RationaleInhaled antimicrobials enable high local concentrations where needed and, compared to orally administration, greatly reduce the potential for systemic side effects. In SARS-CoV-2 infections, hydroxychloroquine (HCQ) administered as dry powder via inhalation could be safer than oral HCQ allowing for higher and therefore more effective pulmonary concentrations without dose limiting toxic effects.ObjectivesTo assess the local tolerability, safety and pharmacokinetic parameters of HCQ inhalations in single ascending doses of 5, 10 and 20 mg using the Cyclops dry powder inhaler.Methods12healthy volunteers were trained in inhaling HCQ correctly. Local tolerability and safety were assessed by pulmonary function tests, ECG and recording adverse events. To estimate systemic exposure, serum samples were collected before and 0.5, 2 and 3.5 h after inhalation.Results and discussionDry powder HCQ inhalations were well tolerated by the participants, except for transient bitter taste in all participants and minor coughing irritation. There was no significant change in QTc-interval or drop in FEV1 post inhalation. The serum HCQ concentration remained below 10 µg/L in all samples.ConclusionInhaled dry powder HCQ is safe and well tolerated. Our data support further studies with inhaled HCQ dry powder to evaluate pulmonary pharmacokinetics and efficacy is warranted.

Rationale Inhaled antimicrobials enable high local concentrations where needed and, compared to orally administration, greatly reduce the potential for systemic side effects. In SARS-CoV-2 infections, hydroxychloroquine sulphate (HCQ) administered as dry powder via inhalation could be safer than oral HCQ allowing higher and therefore more effective pulmonary concentrations without dose limiting toxic effects. Objectives To assess the local tolerability, safety and pharmacokinetic parameters of HCQ inhalations in single ascending doses of 5, 10 and 20 mg using the Cyclops dry powder inhaler. Methods Twelve healthy volunteers were included in the study. Local tolerability and safety were assessed by pulmonary function tests, electrocardiogram and recording adverse events. To estimate systemic exposure, serum samples were collected before and 0.5, 2 and 3.5 h after inhalation. Results and discussion Dry powder HCQ inhalations were well tolerated by the participants, except for transient bitter taste in all participants and minor coughing irritation. There was no significant change in QTc-interval or drop in FEV1 post inhalation. The serum HCQ concentration remained below 10 μg/L in all samples. Conclusion Single doses of inhaled dry powder HCQ up to 20 mg are safe and well tolerated. Our data support that further studies with inhaled HCQ dry powder to evaluate pulmonary pharmacokinetics and efficacy are warranted.