The whole problem is that in order for a substitution reaction to occur (whether it be S N 2 or acyl substitution) you need a decent leaving group
Lyanne Morrison, a functional medicine physician specialising in metabolic health and regenerative protocols, shared this perspective in a 2023 interview with the Journal of Anti-Aging Medicine : AOD 9064 represents one of the most exciting developments in precision peptide therapy

Indications and Usage for B!2 Inject Kit Cyanocobalamin is indicated for vitamin B 12 deficiencies due to malabsorption which may be associated with the following conditions: Addisonian (pernicious) anemia Gastrointestinal pathology, dysfunction, or surgery, including gluten enteropathy or sprue, small bowel bacteria overgrowth, total or partial gastrectomy Fish tapeworm infestation Malignancy of pancreas or bowel Folic acid deficiency It may be possible to treat the underlying disease by surgical correction of anatomic lesions leading to small bowel bacterial overgrowth, expulsion of fish tapeworm, discontinuation of drugs leading to vitamin malabsorption (see Drug Interactions), use of a gluten-free diet in nontropical sprue, or administration of antibiotics in tropical sprue
Park SH, Doh J, Park SI, Lim JY, Kim SM, Youn JI, et al