Use of ivermectin in the treatment of Covid-19: A pilot trial.

OBJECTIVES: In this randomized open-label trial pilot study we assessed the antiviral effects and safety of various doses of ivermectin in patients with mild clinical symptoms of COVID-19.
METHODS: Patients were randomly assigned to receive standard of care (SOC) treatment at hospital admission; SOC plus ivermectin 100 mcg/kg; SOC plus ivermectin 200 mcg/kg; or SOC plus ivermectin 400 mcg/kg. The primary assessed endpoint was the proportion of patients who achieved two consecutive negative SARS-CoV-2 RT PCR tests within 7 days of the start of the dosing period. This study was registered at ClinicalTrials.gov (NCT04431466).
RESULTS: A total of 32 patients were enrolled and randomized to treatment. SOC treatment together with ivermectin did not result in any serious adverse events. All patients exhibited a reduction in SARS-CoV-2 viral load within 7 days; however, those who received ivermectin had a more consistent decrease as compared to the SOC alone group, characterized by a shorter time for obtaining two consecutive negative SARS-CoV-2 RT PCR tests.
CONCLUSIONS: Ivermectin is safe in patients with SARS-CoV-2, reducing symptomatology and the SARS-CoV-2 viral load. This antiviral effect appears to depend on the dose used, and if confirmed in future studies, it suggests that ivermectin may be a useful adjuvant to the SOC treatment in patients with mild COVID-19 symptoms.

Introduction

Ivermectin is a well-known antiparasitic, highly effective against helminthic infestations and with an excellent safety profile. In the past few years, studies have shown that ivermectin also has an antiviral effect on DNA and RNA viral families, preventing the virus from entering cells; promoting inhibition of the transporter complex "nuclear transporter mediated by α / β importin", fundamental to the viral replication process; and binding to RNA-dependent RNA polymerases, also leading to disruption of viral replication [[1], [2], [3], [4]].

Countries where the use of ivermectin against parasitic infections is common, such as in Africa, have significantly lower incidence of COVID-19. More recently, ivermectin’s antiviral effect was tested in vitro in Vero/hSLAM cells infected with SARS-CoV-2 (isolate Australia/VIC01/2020) [5].⁠ After 48 h, there was a 5000-fold reduction in viral RNA in ivermectin-treated samples as compared to controls. Although these findings highlighted the potential use of ivermectin as an antiviral drug in the fight against COVID-19, the dose used was 200 times greater than those commonly used in clinical indications [6].

Nevertheless, the negative impact of COVID-19 global pandemic and the urgent demand for an efficacious, safe, and widely available treatment for the disease has led to a widely spread prescription of ivermectin as a treatment option for SARS-CoV-2 infection. However, the information on the anti-SARS-CoV-2 activity of ivermectin in vivo is scarce. Thus, the primary objective of the present study was to assess the antiviral effects and safety of different doses of ivermectin in patients with mild COVID-19 symptoms.

Materials and methods

Trial design and setting

This is a single-centre, open-label trial of ivermectin in patients with mild COVID-19. The trial was conducted in accordance with Good Clinical Practice guidelines and the Declaration of Helsinki, and the protocol was approved by the National Ethics Advisory Committee before study initiation (CAAE: 31089520.2.0000.5504). All patients provided written informed consent to participate. The study was registered at ClinicalTrials.gov (NCT04431466).

Participants

Patients were enrolled if they met the following criteria: ≥18 years of age; an Eastern Cooperative Oncology Group (ECOG) score of 0–1; a National Early Warning Score (NEWS) of 0–4; and had SARS-CoV-2 infection confirmed by real-time reverse transcription polymerase chain reaction (RT-PCR) testing performed on nasopharyngeal swab specimens. Patients were excluded from the study if they were not able to ingest / absorb the drug orally through spontaneous ingestion or by gastro / enteral tubes; any clinical observation (clinical / physical evaluation) or laboratory findings which, in the investigator's opinion, would have put the patient at risk to participate in the study; any abnormal ECG findings that require additional evaluation; known hypersensitivity to the drug components used during the study; pregnancy or breastfeeding; body weight less than 15 kg; an estimated glomerular filtration rate (CKD-Epidemiology Collaboration, CKD-EPI) below 30 mL/min; and values ​​of aspartate aminotransaminase (AST) or alanine aminotransaminase (ALT) 5-fold above the upper limit of normality.

