Antiviral efficacy of RAY1216 monotherapy and combination therapy with ritonavir in patients with COVID-19: a phase 2, single centre, randomised, double-blind, placebo-controlled trial.

Background: This study aimed to evaluate the efficacy and safety of RAY1216, a novel inhibitor of 3-chymotrypsin-like cysteine protease (3CLpro), in adults with coronavirus disease 2019 (COVID-19). Methods: This phase 2, single centre, randomised, double-blind, placebo-controlled trial included hospitalised patients between August 14, 2022, and September 26, 2022, in Sanya Central Hospital (The Third People's Hospital of Hainan Province) in China with no severe symptoms if they had laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection for not more than 120 h (5 days) and a real-time quantitative polymerase chain reaction (qPCR) cycle threshold (Ct) value of ≤30 for both the open reading frames 1 ab (ORF1ab) and nucleocapsid (N) genes within 72 h before randomisation. Half of the participants (n = 30) were randomly assigned (2:1) to receive either RAY1216 or a matched placebo three times a day (TID) for 5 days (15 doses in total), while the other half received RAY1216 plus ritonavir (RAY1216 plus RTV) or a matched placebo every 12 h for 5 days (10 doses in total). The primary endpoint was the time of viral clearance. Secondary outcomes included the changes of the SARS-CoV-2 RNA viral load, the positivity rate of the nucleic acid test, and the recovery time of clinical symptoms. A safety evaluation was performed to record and analyse all adverse events that occurred during and after drug administration as well as any cases in which dosing was halted because of these events. Clinicaltrials.gov identifier: ChiCTR2200062889. Findings: The viral shedding times in the RAY1216 and RAY1216 plus RTV groups were 166 h (95% confidence interval (CI): 140-252) and 155 h (95%CI: 131-203), respectively, which were 100 h (4.2 days) and 112 h (4.6 days) shorter than that of the placebo group, respectively (RAY1216 group vs. Placebo p = 0.0060, RAY1216 plus RTV group vs. Placebo p = 0.0001). At 24 h, 72 h, and 120 h after administration, the viral RNA loads in the RAY1216 and RAY1216 plus RTV groups were significantly less than those of the placebo groups. At 280 h (11.5 days) after administration, the nucleic acid test results in the RAY1216 and RAY1216 plus RTV groups were both negative. The common adverse events related to the investigational drugs were mild and self-limiting laboratory examination abnormalities. Interpretation: Our findings suggest that RAY1216 monotherapy and RAY1216 plus ritonavir both demonstrated significant antiviral activity and reduced the duration of COVID-19 while maintaining a satisfactory safety profile. Considering the limited clinical application of RTV, it is recommended to use RAY1216 alone to further verify its efficacy and safety. Funding: This study was sponsored by the Key Research and Development Program of China (2022YFC0868700).

Diffusion of size bidisperse spheres in dense granular shear flow.

Diffusion is an important particle behavior in granular flow. Although granular diffusion has been studied for decades, the diffusion of size bidisperse particles has not been well understood. In this paper, discrete element method simulations with the Lees-Edwards boundary condition are performed to quantify the relation between the diffusion coefficient (D) and flow parameters for size bidisperse spheres in dense granular flow. The influences of the shear rate (γ[over ̇]), the solids fraction (f), and the diameter ratio (D_{LS}) of particles on diffusion are studied. The effects of the friction coefficient (µ) and the restitution coefficient (e) are also investigated. The results indicate that while small particles diffuse faster than large particles in a binary system the volume weighted average diffusion coefficient is proportional to the shear rate and the square of the volume weighted average particle diameter, d^{2}, and it is inversely proportional to the solids fraction. The quantified relation is given as D=k_{d}γ[over ̇]d^{2}, where k_{d}=0.0186/f, and this relation is not sensitive to the diameter ratio for D_{LS}≤3. The diffusion coefficient is not sensitive to the friction coefficient except for the extreme condition where µ<0.1, and it is also not sensitive to the restitution coefficient between 0.3 and 0.9.