A multicenter, double-blind, placebo-controlled, randomized, comparative study of the efficacy and safety of Meglumine acridone acetate (enteric-coated tablets, 150 mg) for post-exposure prophylaxis of influenza and other acute respiratory viral infections (ARVI) in adults was conducted. The study was performed in 6 centers in Russia according to the permission of the Ministry of Health of Russia to conduct clinical study No. 418 dated August 8, 2023. A total of 578 male and female subjects aged 18—65 years were randomized to group I (taking Meglumine acridone acetate 4 tablets (600 mg) daily) or group II (taking placebo 4 tablets daily) according to the scheme on days 1, 2, 4, 6, 8. The results showed statistically significant superiority of Meglumine acridone acetate over placebo. The odds ratio of not getting sick after close contact with a first-order patient was 3.651 (95% CI 1.753; 7.602). In the context of the cost-effectiveness analysis, it was found that in group I (Meglumine acridone acetate), the average costs per patient, taking into account patient’s expenditures, were 8.5% lower, taking into account the government’s expenditures, were 19.8% lower, and taking into account all costs (society perspective), they were 15.9% lower compared to group II (placebo). Thus, the clinical and pharmacoeconomic efficacy of Meglumine acridone acetate (enteric-coated tablets, 150 mg) compared with placebo was shown, and a favorable safety profile of the study drug was established when used for post-exposure prophylaxis of influenza and other ARVI in adults.