Triprolidine for COVID-19

ABSTRACT Numerous host factors, in addition to human angiotensin-converting enzyme 2 (hACE2), have been identified as coreceptors of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), demonstrating broad viral tropism and diversified druggable potential. We and others have found that antihistamine drugs, particularly histamine receptor H1 (HRH1) antagonists, potently inhibit SARS-CoV-2 infection. In this study, we provided compelling evidence that HRH1 acts as an alternative receptor for SARS-CoV-2 by directly binding to the viral spike protein. HRH1 also synergistically enhanced hACE2-dependent viral entry by interacting with hACE2. Antihistamine drugs effectively prevent viral infection by competitively binding to HRH1, thereby disrupting the interaction between the spike protein and its receptor. Multiple inhibition assays revealed that antihistamine drugs broadly inhibited the infection of various SARS-CoV-2 mutants with an average IC50 of 2.4 µM. The prophylactic function of these drugs was further confirmed by authentic SARS-CoV-2 infection assays and humanized mouse challenge experiments, demonstrating the therapeutic potential of antihistamine drugs for combating coronavirus disease 19. IMPORTANCE In addition to human angiotensin-converting enzyme 2, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can utilize alternative cofactors to facilitate viral entry. In this study, we discovered that histamine receptor H1 (HRH1) not only functions as an independent receptor for SARS-CoV-2 but also synergistically enhances ACE2-dependent viral entry by directly interacting with ACE2. Further studies have demonstrated that HRH1 facilitates the entry of SARS-CoV-2 by directly binding to the N-terminal domain of the spike protein. Conversely, antihistamine drugs, primarily HRH1 antagonists, can competitively bind to HRH1 and thereby prevent viral entry. These findings revealed that the administration of repurposable antihistamine drugs could be a therapeutic intervention to combat coronavirus disease 19.

Background and Objectives This study was aimed to determine the effect of antihistamines on Covid-19 disease. Subjects and Methods Two researchers searched online electronic databases PubMed, MEDLINE and Google Scholar from the beginning of the pandemic until December 30, 2022 using Mesh and keywords such as: "SARS-CoV-2" or "COVID-19" and "Antihistamine". Results The results depicted that levocetirizine, diphenhydramine, hydroxyzine, azelastine, dexchlorpheniramine, cetirizine, loratadine, desloratadine, fexofenadine, triprolidine, dimetindene, and famotidine are effective in treating and reducing the symptoms of Covid-19. Among them, famotidine had contradictory results, and although it may be a useful supplement in the treatment of covid-19, laboratory studies have failed to show the direct role of famotidine in controlling this disease. Conclusion From the above-discussed findings regarding antihistamines and Covid-19, specific antihistamines should be identified and included as an essential therapeutic approach for the management of Covid-19 alongside other approaches. In fact, antihistamines appear to be promising in the management of Covid-19 with a short time to relieve symptoms while giving the body enough time to reset its defense mechanism, thus reaching a rapid recovery. They work by both modulating histamine pathways and suppressing virus growth. Despite the fact that more trials and clinical studies still need to be done on the identification and deployment of potential antihistamines in the management of Covid-19, there is not enough time for this given the enormous threat of this global health crisis. Selective antihistamines, particularly histamine H1 receptor antagonists, should now be approved for emergency use for the management of Covid-19.