According to British Society for Haematology (BSH) guidelines and NICE Clinical Knowledge Summaries (CKS), the primary beneficiaries include: Key patient groups who may require B12 injections include: Pernicious anaemia patients requiring lifelong hydroxocobalamin 1mg intramuscularly every 23 months following initial loading doses Patients with gastrointestinal disorders including those who have undergone gastrectomy or ileal resection, and patients with conditions affecting B12 absorption such as Crohn's disease or coeliac disease Strict vegans and vegetarians though oral supplementation is usually sufficient unless malabsorption is present Elderly patients who may have reduced gastric acid production affecting B12 absorption Patients taking certain medications including metformin (MHRA advises monitoring B12 levels in long-term users, particularly those with risk factors or symptoms), proton pump inhibitors, and H2-receptor antagonists long-term [6] Individuals with neurological symptoms such as paraesthesia, ataxia, or cognitive impairment related to B12 deficiency Pregnant women with confirmed deficiency (hydroxocobalamin for malabsorption

Do not double the dose to catch up
Refills Health is one platform operating in this space
USA 103, 1464714648 (2006)
Compounding pharmacies are required to use the active ingredients of a drug being replicated and are subject to oversight by their respective state board of pharmacy and/or FDA
Tirzepatide (brand names Mounjaro and Zepbound) was only approved last year, so its patent has many more years