Randomization and intervention

A randomization list was developed according to a unique computer-generated number sequence. Randomization was unbalanced in a 1:2:4:2 ratio, and processed in permuted blocks of sizes two, four and six, that were stored in sequentially numbered sealed opaque envelopes that were opened after informed consent at randomization.

Patients randomized to Group SOC received standard of care treatment at the time of hospital admission according to the latest recommendations on managing COVID-19. Patients randomized to receive SOC plus an accumulated dose of ivermectin: 100 mcg/kg; 200 mcg/kg and 400 mcg/kg. Dose reductions, changes in dosage or changes in dosing frequency were not permitted at any time during the study.

Patients were followed for 28 days, with intermediate visits during follow-up days 1 through 7, and returned for follow-up visit 3 weeks after the end of the study dosing period.

SARS-CoV-2 viral load measurements

SARS-CoV-2 RT-PCR and cycle thresholds were performed according to the guidelines set forth by the US Centers for Disease Control and Prevention (CDC) [7]. Undetectable viral load was defined as two consecutive non-detectable SARS-CoV-2 RT-PCR tests. All patients collected daily nasopharyngeal swab specimens until reaching undetectable viral load or completing 7 days of evaluation. Investigators and patients were blinded to the viral load results during the study dosing period.

Safety assessments

During the 28-day follow-up period, patients were monitored for safety at regular intervals from the start of dosing through day 7, and at the follow-up visit 3 weeks after the end of the study drug dosing period. Safety assessments included physical examinations, laboratory tests, and reported adverse events.

Statistical methods

The primary efficacy endpoint was the proportion of patients who achieved undetectable viral load during 7 days of follow-up. The proportion of undetectable viral load was calculated for each group along with their mean changes in cycle threshold values. The study was exploratory and without power to allow comparisons between groups. Therefore, we did not perform any statistical hypothesis tests. Continuous data are presented as mean ± standard deviation or median [1st – 3rd quartile] according to the Shapiro-Wilk test of normality. Categorical variables are presented as counts (percentages). All analyses were conducted with R version 4.0.3 (The R Project for Statistical Computing, 2020).

Results

Patient characteristics

Thirty-two patients were enrolled in the study, one dropped out prior to receiving medication, and one was excluded from the Per Protocol (PP) analysis due to protocol violation (Fig. 1). Baseline characteristics are presented in Table 1.

Fig. 1

Patient flow diagram. Patients with COVID-19 were followed for 28 days, with intermediate visits during follow-up days 1 through 7, and returned for follow-up visit 3 weeks after the end of the study dosing period.

Table 1

The baseline characteristics of the patients.

