Pernicious Anaemia Society
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Difference between Neo-Cytamen Hydroxocobalamin Chloride and Mercury pharma Hydroxocobalamin Acetate


Went to collect my B12 ampoules from chemist this afternoon and realised instead of being given my usual brand Neo-Cytamen they have given me the Mercury Pharma brand.

The former contains hydroxocobalamin Chloride 1000 microgram/ml and the latter Hydroxocobalamin Acetate 1mg/ml. On the information leaflet of the acetate it states: This injection contains less than 1 mmol (23mg) of sodium per 2ml (essentially "sodium free"). What does that mean exactly? On the box ingredients listed are: hydroxocobalamin equivalent to 1mg hydroxocobalamin. Also contains acetic acid and sodium chloride in water for injections.

The Neo-Cytamin contains 1027 micrograms of Hydroxocobalamin chloride/ml (equivalent to 1000 micrograms of hydroxocobalamin/ml). Also contains glacial acetic acid (E260), sodium chloride, water. What is the difference between "glacial" acetic acid and plain acetic acid?

So am wondering if the B12 from Mercury Pharma is as potent as the one from Neo-Cytamen? Would be interested to hear from anyone who has used the Mercury Pharma after using the Neo-Cytamen brand: Have you found any difference at all?

Which is the best?

Thanks for commenting.

11 Replies

They are, essentially, identical.

The hydroxocobalamin chloride will dissociate into hydroxocobalamin and chloride ions when it dissolves. The acetic acid (glacial acetic acid is just more concentrated, it's irrelevant once it's in water) will produce acetate ions and hydrogen ions. The sodium chloride will produce sodium and chloride ions.

So the solution will contain hydroxocobalamin, sodium ions, chloride ions, hydrogen ions and acetate ions.

The hydroxocobalamin acetate will dissociate into hydroxocobalamin and acetate ions. Acetic acid and sodium chloride will behave as before,

So the solution will contain hydroxocobalamin, sodium ions, chloride ions, hydrogen ions and acetate ions.

Both end up containing the same amount of hydroxocobalamin and roughly the same amount of other ions.


So I should not notice any difference at all? Thanks fbirder for prompt reply.


Wow, you're good!!!! 😁


Thanks ☺️

It's fairly basic chemistry - but only if you've studied it.


True fbirder... have only studied chemistry to A level, many decades ago... I understand you studied it at degree level and appreciate your concise explanations. Thanks again.

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I was started on Cytamen (cyanocobamalin) every 4 weeks 45 years ago and then sometime during the 1980s Neo-Cytamen (Hydroxocobamalin) was introduced allegedly because P.A. sufferers would then only need to have their injections every three months.

Sadly I had an adverse reaction to the Neo-Cytamen and certainly couldn't last the three months so i have continued on the old Cytamen ever since and now have it injected every three weeks - at the age of 75.

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Thanks for your response Clive. I have been having Neo-Cytamen since I stated the injections in February and was a little dismayed to see the chemist gave me a different brand and just wanted to make sure the Mercury Pharma hydroxocobalamin would be just as efficient as that of Neo-Cytamen.


Hi, I have just questioned my pharmacy if ther is a difference depending which brand I get as I have for 10 years used a brand with neo in the title not really taking notice just asking for B12 injections and occasional being given the generic brand I believed I would feel different in my six week period before next injection being my symptoms were worse. I was told both brands we're identical but I believe I do feel different dependent on brand I am relieved to read I'm not alone. Thanks



Some people say there is no difference... Just as chemists will say so, but they say that about any generic that costs less. However, I now think there is a difference. Some people may not feel it and others will. We are all different and react differently to chemicals, etc.

Although they are supposed to be exactly the same _ same chemical formula _ they don't seem to give me the same benefical therapy. It does sound illogical but I do know my body and how it reacts to various treatments. It is the same with biosimilars of biologic injections used to help with RA. I know the brand that gives me the best therapy, I can assure you. Furthermore it is not all in my mind.... as some people might think. Interesting you have felt the difference too. Thank you for letting me know.

Which brand is best for you? Are you in the UK?

I will say that a six week interval between injections might be too long to help you feel better. I inject more often. Each time I have tried to reduce the number of injections my symptoms come back very quickly. This must indicate that injections are required closer together, but there again it depends on each individual and the extent of the symptoms as well as the time span before treatment started. I am not medically qualified, just someone who has had to fight in order to obtain B12, like many other people.


Hi, I am from Australia and luckily we can get injections over the counter without a script and I am able to get my injections as often as I need I can not imagine what it must be like in the Uk or other places to not have this available I know I'm truly blessed in that regard. I can't believe what I have been reading. But still not a lot is know here either and I was led to believe that once treated with B12 you are fine and live normally . I have be trying to get my injection time reviewed but my blood test show my b12 levels are high so I thought I couldn't possibly have more. I was recently diagnosed with IBS (irritable bowl syndrome) but I'm starting to believe my symptoms are tied to my PA ?? I don't know?? I'm now more confident now to not accept all that the blood test show. But It has been to coincidental I have felt worse with the generic brand (hydroxocobamalin as chloride) as a pose to the neo-hydroxocobamalin I think that is what it's called not having the box I'm not sure of it exact name. Just knowing I'm not alone in how I feel is reassuring.:)


Surely you must have done some research regarding B12 and once one begins injecting B12 it is not necessary to have blood test for B12 because the level will be very high, which is normal. B12 is water soluble therefore any excess will be excreted via urine.There are many posts on this forum so please read them and learn from all the useful information. We are all different and you need to see how well your symptoms are improving and be guided by that.

I am not a medically qualified person, just someone who is trying to improve my health issues.


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