Hydroxychloroquine/azithromycin in COVID-19: The association between time to treatment...

Hydroxychloroquine/azithromycin in COVID-19: The association between time to treatment and case fatality rate

1. Introduction

The rapid spread of the virus referred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to a devastating worldwide pandemic. Despite the astonishingly rapid development of effective vaccines, most countries continue to suffer from the tragic consequences of the coronavirus disease 2019 (COVID-19). There is still a need for drugs that effectively control the disease. Unfortunately, COVID-19 has proven elusive and non-responsive to most treatment options as indicated by several clinical trials that failed to demonstrate a significant reduction in morbidity and mortality of COVID-19 patients [1,2]. Perhaps most disheartening is the fact that drugs proven to possess strong anti-infectious and anti-inflammatory properties and that have been successfully employed in other viral diseases failed to show a statistical improvement in several clinical trials in COVID-19 patients. Two concrete examples are Chloroquine (CQ) and its metabolite Hydroxychloroquine (HCQ). Successfully used to prevent and treat malaria and amebiasis for many years [3], these drugs yielded conflicting results in various clinical trials [4]. furthermore, its usage or treatment interruption could be confounded by the known side effects of CQ and HCQ which include mild gastrointestinal and more serious cardiovascular and neurological effects. This is a particularly important consideration when treating patients at risk of developing severe forms of COVID-19 [4,5].



However, notwithstanding the known limitations and well-justified reservation for the use of these drugs, there is one aspect that requires further investigation: the fact that in viral infections such as influenza, there is a relationship between early antiviral therapy and survival. It is the rapid elimination of pathogens and the early reduction in the viral load that seems to be decisive to avoid irreversible injury due to the progression of the disease [6]. This is particularly relevant for the use of CQ and HCQ in the context of COVID-19 [7], and much can be learned from countries that have considerable clinical experience with the use of these drugs in the treatment of malaria and other infectious diseases. Indeed, the healing properties of the bark of the tree Cinchona officinalis, the source of the natural quinine, were first discovered by the Incas, and clinically applied to cure malaria as early as the 1600s, making the Cinchona tree the national tree of Peru.


Thus, when the first case of COVID-19 was diagnosed in Peru on March 6th, 2020, clinicians experienced the use of HCQ in the treatment of other diseases that employed this drug to combat COVID-19. They based its use on their clinical experience and the knowledge that HCQ significantly decreases viral load in particular when associated with azithromycin (AZIT). To these clinicians, the long-term use of low doses of AZIT was known to reduce exacerbations of poorly controlled asthma, which has been attributed to the suppressive effect of AZIT on the inflammatory TNF pathways [8]. The use of this treatment regimen was further encouraged by early reports that HCQ not only decreased significantly the viral load but when associated with AZIT, was also able to control the infection in COVID-19 patients [9].


Chloroquine, the derivate of the natural quinine, is a 9-aminoquinoline that has first been described in 1934 and used to combat various viruses since 1960 [10]. In 1978 it was demonstrated that CQ is an anisotropic dibasic agent that increases the pH of lysosomes [11], and alters cellular metabolism [12]. This pH effect in lysosomes and other cytoplasmic organelles contributes to the suppression of viral replication. Together with its anti-inflammatory action as a suppressor of TNF alpha and Interleukin 6, this drug seems to be an ideal candidate to treat patients infected with SARS-CoV-2 [13]. In 2003 it was discovered that the S1 domain of the SARS-CoV protein binds to angiotensin-converting enzyme 2 (ACE2) for cell entry which opened the way for further in-depth mechanistic in vitro studies [14]. One of these studies demonstrated that CQ is an effective inhibitor of replication of the coronavirus SARS-CoV. These cell culture experiments demonstrated that the IC50 for the antiviral activity of CQ was significantly lower than its cytostatic activity, which was reflected in a high selectivity index of 30. Specifically, these studies indicated that the maximal concentration of its antiviral action (8.8 μM) was much lower than the concentration required for its mean cytotoxic effect (261.3 μM). As is the case for all in vitro assays, there are numerous caveats associated with the translation of such preclinical findings into the clinic. Nevertheless, such experiments are encouraging, since concentrations (CC50%) of 261.3 μM are much higher than those achieved in the blood at the therapeutic level of MIC50%, suggesting that CQ could potentially be an effective clinical agent against SARS-CoV [15]. Moreover, as demonstrated in another study cells previously treated with CQ are refractory to SARS-CoV infection, and when cells are already infected, CQ can prevent viral replication [16].




These encouraging results laid a solid scientific foundation for the use of CQ in the treatment of SARS-CoV-2. Indeed, various studies confirmed that the known antiviral properties of CQ also potently blocked SARS-CoV-2 infection at low concentration, with mild cytotoxicity and a high selectivity index (mean effective concentration (EC50%) = 1.13 μM; CC50 > 100 μM, SI > 88.50) [17]. Moreover, additional mechanisms have been identified. One study suggests that the binding of HCQ/CQ to sialic acids and ECA-2 receptor gangliosides prevents viral S protein from entering the cell [18], and a cell culture assay confirmed that HCQ/CQ blocks the transport of SARS-CoV-2 from early to late endosomes [19]. Another study tested 1520 compounds that are in clinical use and identified fifteen products effective against SARS-CoV-2. Among these products, HCQ and AZIT showed the highest antiviral activities (CE50% = 4.17 μM and 2.12 μM, respectively) and the highest SIs [20]. In both plasma and lung, CQ/HCQ has mean/median Cmax concentrations above the EC50, and both plus AZIT would reach lung concentrations 10 times higher than the EC50 [21]. Structurally, AZIT resembles the GM1 ganglioside of the ECA2 receptor, so it binds to the tip of the spike protein, while the CQ/HCQ molecules bind to the virus binding sites of sialic acids and ECA-2 gangliosides, generating a synergistic antiviral mechanism [22]. These in vitro studies suggest that the HCQ-AZIT combination has a synergistic effect on SARS-CoV-2 at concentrations that are compatible with those obtained in the human lung [23]. Furthermore, by binding to Sigma 1 and Sigma 2 receptors, HCQ effectively reduces the infectivity of SARS-CoV-2 [24].