Feature	Overall (N = 31)	SOC (n = 4)	SOC + Ivermectin 100mcg/kg (n = 6)	SOC + Ivermectin 200mcg/kg (n = 14)	SOC + Ivermectin 400mcg/kg (n = 7)
Age, years	49.4 ± 14.6	54.2 ± 9.6	50 ± 9	49 ± 13.5	47 ± 22.9
Female sex	17 (54.8)	4 (100)	4 (66.7)	5 (35.7)	4 (57.1)
Charlson Comorbidity Index	1 [0–2]	1.5 [0–3]	1.5 [1,2]	0 [0–2]	0 [0–1.5]
Body Mass Index, kg/m [2]	29.1 ± 4.6	33.1 ± 2.7	28.8 ± 2.7	29.9 ± 4.3	25.5 ± 5.4
ECOG score
0	27 (87.1)	3 (75)	5 (83.3)	13 (92.9)	6 (85.7)
1	4 (12.9)	1 (25)	1 (16.7)	1 (7.1)	1 (14.3)
Time from symptom onset to hospital admission, days	8 [7,8,9,10]	9.5 [6.5–10]	7 [6,7,8,9]	8 [7,8,9,10]	9 [6,7,8,9,10]
NEWS2 at hospital admission	1 [0–3]	2 [1.5–3]	2 [0–3]	1.5 [1,2,3]	0 [0–1]
Symptoms
Fatigue	27 (87.1)	4 (100)	5 (83.3)	13 (92.9)	5 (71.4)
Myalgia	22 (71)	2 (50)	4 (66.7)	11 (78.6)	5 (71.4)
Anorexia	21 (67.7)	2 (50)	5 (83.3)	9 (64.3)	5 (71.4)
Anosmia	22 (71)	2 (50)	4 (66.7)	11 (78.6)	5 (71.4)
Cough	20 (64.5)	3 (75)	5 (83.3)	10 (71.4)	2 (28.6)
Dyspnoea	21 (67.7)	3 (75)	4 (66.7)	11 (78.6)	3 (42.9)
Headache	19 (61.3)	4 (100)	4 (66.7)	7 (50)	4 (57.1)
Fever	18 (58.1)	1 (25)	3 (50)	9 (64.3)	5 (71.4)
Ageusia	18 (58.1)	2 (50)	4 (66.7)	9 (64.3)	3 (42.9)
Prescribed medications
Low-molecular-weight heparin
Prophylactic dose	3 (9.7)	0 (0)	1 (16.7)	1 (7.1)	1 (14.3)
Intermediary dose	7 (22.6)	1 (25)	1 (16.7)	5 (35.7)	0 (0)
Therapeutic dose	2 (6.5)	1 (25)	0 (0)	1 (7.1)	0 (0)
Glucocorticoids	10 (32.3)	3 (75)	1 (16.7)	5 (35.7)	1 (14.3)
Antibiotics	9 (29)	3 (75)	1 (16.7)	5 (35.7)	0 (100)

Continuous data are presented as mean ± standard deviation or median [1st - 3rd quartile]. Categorical variables are presented as counts (percentages).

Most of the patients were females (54.8 %) aged 49.4 ± 14.6 years (the youngest patient was 21- and the oldest was 92-years). The median Charlson Comorbidity Index was 1 [1st – 3rd quartile, 0–2], and only one patient (3.2 %) presented high comorbidity (index ≥ 5). The body-mass index was at least 30 kg/m [2] in 48.4 % of the patients and 87.1 % had an ECOG of 0.

The overall median time from symptom onset to hospital admission was 8 [1st – 3rd quartile, 7–10] days. At baseline, most individuals reported fatigue (87.1 %), myalgia (71 %), anosmia (71 %), anorexia (67.7 %), dyspnoea (67.7 %), cough (64.5 %), headache (61.3 %), fever (58.1 %), and ageusia (58.1 %). The mean peripheral oxygen saturation was 95.9 ± 2.5 % (the lowest was 90 %) and 20 % required oxygen supplementation at hospital admission. The median concentration of d-dimer was 0.4 mg per litre (1st – 3rd quartile, 0.2 – 0.61); C-reactive protein, 2.1 mg per decilitre (0.63–8.66); and lactate dehydrogenase, 244 U per litre (189–344). Most of the patients did not receive glucocorticoids (67.7 %), antibiotics (71 %) nor heparin (71 %) during their hospitalization.

SARS-CoV-2 viral load

A total of 30 patients were included in the PP analysis (one patient was excluded due to protocol violation). Between baseline and day 7, all patients showed an increase in cycle threshold value, indicative of decreased viral load. Nineteen patients, 63.3 %, had undetectable levels of SARS-CoV-2 (Ct above 40) within 7 days of the start of study dosing period, with remarkable proportion (71 %) among patients receiving SOC plus ivermectin 200 mcg/kg. Fig. 2 depicts group-wise serial Ct values over 7 days of the start of study dosing period. It is noteworthy that Ct values increased progressively in all patients, but resolved more quickly in the group receiving SOC + ivermectin 200 mcg/kg. Table 2 shows the mean changes in cycle threshold values and the proportion of patients who achieved undetectable viral load for each group during study dosing period. Fig. 3 depicts group-wise median Ct reduction values from day 1–7. In this figure it can be seen that the groups receiving SOC + ivermectin at doses 200 mcg/kg and 400 mcg/kg presented higher Ct reduction values from day 1–7, while SOC alone and SOC + ivermectin 100 mcg/kg presented rather similar results.

