pKa of lidocaine:

Lidocaine hydrochloride is very soluble in water and alcohol and soluble in chloroform, but it is insoluble in ether. Lidocaine hydrochloride has a pKa of 7.86. Gebauer et al. developed a method for the study of lidocaine and oxycodone stability in a rectal gel. The dissociation constants (pKa) for popular local anesthetics used in dentistry are: Mepivacaine 7.6 Etidocaine 7.7 Lidocaine 7.9 Prilocaine 7.9 Bupivacaine 8.1 Tetracaine 8.5 Procaine 9.1 Ref: Monheim’s Local anesthesia 1st  ed page no 130