AIM OF THE STUDY: Chemico-biological standardization with respect to its vasorelaxation potential is the main objective of the present study. To investigate the vasorelaxation potential of key phytochemical of KGR, i.e., ethyl-p-methoxycinnamate (EPMC) and to study it's the mechanism of action.

MATERIALS AND METHODS: A HPLC method was developed and validated for the quality assessment of KGR using its two major phytochemicals i.e. ethyl-p-methoxycinnamate (EPMC) and ethyl cinnamate (EC) in KGR. The vasorelaxation effect of major phytochemicals of KGR was evaluated on the main mesenteric arteries isolated from male Wistar rats. Specific BKca channel blocker tetraethylammonium (TEA), receptor antagonist, nitric oxide scavenging capacity, and antioxidant potential were also evaluated for its plausible mechanism.

RESULTS: Present validated HPLC method facilitates simultaneous quantitation of EPMC and EC faster than classical GC techniques. EPMC has shown a dose-dependent relaxation in rat main mesenteric arteries (MMA) contracted by U46619 with an Emax of 58.68 ± 3.31%. Similarly, in endothelium-denuded MMA rings, relaxation was also observed (Emax of 61.83 ± 3.38%). Moreover, relaxation response to EPMC has strongly inhibited (Emax 14.76 ± 2.29%) when the tissue exposed to depolarizing high K+ containing buffer for the contraction. The point correlation dimension (pD2) values were also significantly decreased in high K+ treated arterial rings compared to control. Interestingly, when MMA rings incubated with a specific BKca channel blocker (TEA, 1 mM), the relaxation response to EPMC was also significantly blocked.

CLINICAL QUESTION: What is the role of drugs in the treatment of patients with covid-19?

CONTEXT: The evidence base for therapeutics for covid-19 is evolving with numerous randomised controlled trials (RCTs) recently completed and underway. Emerging SARS-CoV-2 variants and subvariants are changing the role of therapeutics.

WHAT IS NEW?: The guideline development group (GDG) defined 1.5% as a new threshold for an important reduction in risk of hospitalisation in patients with non-severe covid-19. Combined with updated baseline risk estimates, this resulted in stratification into patients at low, moderate, and high risk for hospitalisation. New recommendations were added for moderate risk of hospitalisation for nirmatrelvir/ritonavir, and for moderate and low risk of hospitalisation for molnupiravir and remdesivir. New pharmacokinetic evidence was included for nirmatrelvir/ritonavir and molnupiravir, supporting existing recommendations for patients at high risk of hospitalisation. The recommendation for ivermectin in patients with non-severe illness was updated in light of additional trial evidence which reduced the high degree of uncertainty informing previous guidance. A new recommendation was made against the antiviral agent VV116 for patients with non-severe and with severe or critical illness outside of randomised clinical trials based on one RCT comparing the drug with nirmatrelvir/ritonavir. The structure of the guideline publication has also been changed; recommendations are now ordered by severity of covid-19.

ABOUT THIS GUIDELINE: This living guideline from the World Health Organization (WHO) incorporates new evidence to dynamically update recommendations for covid-19 therapeutics. The GDG typically evaluates a therapy when the WHO judges sufficient evidence is available to make a recommendation. While the GDG takes an individual patient perspective in making recommendations, it also considers resource implications, acceptability, feasibility, equity, and human rights. This guideline was developed according to standards and methods for trustworthy guidelines, making use of an innovative process to achieve efficiency in dynamic updating of recommendations. The methods are aligned with the WHO Handbook for Guideline Development and according to a pre-approved protocol (planning proposal) by the Guideline Review Committee (GRC). A box at the end of the article outlines key methodological aspects of the guideline process. MAGIC Evidence Ecosystem Foundation provides methodological support, including the coordination of living systematic reviews with network meta-analyses to inform the recommendations. The full version of the guideline is available online in MAGICapp and in PDF on the WHO website, with a summary version here in The BMJ. These formats should facilitate adaptation, which is strongly encouraged by WHO to contextualise recommendations in a healthcare system to maximise impact.