1,3-diethyl-8-phenylxanthine ( dpx ; ki 0.14 mumol/l ) was the most potent analogue , followed by 8-phenyltheophylline ( ki 0.55 mumol/l ) , 3-isobutyl-1-methylxanthine ( ibmx ; ki 2.9 mumol/l ) and theophylline ( ki 8.1 mumol/l ) .
C0000096
ibmx
C0039771
theophylline