PF-00610355 is ultra long-acting beta 2 adrenergic receptor-agonists that is being developed for ‘once daily’ treatment of asthma. Plasma pharmacokinetics of orally inhaled PF-00610355 are consistent and exhibit a sustained plateau after single/multiple doses, but plasma exposure is reduced in asthmatic patients compared with healthy volunteers. Although substantial increases in heart rate were observed in healthy volunteers, both pharmacokinetic as well as pharmacodynamic differences between healthy volunteers and chronic obstructive pulmonary disease (COPD) patients (the systemic exposure of PF-00610355 is substantially lower in COPD than in healthy volunteers) explain the modest effect of PF-00610355 on heart rate in the patient population. PF-00610355 had been in phase II clinical trials for the treatment of asthma and chronic obstructive pulmonary disease. However, this development was discontinued.