PF-03635659

PF-03635659 is a potent, long-acting muscarinic M3 receptor antagonist developed as an inhaled therapy for chronic obstructive pulmonary disease (COPD). It exhibits a very slow dissociation rate from the M3 receptor (>1440 minutes), enabling once-daily dosing and providing 24-hour bronchodilation after a single inhaled dose. Clinical studies in healthy volunteers and patients with moderate COPD demonstrated effective bronchodilation and an adverse event profile comparable to tiotropium bromide, with common side effects including tachycardia and dry mouth. The drug was developed by Pfizer and reached phase II clinical trials for COPD but development has since been discontinued[1][2][4][5][7].