The scientific data obtained for the Coronavirus as early as 2006 and confirmed for SARS-CoV-2 at the beginning of the pandemic, together with our extensive clinical experience in the use of CQ in treating malaria and other infectious diseases [3] provided a strong rationale for the therapeutic use of CQ in patients infected during the new coronavirus epidemic COVID-19. It also provided an impetus to test QC immediately in clinical trials [25].


In Peru, the Ministry of Health decided to use the HCQ/CQ combination with AZIT [26]. In the absence of clinical trial results during the early phase of the pandemic, physicians were instructed to apply their extensive clinical experience with the use of this drug combination in the context of the emerging understanding of the pathophysiology of SARS CoV-2 infection to determine the impact of early outpatient treatment on hospitalization and mortality [27]. In this report, we present the results in 1265 patients treated on an outpatient basis at the Centro Materno-Infantil (CMI) de Tahuantinsuyo Bajo, an I-4-level health center in the city of Lima.


2. Material and methods

The present study analyzed anonymized data from the database of COVID-19 patients attended at the CMI Tahuantinsuyo Bajo, a primary care facility in the city of Lima, between April 30 and September 30, 2020.


Patients arrived at a dedicated triage site for patients with suspected COVID-19 infection. There, vital signs were taken, including SpO2, and the attending physicians took the patient history and performed a clinical examination to determine whether they met COVID-19 patient clinical criteria according to the guidelines of the Peruvian Ministry of Health. All patients were registered in the respective epidemiological data file and the information included vital signs, comorbidities, symptoms, and treatment onset, consisting of 200 mg HCQ every 8 h for 7–10 days in combination with 500 mg AZIT on the first day, followed by 250 mg for 4 days. Data on days from symptom onset to treatment was collected as well. The patients were followed up with daily telephone controls and if any symptoms of deterioration or side effects appeared, they were summoned to the clinical facility. Follow-up was carried out not only with the patients but also with their contacts, to provide treatment as soon as the first symptoms appeared. Every day the epidemiology team recorded and shared patient information to the physician coordinating the COVID-19 registry. The information was transcribed into an Excel spreadsheet and the cases were followed up after discharge until they were sure of their condition. If the information could not be obtained by telephone, a home visit was done by the rapid response team also established under Peruvian COVID-19 guidelines.


The treatment started as soon as the attending physician determined that the patient exhibited symptoms that met the COVID-19 patient clinical criteria according to the guidelines of the Peruvian Ministry of Health. Some of these patients arrived at the hospital with a positive test, but most did not. Those that were not tested before arrival were asked to take the test. This test was not readily available at the center, albeit it continues to be offered at no cost at some government testing sites. Given that during the study period it could take almost a week to process and register the result of the NAAT test, and because tests tend to be less accurate within three days of exposure, the treatment regimen was started irrespective of any result if a patient met all the clinical criteria for COVID-19. Statistical analysis was performed with the Stata 14 statistical package (Stata Corporation, College Station, Texas, USA). Categorical variables were presented as frequencies and percentages and their respective 95% confidence intervals (95%CI), continuous variables as means or medians along with standard deviations (SD) or interquartile ranges (IQR). To determine the risk factors associated with death, a logistic regression analysis was performed, odds ratios were presented with their respective 95%CI and a p-value of less than 0.05 was considered statistically significant.


This study was approved by the Institutional Human Ethics Committee of the Universidad Peruana Cayetano Heredia (approval code: 203939). This study did not require individual consent from the participants because it analyzed de-identified data from an already existing database. Cayetano Heredia University's researchers analyzed the information that was previously registered and systematized by the team of physicians in charge of primary care at the health center.


3. Results

A total of 1265 clinically diagnosed COVID-19 patients were studied with an average age of 44.5 years, 50.1% being women, with a time of symptom onset to the treatment of 5.9 days, SpO2 of 97%, the temperature of 37.3 °C, with 41% with at least one comorbidity and 96.1% with at least one symptom or sign (Table 1). The most common comorbidities were obesity (17.3%), hypertension (8.3%), chronic respiratory disease (7.2%), and diabetes (6.1%) (Table 2). The most common symptoms were cough (85.1%), malaise (81.7%), sore throat (76.7%), the sensation of thermal rise (54.2%), and dyspnea (33.8%) (Table 3). | Plaquenil (hydroxychloroquine) | Sales of antibiotics and hydroxychloroquine | Hydroxychloroquine (Plaquenil) | Facts about chloroquine and hydroxychloroquine | get rx for hydroxychloroquine | hydroxychloroquine get you high | Hydroxychloroquine Uses | Side Effects of Plaquenil (Hydroxychloroquine) | Hydroxychloroquine tablets |

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