Abstract Aims This work assessed the pharmacokinetics (PK), safety and tolerability of glasmacinal (EP395, an oral anti‐inflammatory macrolide with negligible antimicrobial activity in development for COPD treatment) in two healthy participant trials: ‘first‐in‐human’ (FIH) and ‘drug–drug‐interaction’ (DDI). Methods The FIH trial was a randomized, double‐blind, placebo‐controlled trial of single (20–750 mg) and multiple (120–375 mg daily for 28 days) doses of glasmacinal. The DDI trial was an open‐label assessment of the effect of verapamil (moderate CYP3A4 inhibitor and P‐gp inhibitor) on the PK of glasmacinal, and the effect of glasmacinal on the PK of midazolam (CYP3A4 substrate) and digoxin (P‐gp substrate). Results No SAEs or severe AEs occurred, and no AEs considered related to glasmacinal led to withdrawal. Glasmacinal was rapidly absorbed, reaching peak plasma concentrations at ~4 h post‐dose and a terminal half‐life ~70 h. Glasmacinal systemic exposure ( C max and AUC 0–inf ) was reduced by one third when administered after food (300‐mg single dose, parallel group comparison). Co‐administration of glasmacinal with verapamil increased glasmacinal exposure ( C max 1.70‐fold [90% CI: 1.52, 2.39], AUC 0–inf 2.41‐fold [90% CI: 2.18, 2.82]). Glasmacinal modestly increased exposure to midazolam ( C max 1.26‐fold [90% CI: 1.12, 1.49], AUC 0–inf 1.54‐fold [90% CI: 1.33, 1.89]) and digoxin ( C max 1.38‐fold [90% CI: 1.22, 1.81] and AUC 0–inf 1.37‐fold [90% CI: 1.26, 1.52]). Conclusions Glasmacinal was well tolerated in single doses up to 750 mg and repeat doses up to 375 mg. Glasmacinal may be a victim of selected drugs that impact CYP3A4 and/or P‐gp but is unlikely to be a perpetrator of clinically relevant DDIs.