Safety, Tolerability, and Pharmacokinetics of SPL84 in Healthy Volunteers

Key Inclusion Criteria: * Male adults 18 to 50 years old * Considered healthy based on medical history, physical examination, 12-lead ECG and clinical laboratory results * Body Mass Index (BMI) 19.0-30.0 kg/m2 * Subjects who have no difficulties in receiving drugs by inhalation Key Exclusion Criteria: * A major surgical procedure or significant traumatic injury within 28 days prior to study intervention administration * Recent diagnosis of lung disease (\< 12 weeks from planned enrollment) * Any acute illness (e.g. acute infection) within 48 hours prior to the study intervention administration, which is considered of clinical significance by the Investigator. * Chronic respiratory disease including but not limited to obstructive airway disease such as asthma or chronic obstructive pulmonary disease (COPD); restrictive disease such as idiopathic pulmonary fibrosis (IPF); or pulmonary vascular disease such as pulmonary arterial hypertension (PAH). * History of adverse reactions during aerosol delivery of any medicinal product. * Total body weight ≤50 kg at screening. * Abnormal forced expiratory volume at one second (FEV1) at screening. * Oxygen saturation ≤95% at screening. * Alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyl transferase (GGT), alkaline phosphatase (ALP) and bilirubin (total and direct) above upper limit of normal (ULN) at screening and clinically significant * Supine systolic blood pressure \<90 or \>140 mmHg, supine diastolic blood pressure \<50 or \>90 mmHg, heart rate \<45 or \>100 beats per minute (bpm), or elevated body temperature (\>38ºC) at screening * Clinically significant ECG abnormalities at screening * Positive for SARS-CoV-19 at screening or Day -1 (baseline). * Positive serology tests for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), and hepatitis C virus (HCV) antibody at screening. * Positive urine drug, tobacco, and breath alcohol test result at screening or Day -1 (baseline). * Use of any prescription or over-the-counter (OTC) medications, including vitamins and herbal or dietary supplements within 14 days prior to dosing. * Subjects who have received any vaccines within 4 weeks prior to study intervention administration. * History or current drug/alcohol abuse (excluding use of medicinal cannabis for pain management). * History of smoking or vaping within 180 days (6 months) of screening