Table IV.

Physicochemical Properties of Model Compounds

Physical properties	Buspirone (15, 55)	Bupivacaine (56, 57)	Antipyrine (51, 58)	Caffeine (38, 59)
Molecular weight	385.5	288	188.23	194.19
Aqueous solubility	0.5 mg/mL	1.16 mg/mL	1,100 mg/mL	21 mg/mL
pKa	4.12, 7.32	8.1	1.45	10.4
log P	2.78	3.70	0.39	−0.07
log D	2.80	2.48	0.39	−0.07