1. INTRODUCTION
Coronavirus is a member of the Coronaviridae family, a coated RNA virus, causing a common pathogenesis between humans and animals [1]. The coronavirus family can cause different forms of disease varying from simple cold and gastrointestinal symptoms to pneumonia and bronchitis or acute respiratory distress syndrome (ARDS) [2-7].
Severe Acute Respiratory Syndrome-related Coronavirus (SARS-CoV) and Middle East Respiratory Syndrome-related Coronavirus (MERS-CoV) were some of the most important epidemics caused by coronaviruses in the form of severe pneumonia leading to ARDS [2, 8, 9]. COVID-19, in compression with other coronaviruses, has been reported to have a high prevalence and rapid transmission ability which caused the current pandemic in a very short time [10].
COVID-19 causes asymptomatic and symptomatic infections; symptomatic patients may present with broad manifestations from dry cough, sore throat, fever, myalgia, and shortness of breath to respiratory failure leading to intubation and mechanical ventilation [11]. In severe cases of COVID-19 infection, progression to sepsis and multiple organ failure has been reported [12-16]. The pathogenesis of COVID-19 infection combines primary viraemia and secondary inflammation resulting from cytokine storm; in patients with lung involvement this can lead to inflammation and destruction of the alveoli. Therefore, prevention of cytokine storm seems to be rational in the treatment of moderate to severe COVID-19 infection. Some medications such as hydroxychloroquine (HCQ) with anti-inflammatory properties and antiviral medications like lopinavir/ ritonavir have been reported to be effective in the treatment of SARS-CoV-2 [17-19]. Pentoxifylline is a well-known medication with anti-inflammatory properties, prescribing in the treatment of many clinical conditions [14, 19].
The anti-inflammatory effects of Pentoxifylline (PTX) include decreasing in the production of proinflammatory cytokines and inflammatory parameters such as TNF and IFN-gamma IL-6, and IL-1 which help suppress the inflammation [20, 21]. Moreover, PTX enhances the blood flow within narrow arteries, resulting in better circulation and oxygenation [22]. In the current study, the efficacy and safety of PTX in the treatment and recovery of patients with moderate to severe COVID-19 infection was investigated in a randomized controlled clinical trial.