Fig. 2

Mean changes in cycle threshold values for (A) Pooled intervention groups (SOC vs Pooled ivermectin), (B) Individual groups during study dosing period.

Table 2

Changes in cycle threshold values and proportion of patients who achieved undetectable viral load for each group during study dosing period.

Feature	SOC (n = 3)	SOC + Ivermectin 100mcg/kg (n = 6)	SOC + Ivermectin 200mcg/kg (n = 14)	SOC + Ivermectin 400mcg/kg (n = 7)	Pooled Ivermectin (n = 27)
Undetectable levels of SARS-CoV-2*	2 (66.7)	3 (50)	10 (71.4)	4 (57.1)	17 (63)
Change in cycle threshold values	11.9 ± 5.58	10.4 ± 5.07	13.9 ± 6.34	9.74 ± 3.81	12.0 ± 5.68
Time to achieve undetectable viral load, days	6 [4.5–6.5]	6 [2,3,4,5,6,7]	5 [4,5,6,7]	5 [4,5,6,7]	5 [3.5–7]

* Defined as defined as two consecutive SARS-CoV-2 RT-PCR tests with negative results (Ct above 40) within 7 days of the start of study dosing period. Continuous data are presented as mean ± standard deviation or median [1st - 3rd quartile]. Categorical variables are presented as counts (percentages).

Fig. 3

Group-wise median cycle threshold reduction values from day 1 to 7.

Safety

A total of 31 patients were included in the safety analysis. Overall, 9 (29 %) patients had at least one adverse event during the study (Table 3). Groups SOC and SOC plus ivermectin 200 mcg/kg had the highest rates of adverse events, accounting for 50 % and 35.7 %, respectively. Overall, a higher relative frequency of adverse events occurred in Group SOC compared to the pooled ivermectin groups (50 % vs 25.9 %, respectively). No individual in either group discontinued treatment because of an adverse event. The most common adverse events were abdominal pain (6.5 %), muscle pains (6.5 %), dizziness (9.7 %), dyspnoea (12.9 %) and cough (12.9 %). All reported adverse events were classified according to their predictability as expected in the natural history of COVID-19 (100 %); of mild (55.5 %) to moderate (44.4 %) severity; unlikely attributable to the intervention (100 %); and that resolved into full recovery by day 21 day of the follow-up (100 %).

Table 3

Summary of adverse events in the safety population.

Feature	SOC (n = 4)	SOC + Ivermectin 100mcg/kg (n = 6)	SOC + Ivermectin 200mcg/kg (n = 14)	SOC + Ivermectin 400mcg/kg (n = 7)	Pooled Ivermectin (n = 27)
Subjects with adverse events
Total	2 (50)	1 (16.7)	5 (35.7)	1 (14.3)	7 (25.9)
Mild	1 (50)	0 (0)	3 (60)	1 (20)	4 (57.2)
Moderate	1 (50)	1 (100)	2 (40)	0 (0)	3 (42.8)
Number of adverse events	2 [0–7.5]	0 [0 – 0]	0 [0–1]	0 [0 – 0]	0 [0 – 0.5]
Adverse events that occurred in 2 or more patients
Gastrointestinal disorders
Abdominal pain	1 (25)	1 (16.7)	0 (0)	0 (0)	1 (3.7)
Neurological disorders
Dizziness	1 (25)	0 (0)	1 (7.1)	1 (14.3)	2 (7.4)
Musculoskeletal and connective tissue disorders
Muscle pains	1 (25)	0 (0)	1 (7.1)	0 (0)	1 (3.7)
Respiratory, thoracic and mediastinal disorders
Cough	2 (50)	0 (0)	2 (14.3)	0 (0)	2 (7.4)
Dyspnoea	2 (50)	0 (0)	2 (14.3)	0 (0)	2 (7.4)
ICU admission for ventilatory support	1 (50)	0 (0)	1 (7.1)	0 (0)	1 (3.7)

Continuous data are presented as median [1st - 3rd quartile]. Categorical variables are presented as counts (percentages).

Discussion

This clinical trial demonstrated the antiviral effects and safety of ivermectin in patients with mild COVID-19. Although it is a pilot study, our results demonstrate that ivermectin treatment with SOC reduces SARS-CoV-2 viral load and the time required to obtain two consecutive negative SARS-CoV-2 RT PCR tests.

