The efficacy and tolerability of GFF MDI (Bevespi Aerosphere®), a fixed-dose combination of glycopyrronium (GP)/formoterol fumarate dihydrate (FF) 14.4/10 μg (equivalent to glycopyrrolate/formoterol fumarate 18/9.6 μg) delivered by metered dose inhaler (MDI) using innovative co-suspension delivery technology, has been investigated in a Phase III clinical trial program (NCT01854645, NCT01854658, NCT01970878) in patients with COPD. Here, we present findings from a pharmacokinetic (PK) sub-study of NCT01854645 (PINNACLE-1).PINNACLE-1 was a multicenter, randomized, double-blind, parallel-group, 24 wk chronic-dosing, placebo- and active-controlled study. The PK sub-study assessed the systemic accumulation of glycopyrronium and formoterol following administration of GFF MDI 14.4/10 μg, GP MDI 14.4 μg, or FF MDI 10 μg (all BID) for 12 wks. Plasma for PK analysis was collected for up to 12 h after dosing, on Day 1 and Week 12.Of 2,103 patients randomized in PINNACLE-1, 292 participated in the PK sub-study. The plasma concentration-time profiles of glycopyrronium were similar following treatment with GFF MDI or GP MDI, both after single dosing and at Week 12. Accumulation at Week 12 relative to Day 1 was up to 2.30-fold for glycopyrronium. The plasma concentration-time profiles of formoterol were similar following treatment with GFF MDI or FF MDI, both after single dosing and at Week 12. Accumulation at Week 12 relative to Day 1 was up to 1.62-fold for formoterol.Overall, the results have characterized the accumulation of glycopyrronium and formoterol associated with GFF MDI, GP MDI, and FF MDI, and indicated that there were no meaningful PK interactions, whether drug-drug or due to formulation, between glycopyrronium and formoterol following treatment with GFF MDI formulated using co-suspension delivery technology.