key: cord-0989301-roe6g61u authors: Formiga, Fabio Rocha; Leblanc, Roger; de Souza Rebouças, Juliana; Farias, Leonardo Paiva; de Oliveira, Ronaldo Nascimento; Pena, Lindomar title: Ivermectin: An award-winning drug with antiviral expectations against COVID-19 date: 2020-10-07 journal: J Control Release DOI: 10.1016/j.jconrel.2020.10.009 sha: 29e37e01ceb7ce605bc41d88e2c2ebb6995ee029 doc_id: 989301 cord_uid: roe6g61u Ivermectin is an FDA-approved broad-spectrum antiparasitic agent with demonstrated antiviral activity against a number of DNA and RNA viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite this promise, the antiviral activity of ivermectin has not been consistently proven in vivo. While ivermectin's activity against SARS-CoV-2 is currently under investigation in patients, insufficient emphasis has been placed on formulation challenges. Here, we discuss challenges surrounding the use of ivermectin in the context of coronavirus disease-19 (COVID-19) and how novel formulations employing micro- and nanotechnologies may address these concerns. SARS-CoV-2 in Vero/hSLAM cells by 5,000-fold. This finding has generated great interest and excitement among physicians, researchers and public health authorities around the world. However, these results should be interpreted with caution. Firstly, it is important to note that the drug was only tested in vitro using a single line of monkey kidney cells engineered to express human signaling lymphocytic activation molecule (SLAM), also known as CDw150, which is a receptor for the measles virus [10] . Also, ivermectin has not been tested in any pulmonary cell lines, which are critical for SARS-CoV-2 in humans [11] . Furthermore, these authors did not show whether the reduction seen in RNA levels of SARS-CoV-2 following treatment with ivermectin would indeed lead to decreased infectious virus titers. Importantly, the drug concentration used in the study (5 μM) to block SARS-CoV-2 was 35-fold higher than the one approved by the FDA for treatment of parasitic diseases, which raises concerns about its efficacy in humans using the FDA approved dose in clinical trials [12] . In light of the potential of ivermectin to prevent replication in a broad spectrum of viruses, the inhibition of importin α/β1-mediated nuclear import of viral proteins is suggested as the probable mechanism underlying its antiviral activity [6] . Since SARS-CoV-2 is an RNA virus, a similar mechanism of action may take place [9] . A possible ionophore role for ivermectin has also been reported [13] . Since ionophore molecules have been described as potential antiviral drugs [14] , ivermectin could ultimately induce an ionic imbalance that disrupts the potential of the viral membrane, thereby threatening its integrity and functionality. The pathology of COVID-19 is characterized by the rapid replication of SARS-CoV-2, triggering an amplified immune response that may lead to cytokine storm, which frequently induces a severe inflammatory pulmonary response [15] . Disease progression may result in progressive respiratory failure arising from alveolar damage, and can lead to death [16] . Moreover, the monitoring of SARS-CoV-2 viral load in the upper respiratory tract and bronchoalveolar lavage fluid (BALF) in patients with severe disease indicates higher loads, as well as greater viral persistence [16, 17, 18, 19] . In addition to the indication for antiviral therapy, anti-inflammatory intervention may also be necessary to prevent acute lung injury in SARS-CoV-2 infection. With regard to its anti-inflammatory properties, ivermectin have been shown to mitigate skin J o u r n a l P r e -p r o o f inflammation [20] . Importantly, ivermectin significantly diminished the recruitment of immune cells and cytokine production in BALF assessed in a murine model of asthma [21] . A study evaluating the ability of ivermectin to inhibit lipopolysaccharide (LPS)induced inflammation revealed significantly decreased production of TNF-alpha, IL-1ss and IL-6 in vivo and in vitro [22] . Further studies may establish the role of ivermectin on inflammatory response caused by SARS-CoV-2, whether besides the antiviral activity ivermectin could play a supportive adjuvant role facing the hostile infection microenvironment. With regard to investigations into potential drug treatments against COVID-19, ivermectin has received particular attention. Indeed, a number of clinical studies have been conducted in various countries such as