All patients showed a reduction in SARS-CoV-2 viral load within 7 days of the start of the dosing period, but those who received ivermectin had a more consistent decrease as compared to the SOC alone group, characterized by a shorter time to obtaining two consecutive negative SARS-CoV-2 RT PCR tests. These findings may have several practical implications, such as the potential to reduce viral shedding, transmissibility, disease severity and mortality [[8], [9], [10]]. Nevertheless, although sixty-three percent of patients who received ivermectin had two consecutive negative SARS-CoV-2 RT PCT within 7 days, these rates varied considerably between the intervention groups, with the lowest rate seen in group SOC + ivermectin 100 mcg/kg (50 %) and the highest in group SOC + ivermectin 200 mcg/kg (71.4 %), whereas in the group SOC + ivermectin 400 mcg/kg the rate was 57 %. Even so, the median Ct reduction from day 1–7 was higher in the groups receiving SOC + ivermectin at doses of 200 mcg/kg and 400 mcg/kg, as compared to SOC alone and SOC + ivermectin 100 mcg/kg, which presented similar results. While this observation may be spurious reflecting an insufficient sample size, it also suggests the presence a linear relationship only seen in the lower dose range with an apparent plateau effect at higher doses.

Recently, a number of caveats have been pointed out regarding the dose of ivermectin necessary to reduce SARS-CoV-2 viral replication. Most of them point out the need for ivermectin at doses 200 times lower than the dose reported by Carly et al. (2020) to promote a reduction in SARS-CoV-2 in vitro viral replication [5,6]. Our results not only corroborate that higher doses have a greater antiviral effect, but also show that supra-lethal toxic doses are unnecessary to inhibit viral replication. Yet, the safety and antiviral benefits of ivermectin doses above 400 mcg/kg in patients with COVID-19 remain unanswered.

In a review on the absorption, distribution, metabolism and excretion of ivermectin in humans, Canga et al. (2008) extensively describe the kinetic parameters of ivermectin after oral administration in healthy subjects, at doses ranging from 6 to 18 mg, as well as 150 mcg/kg [11]. As the authors pointed out, the drug is poorly absorbed, mostly given its extrusion in the gut by the ABCB1/Pgp transporter. Nonetheless, once absorbed, it is widely distributed within the body due to its high lipid solubility. We reference Canga et al., 2008, to direct the curious reader to pertinent information on the pharmacokinetics of ivermectin. It is also noteworthy that ivermectin has shown to exert a strong inhibitory effect of the ABCB1 Pgp transporter along with other ABC transporters (such as ABCG2) located on endothelial cells comprising the blood – brain barrier [12]. Although this may be related to possible neurotoxicity, further studies on the subject are needed, especially with greater doses of ivermectin.

Moreover, although the safety results observed in this trial are consistent with those commonly seen in the natural history of COVID-19, it is noteworthy that associating ivermectin with SOC also reduced symptomatology within 7 days of the start of study dosing period. To this end, in April 2020, Farsalinos et al. hypothesized that the nicotinic cholinergic system maybe implicated in the inflammatory pathophysiology of severe COVID-19, by showing in silico an interaction between SARS-CoV-2 and neuronal nicotinic acetylcholine receptors (nAChRs). Subsequent studies have shown that SARS-CoV-2 may interrupt the cholinergic anti-inflammatory pathway via the interaction of its spike (S) protein with nAChRs, and therefore nicotine agonists could prevent this by restoring the function of these receptors [13,14]. As others have reported, ivermectin has immunomodulatory activity by decreasing the production of several cytokines, such as TNF-α, IL-1, and IL-6 [15,16]. It has also been demonstrated that ivermectin behaves as a positive allosteric effector of the alpha7 neuronal nicotinic acetylcholine receptor (nAChRs alpha7), and therefore, the fewer symptoms reported among those who received ivermectin might be attributed to an ivermectin-induced blunted cytokine response. Additional studies are needed to analyze the impact of ivermectin on cytokine release.

