AZM is dibasic compared to the monobasic 14-member ring structure macrolides.
The pKa value of AZM describing the two nitrogen groups undergoing dissociation is 8.85 (8.8 and 8.9) and almost equal to the pKa 8.6–8.9 of erythromycin (Goldman et al.,1990).
At physiological pH, both antimicrobial agents are protonated and