hydroxyzine salt

[n0mad]

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hi, can someone explain to me the difference between
the two salt forms for hydroxyzine? how does hcl and
pamoate differs in absorption? i mean how does the chemical
process makes hcl different from pamoate?

its not for a school project or anything.. im just clueless
in this matter.. like sevelamer hcl versus carbonate? i wanna
know why they have two salt forms for a drug..

 

[n0mad]

i tried asking two pharmacists without luck..
i'll ask the owner/pharmacist when he has time..
but i dont think he knows about it either..

 

[shal]

Here is a comment made by an RPh on pharmacist's letter:

"The pamoate salt is indeed (by my understanding) a better choice for anxiety due to its higher ability to enter the brain (by crossing the blood-brain-barrier) whereas the HCL form is a better choice to avoid CNS effects due to its lower ability to enter the brain. Although plausable, this is arguement is, to my knowledge, all theorectical as I have not seen any studies prove (or even test) this assumption. However, this logic can likely be claimed as reasoning to prefer one salt over the other. A simple bioavailability test would not show this difference, and the involved / expensive tests required to test this theory are unlikely to be undertaken since there would be little, if any, means of recoping the cost. In short, don't expect a definative answer to this question any time soon"

 

[Express08]

The only difference is solubility.

HCl is freely soluble in water & alcholol therefore it is available as the injectable as well as the oral formulation.

The pamoate salt is insoluble in water or alcohol so is not available as an injectable formulation

They both dissociate completely in the gut so they are equivalent in equivalent therapeutic doses (the strengths differ due to the salt mass). It is only the dissociated drug which crosses the blood brain barrier & even that is not an issue normally since it is often used for uticaria - thus peripheral tissues.

Simple - it has to do only with marketing and who it is marketed to, altho it is such an old drug, that is no longer an issue.

Therapeutically, you can interchange salts, depending on your state of practice.

 

[n0mad]

thanks everyone for an awesome response..

 

[DrugDealer]

like sevelamer hcl versus carbonate? i wanna
know why they have two salt forms for a drug..

The sevelamer component is not meant to be absorbed...it stays in the gut to bind up phosphates. But, I think maybe some patients were absorbing the HCl component and developing acidodis, so I think the carbonate salt is meant to avoid that issue. I don't think there are any trials to show this benefit, it is just theoretical at this point.