Each New Year, millions of people set resolutions to lose weight, typically through a combination of diet and exercise. Many people often choose to supplement this approach with weight loss medications and supplements, such as vitamin B12. Since the 1950s, many studies have shown that vitamin B12 plays a role in the metabolism of lipids and carbohydrates and serves as an energy source for various biological processes. If your patients are having difficulty losing weight or if vitamin B12 absorption is problematic, intramuscular injections containing vitamin B12 may help due to their higher bioavailability compared with oral administration. This is particularly important for patients that elect for weight loss surgery, many of whom subsequently suffer from vitamin B12 malabsorption.1
Although they won’t cause your patients to lose weight overnight, vitamin B12 injections can be a critical part of weight loss and management plans. The injections can provide a variety of benefits to patients, including sustained energy levels and improving the symptoms associated with other weight loss medications, like WegovyⓇ. Before prescribing vitamin B12, prescribers should be aware of its different forms and how they may help maximize weight loss or decrease the side effects of taking other weight loss medications.
Which form of vitamin B12 should be prescribed?
Although often used as a catchall term, there are actually several different forms of vitamin B12 depending on subtle differences in their chemical structures. Most precisely, vitamin B12 is the cobalamin molecule, which can have various other groups attached, giving the resulting analogs different functions in the human body. Methylcobalamin, adenosylcobalamin, and hydroxocobalamin are naturally-occurring forms of vitamin B12, while cyanocobalamin is synthetic. A highly simplified metabolic cycle of the different forms of the vitamin is shown below to illustrate how interrelated these different forms are.2
Cyanocobalamin is the synthetic analog of vitamin B12 that was developed to increase the shelf-life of vitamin B12, as the two naturally-occurring forms undergo photolytic degradation. In the serum, it is converted into hydroxocobalamin and then into the two active forms of B12, methylcobalamin and adenosylcobalamin. Since it is metabolized into both forms of B12, a cyanocobalamin injection provides the body with both forms, making it more suitable when the body has a deficiency of both. Because cyanocobalamin must be converted into either methylcobalamin or adenosylcobalamin, this extra step can slightly delay the conversion into the two active forms of the vitamin.
Similar to cyanocobalamin, hydroxocobalamin is converted into the two active forms of vitamin b12. Hydroxocobalamin is a natural form of vitamin B12 and is only available via prescription injection, which must be performed by a medical professional. In contrast to other forms, it usually requires a diagnosis of a vitamin B12 deficiency or cyanide poisoning. This form is converted into the two other naturally-occurring forms of vitamin B12, methylcobalamin and adenosylcobalamin. Compared with cyanocobalamin, hydroxocobalamin stays in circulation longer, allowing for longer intervals between injections.
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Methylcobalamin and Adenosylcobalamin
Methylcobalamin is one of the two active forms of vitamin B12 and helps animals use CO2 as their carbon source to produce acetyl-CoA, and it also has a higher retention rate than other forms. Adenosylcobalamin is the other active form of vitamin B12 that participates in carbohydrate, fat, and amino acid metabolism. If a patient has a deficiency of only one of these two forms of vitamin B12, an injection containing only one of these forms may be necessary. However, research has shown that both forms should generally be administered if a patient is suffering from deficiency.2
Combinations of vitamin B12 with other drugs to maximize benefits
Even if another medication is ultimately the correct choice for your patient, vitamin B12 injections may still provide additional benefits when combined with other weight loss medications, either by working synergistically with them or by helping reduce side effects.
Metformin is FDA-approved to treat hyperglycemia in patients with type 2 diabetes. Although not FDA-approved for weight loss, metformin is a common off-label prescription for weight loss because several studies have shown a link between its prescription and weight loss and a reduction in appetite. However, metformin is known to block the absorption of vitamin B12 levels in patients, posing a potentially severe risk of additional nerve damage in patients with type 2 diabetes.3 Vitamin B12 injections can be administered to help overcome this deficiency.
Novo Nordisk’s blockbuster incretin, WegovyⓇ (semaglutide), has been so popular that the manufacturer has struggled to meet demand. This has led to questionable practices, including the use of compounded semaglutide sodium and the off-label prescription of the diabetes medication OzempicⓇ, which also uses semaglutide as the API. Due to explosive demand, Novo Nordisk faced supply issues and repeatedly pushed back the expected availability date of WegovyⓇ, only very recently announcing its re-availability in December 2022. Even if patients insist on being prescribed WegovyⓇ, vitamin B12 can still be prescribed, as research has suggested it may help tolerate the nausea and vomiting that are common with GLP-1 agonists.4
All three injections contain somewhat similar blends of ingredients including methionine, inositol and choline (MIC). These injections are intended to accelerate metabolism as well as suppress appetite. Vitamin B12 can be combined with the MIC cocktail (i.e., lipotropic injections) to maximize benefits by providing an additional energy boost. With regular injections, these formulations may be a great way to help patients increase their lipid metabolism and assist with maintaining or achieving high energy levels as part of a healthy diet and exercise regimen.
Why choose VLS Pharmacy and New Drug Loft?
From increasing tolerance to other weight loss medications to potentially helping patients lose weight when combined with other medications, vitamin B12 presents a promising option in your patients’ journeys to reach their weight loss goals. Regardless of which form of the injection you prescribe, VLS Pharmacy will tailor the injection’s formulation to meet each individual’s specific needs. As a 503A pharmacy specializing in sterile and non-sterile compounding, we will support you and your patients by creating safe, individualized, and effective pharmaceutical therapies. All formulations are compounded with high-quality pharmaceutical-grade APIs sourced directly from PCCA, the leader of superior-quality APIs.
For men and women at any age, feeling healthy, conﬁdent, and comfortable is of the utmost importance. Your patients’ needs will change with each life stage. As such, they require an adaptive and personalized treatment plan. By working with a trusted compounding pharmacy like VLS Pharmacy and New Drug Loft, you are expanding the possibilities for successful and sustainable care.
Reach out to our team to learn about best practices and to partner with our experts on custom compounded medications for your patients. All medications from VLS Pharmacy and New Drug Loft are prepared in a lab that follows safety and quality standards per our status as a 503A pharmacy.
- Lombardo M, Franchi A, Rinaldi RB, et al. Long-Term Iron and Vitamin B12 Deficiency Are Present after Bariatric Surgery, despite the Widespread Use of Supplements. Public Health. 2021;18:4541. doi:10.3390/ijerph18094541
- Thakkar K, Billa G. Treatment of vitamin B12 deficiency-methylcobalamine? Cyancobalamine? Hydroxocobalamin?-clearing the confusion. Eur J Clin Nutr. 2015;69(1):1-2. doi:10.1038/EJCN.2014.165
- Kim J, Ahn CW, Fang S, Lee HS, Park JS. Association between metformin dose and vitamin B12 deficiency in patients with type 2 diabetes. Medicine (Baltimore). 2019;98(46):e17918. doi:10.1097/MD.0000000000017918
- Mietlicki-Baase EG, Liberini CG, Workinger JL, et al. A vitamin B12 conjugate of exendin-4 improves glucose tolerance without associated nausea or hypophagia in rodents. Diabetes, Obes Metab. 2018;20(5):1223-1234. doi:10.1111/DOM.13222
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