Assessment of the therapeutic efficacy and safety of meglumine acridonacetate (preparation Cycloferon®) in adult patients with acute respiratory viral infections has been carried out. Post-registration multicentre prospective non-interventional study of therapeutic efficacy and safety of Cycloferon in adult patients with ARVI has been carried out at 15 medical institutions in St. Petersburg and Moscow with the participation of 742 male and female patients in outpatient settings. The study included 4 visits to the clinical center: on days 1, 3, 5 and 9, with the 1st visit coinciding with the start of therapy. All patients received basic antiviral therapy: 600 mg Cycloferon tablets on days 1, 2, 4, 6 and 8 or umifenovir capsules 200 mg 4 times a day for 5 days. Also, all patients received symptomatic therapy. The study drugs were prescribed by a physician in accordance with the approved instructions for medical use and established clinical practice of the health care facility. Among included, 676 patients participants completed the study without significant deviations from the protocol and had sufficient compliance. 316 patients were included in the Cycloferon group, and 360 patients were included in the umifenovir group. PCR-based diagnostics of naso-oropharyngeal swab was performed on all patients at screening. Efficacy was assessed by the duration of hyperthermia, severity of symptoms on the WURSS-21, CCQ scales, duration of the period of temporary disability and the need for systemic antibacterial therapy. The results of the study showed the advantage of basic therapy for ARVI with Cycloferon compared to basic therapy for ARVI with umifenovir in outpatients with ARVI, with comparable high safety rates. The duration of hyperthermia (24 hours) differed significantly between the study groups, favoring Cycloferon (3.66 days in the Cycloferon group, 4.06 days in the umifenovir group, p = 0.01). The dynamics profile assessed using the AUC value for the sum of points on the WURSS-21 questionnaire for visits 2, 3 and 4 differed between the study groups, in the Cycloferon group it was 34.69 ± 21.74, in the umifenovir group 41.49 ± 29.93 (p = 0.035). The change in total CCQ score at each visit was significantly (p < 0.001) lower relative to visit 1 in both groups. CCQ symptom severity was lower in the Cycloferon group at all visits (p < 0.05). The mean duration of temporary disability was shorter in the Cycloferon group compared to umifenovir (median value of 5 and 7 days respectively, p < 0.001). The study established a comparably high safety profile for the investigational drugs. © 2024 Folium Ltd. All rights reserved.