Table 2.

Potency comparison between phosphodiesterase inhibitors

	PDE4 inhibition (IC50, nM)a	TNF-α release (IC50, nM)a	Bronchorelaxation (EC50, μmol/kg)b	Dosage for COPD (mg, daily)c
Roflumilast	0.8	20	1.5	0.5
Cilomilast	120	1300	52.2	15 twice
Rolipram	1100	30	32.5	-
Theophylline	>10 000	>10 000	>300	100–600

^aLeadDiscovery; Yoshimura et al (1995); Tenor et al (1996).

^bBundschuh et al (2001; Holbrook et al (1996).

^cGOLD (2005); Gamble et al (2003); Rabe et al (2005); Lipworth (2005).