Hello,

I can not answer for the lop P and log D, but the pKa is a physicochemical property independant of the acidic form.

Thehydrochloride form is just the protonated form of the molecule, here a protonated nitrogen atom.

For the log P , as it is a solubility difference between octanol and water, it is influenced by the acido basic form.

Dear Rene,

Solubility of HCl (or other) salts of drugs differs from their base compounds. So, it is better to check their published experimental data. Please see below where you can find some experimental data on Lidocaine and its hydrochloride salt.

Lidocaine:

logP: Wassvik, Carola M.; Journal of Medicinal Chemistry 2008, V51(10), P3035-3039. logD & Solubility: Kokate, Amit; Pharmaceutical Research 2009, V26(5), P1130-1139.

Acid/Base Dissociation Constant (Ka/Kb): Luan, Feng; Pharmaceutical Research 2005, V22(9), P1454-1460.

Lidocaine hydrochloride:

logD & Acid/Base Dissociation Constant (Ka/Kb): Franzen, Ulrik; Electrophoresis 2009, V30(15), P2711-2719.

Solubility: 1) Hough, Whitney L.; New Journal of Chemistry 2007, V31(8), P1429-1436;

2) Hays, Patrick A.; Journal of Forensic Sciences 2005, V50(6), P1342-1360.

I believe that Prilocaine and its HCl salt would behave similar to Lidocaine and its HCl salt. You could evaluate it according to the information you get from the literature.

Best regards,

Esen

Dear Rene

open the following link, you will get answer for Prilocaine and its HCl

https://www.ebi.ac.uk/chembl/compound/inspect/CHEMBL1194

If you have ACD Labs, you could calculate pKa, logP and logD of the molecules. Also, most of the internet sources use these calculated values. Calculated values are good for quick evaluation but it is always better to use experimental data if available.

Thanks everybody!

I will perform a set of experiments to obtain the real results.

Have all a nice week!

Go to merck index, draw your compound structure, its will generate all required data, and ya acd labs chem office you can refer for same.

Refer 1) Hough, Whitney L.; New Journal of Chemistry 2007, V31(8), P1429-1436;

2) Hays, Patrick A.; Journal of Forensic Sciences 2005, V50(6), P1342-1360.

Luan, Feng; Pharmaceutical Research 2005, V22(9), P1454-1460.

PKa is constant in both form.......

Hello,

Solubility of correspondung salt and bases will be different.

Hi,

In principle, physchem properties should be different for a salt compared to a base or an acid. In practice, dissociation constant can be considered as independent from the form in most cases. In contrast, partition and distribution coefficients as well as solubility may diverge substantially.

In addition, please note that any tool of any package are not able to calculate logP, logD, solubility or other physchem properties. They use (often QSAR) models for prediction. This involves a bench of approximations, applicability domains and a wise analysis of the output.

Please find a list of such methods and many other modeling/cheminformatics/drug design tools at http://www.click2drug.org

Enjoy! Antoine.