Table 2. Significant Functional Group–Protein Binding Associations.

functional group	cephalosporins containing noted group	correlation coefficient (±r)	p value
tetrazole	cephazolin, cefotetan, cefoperazone	+0.47	<0.05
pyridinium	ceftazidime, ceftaroline	–0.44	<0.05
primary amine	cephalexin, cefadroxil, ceftolozane, cefaclor, cefprozil	–0.43	<0.05
quaternary amine	ceftolozane, ceftazidime, ceftaroline, cefpirome, cefepime	–0.57	<0.01