for those with neurological involvement, 1 mg on alternate days until no further improvement
This timeline matches B12 pharmacokinetics: intramuscular methylcobalamin reaches peak serum concentration at 8-12 hours, but tissue saturation (particularly in the liver and nervous system) occurs over 48-72 hours as the vitamin is transported into cells and converted to active coenzyme forms (Andrs et al., 2018)
Pernicious anemia occurs more commonly in people who already have diseases that are linked to immune-system abnormalities, such as Graves disease, hypothyroidism (under-functioning thyroid gland), thyroiditis (inflammation of the thyroid), vitiligo, and Addison's disease (adrenocortical insufficiency)
MHRA-approved options include orlistat (prescription and over the counter), semaglutide (Wegovy, supported by NICE TA875), and liraglutide (Saxenda, supported by NICE TA664)