USA, India and Egypt, as registered on the repository of data ClinicalTrials.gov. Table 1 shows a compilation of these studies, with patients receiving monotherapy or combination therapy, using different approaches of ivermectin dosing. In Spain, the SAINT clinical trial is currently underway and aims to determine the efficacy of a single dose of ivermectin, administered to low risk, nonsevere COVID-19 patients [23] . Despite the fact that ivermectin has been shown to be effective in vitro against Sars-Cov-2, it is possible that the necessary inhibitory concentration may only be achieved via high dosage regimes in humans. The enthusiasm surrounding ivermectin use is restrained by a lack of appropriate formulations capable of providing improved pharmacokinetics and drug delivery targeting mechanisms. Although patients could be treated using systemic therapy, high-dose antiviral therapy could lead to severe adverse effects. Regardless, no commercially available injectable forms of ivermectin are available for human use. In COVID-19 patients, the rapid evolution of disease requires prompt treatment, as therapeutic intervention must be introduced within a narrow window of time. Considering that the respiratory tract has been shown to be a primary site of infection, the delivery of ivermectin by pulmonary route would provide high drug deposition in the airways and lungs to mitigate the high viral loads seen in these sites. It is worth noting that inhalation therapy has been reported to be the most effective treatment for respiratory infections due to increased drug bioavailability [24, 25] . Indeed, pulmonary and nasal administration bypasses the first-pass metabolism observed in oral administration and the lungs and nasal cavity are known to be low drug-J o u r n a l P r e -p r o o f Journal Pre-proof metabolizing environments [26] . In severe cases of SARS-CoV-2-induced pneumonia, antiviral aerosol formulations could be delivered by inhalation to patients on mechanical ventilation. In addition, patients presenting mild symptoms of COVID-19 could benefit from being treated with antiviral aerosol formulations at earlier stages of disease. Importantly, Gilead Sciences recently announced human trials of an inhaled version of its antiviral drug remdesivir for non-hospitalized patients [27] . Despite its promising antiviral and preliminary anti-inflammatory potential, the development of ivermectin formulations presents challenges, primarily due to its property of poor water solubility. Consequently, ivermectin's oral bioavailability remains low [28] . In addition, its pharmacokinetic profile may be affected by specific formulations, and minor differences in formulation design can modify plasma kinetics, biodistribution, and, consequentially, efficacy. For instance, ivermectin does not achieve adequate concentration levels in the human bloodstream necessary for treatment efficacy against ZIKV [29] . Therefore, novel delivery strategies are needed to optimize ivermectin bioavailability. Micro-and nanocarriers offer several advantages in drug delivery, namely: specific targeting, high metabolic stability, high membrane permeability, improved bioavailability, controlled release and long-lasting action [30] . In light of these attributes, some studies have formulated ivermectin in micro-and nanoparticles, either using lipid nanocapsules [31] , chitosan-alginate nanoparticles [32] or poly (lactic-coglycolic acid) (PLGA) micro-and nanoparticles [33, 34] . For antiviral purposes, ivermectin has been formulated in liposomes [35] and PLGA nanoparticles [29] . The latter ivermectin nanoformulation was shown to cross the intestinal epithelial barrier when administered via oral route, with considerable concentrations detected in the blood, enabling its potential application in ZIKV therapy. Appropriate drug formulations must address inherent limitations, including poor water-solubility and difficulty in drug delivering to desired target areas, notably the pulmonary environment. As previously mentioned, micro-and nanocarriers have been investigated in an effort to optimize ivermectin bioavailability. In the context of pulmonary delivery, these drug delivery systems can be modified to attend suitable aerodynamic size ranges for the airways and alveolar deposition. Smaller particles achieve a greater deposition in the lungs compared to larger particles. Particles smaller J o u r n a l P r e -p r o o f than 5 µm follow the airflow beyond the