Difference between Quetiapine Fumarate and Hemifumarate

[crubsc]

Hey everyone!

Is there a difference between Quetiapine Fumarate and Quetiapine Hemifumarate? Here in Brazil, Seroquel is sold under the substance name of "Quetiapine Fumarate" but the generic Quetiapines sold are all "Quetiapine Hemifumarate". I'm curious about it and would appreciate any answer to clarify this difference (if there is one).

Thanks in advance!

 

[sekio]

They should be the same thing. Fumaric acid is a diprotic acid so binds two quetiapine molecules. Hence for every quetiapine molecule there is "1/2" a fumaric acid molecule, ergo "hemifumarate".

If it was a 1:1 ratio it would be quetiapine bifumarate.

 

[crubsc]

Thanks for your answer sekio! I'm not sure though that I understand what you said. One quetiapine fumarate has two quetiapine hemifumarate molecules? Since all the generics here are Quetiapine Hemifumarate, I don't think that being a hemifumarate would affect the dosage as compared to the fumarate... What else can you tell me? I'm not a pharmacology expert, so if you could explain in a more simple way I'd very much appreciate it.

Best greetings!!

 

[crubsc]

I found this article (in Portuguese) which has a very good explanation about the difference between Fumarate and Hemifumarate in general (not specifically about Quetiapine). I'll post the google translation below, trying to make some improvements on the translation (even if my English is not that good):

"I- Fumarate is But-2-em-1,4-dioic acid and is a precursor of malate in the Krebs Cycle, at the end of the biochemical process in the human body.

Hemifumarate, though, always appears in the middle of chemical processes to obtain drugs (medicines). I believe it should exhibit a behavior similar to that of fumarate in the body and its biochemical processes, but while fumarate is natural, hemifumarate is synthetic. I believe this is why it is a molecule used as a mean to carry substances througout the body to treat diseases ranging from high blood pressure to depression.


- Both molecules have a high acid / base characteristics (although hemifumarate is much more basic due to the presence of amine / amide groups, which are not found in the simple structure of the fumarate, which still presents two COOHs (acid groups) as more polar groups therefore having a very acid character)."

 

[S.J.B.]

Thanks for your answer sekio! I'm not sure though that I understand what you said. One quetiapine fumarate has two quetiapine hemifumarate molecules? Since all the generics here are Quetiapine Hemifumarate, I don't think that being a hemifumarate would affect the dosage as compared to the fumarate... What else can you tell me? I'm not a pharmacology expert, so if you could explain in a more simple way I'd very much appreciate it.

I found this article (in Portuguese) which has a very good explanation about the difference between Fumarate and Hemifumarate in general (not specifically about Quetiapine). I'll post the google translation below, trying to make some improvements on the translation (even if my English is not that good):

"I- Fumarate is But-2-em-1,4-dioic acid and is a precursor of malate in the Krebs Cycle, at the end of the biochemical process in the human body.

Hemifumarate, though, always appears in the middle of chemical processes to obtain drugs (medicines). I believe it should exhibit a behavior similar to that of fumarate in the body and its biochemical processes, but while fumarate is natural, hemifumarate is synthetic. I believe this is why it is a molecule used as a mean to carry substances througout the body to treat diseases ranging from high blood pressure to depression.


- Both molecules have a high acid / base characteristics (although hemifumarate is much more basic due to the presence of amine / amide groups, which are not found in the simple structure of the fumarate, which still presents two COOHs (acid groups) as more polar groups therefore having a very acid character)."

What Sekio meant is that "quetiapine fumarate" and "quetiapine hemifumarate" are two names for the exact same thing. "Hemifumarate" is just a more specific description of the salt present in the drug, the "hemi-" being there to specify the ratio of fumaric acid (1) to quetiapine (2). If the label says "quetiapine fumarate" it will have the exact same ratio. It has nothing to do with a natural source vs. a synthetic source.

 

[crubsc]

What Sekio meant is that "quetiapine fumarate" and "quetiapine hemifumarate" are two names for the exact same thing. "Hemifumarate" is just a more specific description of the salt present in the drug, the "hemi-" being there to specify the ratio of fumaric acid (1) to quetiapine (2). If the label says "quetiapine fumarate" it will have the exact same ratio. It has nothing to do with a natural source vs. a synthetic source.

Thanks for your nice answer and for sharing your knowledge. I guess I understand now the difference between a fumarate and a hemifumarate, so basically: 1) it has more to do with specifying the salt presented in the drug and 2) the ratio of fumaric acid to quetiapine 1:2.

Best wishes!