In the past few months there has been a rush for self-medication and self-dosing with ivermectin in several locations around the world, especially in Latin America [17]. Yet, recent studies have shown contrasting results on the clinical benefits of ivermectin in patients with COVID-19. Camprubi et al. (2020) reported that ivermectin did not improve clinical and microbiological outcomes in 13 severe COVID-19 patients receiving immunosuppressant therapy treated with ivermectin at 200 mcg/kg [18]. However, it is noteworthy that in this study the drug was given at late stages of the infection, which may have compromised clinical efficacy and outcomes. On the other hand, Rajter et al. (2020) reported a significantly lower mortality rate in patients who received SOC plus ivermectin at 200 mcg/kg (OR = 0.47; 95 % CI, 0.22−0.99; p < 0.05), and an 11.2 % (95 % CI, 0.38 %–22.1 %) absolute risk reduction [19].

To investigate the efficacy of ivermectin in adult COVID-19 patients with mild symptoms, Ahmed et al. (2021) conducted a randomized, double-blind, placebo-controlled trial. The patients were assigned to one of three groups: oral ivermectin alone (12 mg once daily for 5 days), oral ivermectin in combination with doxycycline (12 mg ivermectin single dose and 200 mg doxycycline on day 1, followed by 100 mg every 12 h for the next 4 days), and a placebo control group. The results showed therapeutic benefit of early intervention with ivermectin alone [20]. A meta-analysis study also supports the effectiveness of ivermectin as add-on therapy in patients with Covid-19, suggesting reduction in mortality and improving clinical outcomes [21]. Recently, a hospital-based matched case-control study among healthcare workers (HCWs) in Bhubaneswar - India, reported on the efficacy of ivermectin as a prophylactic agent against COVID-19 in HCWs [22]. The study showed that two-dose ivermectin prophylaxis, each dose of 300 mcg/kg with a 72 h interval between them, was independently associated with 73 % (Adjusted Odds Ratio 0.27, 95 % Confidence Interval, 0.15−0.51) reduction in SARS-CoV-2 infection among healthcare workers in the following month. Based on these results, a consensus statement was released at the All India Institute of Medical Sciences (AIIMS) recommending that all HCWs receive ivermectin as a prophylactic.

One limitation of our study is the small sample size, which limits the generalizability of the findings. However, the presence of a control group indicates that the beneficial course of the clinical is directly attributable to ivermectin intervention. Further studies should include a larger sample size to adequately detect between-group differences. Another limitation is associated with the time point at which the intervention was evaluated. The literature shows that antivirals exert greater clinical efficacy on when administered early, which was not the approach followed herein. To this end, future studies should consider administering ivermectin early to determine whether it affords greater efficacy on clinical outcomes. Moreover, this was an open-label trial. In general, a blinded trial is considered to be less subject to bias than an open trial, as it minimizes the impact of knowledge of treatment allocation on post-randomized treatment decisions and reporting of results. To this end, we tried to minimize bias by blinding investigators and patients to the viral load results during the study dosing period.

Although the present study is preliminary, the results suggest that administration of ivermectin in patients with SARS-CoV-2 is safe, reducing symptomatology and viral load, thus providing evidence for the potential benefit of early intervention with this drug. Ivermectin’s antiviral effects appear to depend on the administered dose. A larger randomized controlled clinical trial of ivermectin treatment is warranted to validate these important findings. The outbreak of coronavirus disease presents enormous challenges for health, social and economic systems worldwide. If the results of this pilot trial could be further confirmed, ivermectin may be a useful adjuvant to the standard of care treatment for patients with COVID-19, providing a safe and economic tool for coping with the disease.

Funding

This is a non-commercial phase 2a clinical trial conducted at the Federal University of São Carlos, Brazil.

CRediT authorship contribution statement

Henrique Pott-Junior: Conceptualization, Methodology, Data curation, Formal analysis, Writing - original draft, Project administration. Mônica Maria Bastos Paoliello: Writing - review & editing. Alice de Queiroz Constantino Miguel: Investigation. Anderson Ferreira da Cunha: Resources. Caio Cesar de Melo Freire: Resources. Fábio Fernandes Neves: Investigation. Lucimar Retto da Silva de Avó: Resources. Meliza Goi Roscani: Resources. Sigrid De Sousa dos Santos: Investigation. Silvana Gama Florêncio Chachá: Investigation.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.