retro-pharynx and reach the trachea. Particles with an aerodynamic diameter of about 2 to 5 µm are deposited in the upper respiratory tract at the level of the trachea and tracheal bifurcation. Particles smaller than 2 µm deposit in the lower airway and alveolar epithelia [36, 37] . Nanoparticulate systems, upon release in aerosol, form aggregates in the micrometer size range. These aggregates are believed to have sufficient mass to be deposited in the bronchiolar region and remain for an extended period, hence achieving the desired effect [38] . It follows that ivermectin formulations produced at the desired particle sizes will allow for particle deposition in either the lower airway or alveolar epithelia, which will then trigger rapid drug release, accelerating the onset of therapeutic activity. We hypothesize that micro-and nanotechnology-based systems for the pulmonary Anti-parasite Drugs Sweep Nobel Prize in Medicine Ivermectin inhibits DNA polymerase UL42 of pseudorabies virus entrance into the nucleus and proliferation of the virus in vitro and vivo The FDA-approved Drug Ivermectin Inhibits the Replication of SARS-CoV-2 in Vitro Measles viruses on throat swabs from measles patients use signaling lymphocytic activation molecule (CDw150) but not CD46 as a cellular receptor Histopathologic changes and SARS-CoV-2 imunostaining in the lung of a patient With COVID-19 The Approved Dose of Ivermectin Alone is not the Ideal Dose for the Treatment of COVID-19 Ivermectin, antiviral properties and COVID-19: a possible new mechanism of action Novel ionophores active against La Crosse Virus identified through rapid antiviral screening SARS-CoV-2: A Storm Is raging A pneumonia outbreak associated with a new coronavirus of probable bat origin Virological assessment of hospitalized patients with COVID-2019 SARS-CoV-2 Viral load in J o u r n a l P r e -p r o o f upper respiratory specimens of infected patients Viral load dynamics and disease severity in patients infected with SARS-CoV-2 in Retrospective Cohort Study Topical ivermectin in the treatment of Papulopustular Rosacea: A systematic review of evidence and clinical guideline recommendations Anti-inflammatory effects of ivermectin in mouse model of allergic asthma Ivermectin inhibits LPS-induced production of inflammatory cytokines and improves LPS-induced survival in mice Ivermectin Navarra-ISGlobal Trial (SAINT) to evaluate the potential of ivermectin to reduce COVID-19 transmission in low risk, non-severe COVID-19 patients in the First 48 Hours after symptoms onset: A structured summary of a study protocol for a randomized Control Pilot Trial Challenges and strategies in drug delivery systems for treatment of pulmonary infections Inhaled formulations and pulmonary drug delivery systems for respiratory infections Strategies to enhance drug absorption via nasal and pulmonary routes An Open Letter from Daniel O'Day, Chairman & CEO Oral absorption of poorly water-soluble drugs: computer simulation of fraction absorbed in humans from a miniscale dissolution test Orally administrable therapeutic synthetic nanoparticle for Zika virus Nanodrugs: pharmacokinetics and safety Ivermectin lipid-based nanocarriers as novel formulations against head lice Improved antifilarial activity of ivermectin in chitosan-alginate nanoparticles against human lymphatic filarial parasite, Brugia malayi Therapeutic efficacy of poly (lactic-co-glycolic acid) nanoparticles encapsulated ivermectin (nano-ivermectin) against brugian filariasis in experimental rodent model Ivermectin-loaded microparticles for parenteral sustained release: In vitro characterization and effect of some formulation variables Liposomal systems as nanocarriers for the antiviral agent Ivermectin Physicochemical properties affecting the fate of nanoparticles in pulmonary drug delivery Drug delivery to the lungs: Challenges and Opportunities Nanoparticle-Mediated pulmonary drug delivery: A review Nanomaterials designed for antiviral drug delivery transport across biological barriers Nano Research for COVID-19 We would like to thank FACEPE (Pernambuco, Brazil), CNPq (Brazil), Inova Fiocruz (Brazil) and IDRC (Canada) for financial support. The authors also acknowledge the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -Brasil (CAPES) -Finance Code 001. The authors are grateful to Andris K. Walter for critical manuscript review and English language copyediting services. The authors deny the existence of any conflicts of interest.