 pmol/L.

• Female patients of childbearing potential (WOCBP) must be using two acceptable methods of contraception, (e.g., intra-uterine device plus condom, spermicidal gel plus condom, diaphragm plus condom, etc., with the exception of oral contraceptives), from the time of screening and for the duration of the study, through study completion and for 1 month following study completion. Periodic abstinence (e.g., calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception. Postmenopausal females must have had no regular menstrual bleeding for at least one (1) year prior to initial dosing. Female patients who report surgical sterilization must have had the procedure at least six (6) months prior to initial dosing. Surgical sterilization procedures should be supported with clinical documentation made available to the sponsor and noted in the Relevant Medical History / Current Medical Conditions section of the CRF. All female patients of childbearing potential must have negative pregnancy test results at screening. An additional pregnancy test will be performed on Days 0, 28, 56.

• Able to communicate well with the investigator and able to understand and comply with the requirements of the study.

• Patients are otherwise in relatively good health as determined by past medical history, physical examination, vital signs, and laboratory tests at screening (V -1).