Effects of salt-type on drug effects?

[MyExcuse]

So recently I was reading about Morphine valerate which supposedly imbued morphine with an increased sedative action.

Ive also read reports on the use of Phenibut Citrate in Russia as an alternative to the hydrochloride, benefiting from a reduced sedation and increased anti-depressant action.

I was wondering if there was an easy way or documentation regarding the effects a salt will have on the activity of a drug?

 

[Solipsis]

IMO there is two separate issues to address with this question:

Firstly: the types of salt of a drug can have different physical properties that in the body can lead to slower or faster absorption. An example is Adderall which is pharmaceutical amphetamine and dextroamphetamine in mixed salt forms. Those different salts are meant to have slightly different kinetics I think, so different onset etc, which may 'soften' the total effect.
Also salts can vary in molecular weight, so even if they are just inactive/inert chaperones of the actual drug, they can be 'dead weight' that can affect potency. Hydrochloride is relatively light, so HCl salts are fairly potent.

Secondly: Salts are made up of a cation and anion (or a complex of several), so a positive and negatively charged. Usually the base is the drug, if the ionic acid portion is active itself! Such as in the case of valerate which is a form of valeric acid, then you have two drugs in one, bound together with ionic bond.

I'm racking my brain though why the phenibut citrate would be so different from hydrochloride, not only in kinetics but also pharmacodynamics? So even differering therapeutic action? Let me try to find something on that..

I think it's just the superior solubility > dissociation > absorption of the citrate - it very well must be since citrate from citric acid is not psychoactive. And it is cleaved from the phenibut almost as soon as it hits water.

http://www.ncbi.nlm.nih.gov/pubmed/22891435

But cannot read the full article

 

[belligerent drunk]

Isn't valeric acid one of the psychoactives in valerian root? That would explain the increased sedation IMO.

Also, as Solipsis said, I see no reason for phenibut to have different pharmacodynamics based on the counter-ion. I can't find the full text for that article either. The only difference would be if citric acid would somehow non-covalently bind to phenibut while in the stomach and by that increase its speed of absorption. As soon as it entered bloodstream, though, they would indeed part ways as far as I can tell.

 

[dopemaster]

I wondered this too.

I have been on and off of morphine sulphate for the last 6 or 7 years for chronic pain. Is there a rx for morphine hcl or is it how I figured with morphine sulphate being what was in most morphine pills?

 

[bingey]

salt form matters a lot to IV users but that's usually due to low water solubility of some Salts like sulphates