COVID-19 disease caused by SARS CoV-2 causes severe viral pneumonia at rates varying between 7 and 14.8%, especially in some patients in the risk group. Its mortality is reported to be between 2 and 4%. Unfortunately, there are no proven treatments for patients with COVID-19 disease but drugs with antiviral, anti-inflammatory and immunomodulatory properties that are currently used in the treatment of COVID-19 [3, 10,11,12,13,14].
Advanced age (> 65), hypertension (HT) or the presence of coronary heart disease, diabetes mellitus (DM) and male gender are risk factors that have been shown to be associated with severe prognosis [12, 14, 15]. In accordance with the literature, the three most common comorbid conditions in severe COVID-19 patients were identified as HT, DM, and coronary artery disease in our study (Table 1). In our study, although hypertension was more common in the study group than in the control group, other comorbidities were higher in the control group. But we did not think that this difference would have a negative effect on the study results because it was not statistically significant. Our study is the first prospective randomized controlled trial investigating the efficacy of ivermectin in the treatment of patients with severe COVID-19.
In the literature, there are a few prospective randomized controlled studies evaluating the efficacy of hydroxychloroquine, lopinavir-ritonavir, remdesivir, and favipiravir drugs, which are among the treatment options of COVID-19 patients [16,17,18,19]. When these studies were examined, it was reported that remdesivir shortened the recovery time compared to placebo, and favipiravir increased viral clearance [18, 19].
In our study, we found that patients who added ivermectin to the HFA combination therapy (study group) had a higher rate of clinical improvement compared to patients who received only HFA combination therapy (control group). Similarly, at the end of the follow-up period, mortality rates were found to be lower in the study group, compared to the control group receiving only HFA combination therapy. Although clinical improvement and mortality differences between study and control group were not statistically significant, these differences can be more clearly revealed in new studies including larger patient series.
Considering that the patients included in our study have severe COVID-19, it can be thought that we have achieved a better clinical response with ivermectin treatment than the antiviral drugs studied so far. In a retrospective cohort analysis conducted in Florida, it was reported that mortality was reduced in COVID-19 patients with the use of a single dose of ivermectin, supporting our results . Yet our results suggest that ivermectin may be an alternative or an additional option to standart treatment protocols in the treatment of COVID-19 disease.
SpO2 are below physiological levels in most patients who develop COVID-19 pneumonia and in all patients with severe prognosis. Also SpO2 levels cannot reach normal limits most of the time despite oxygen support or other supportive treatments in patients with severe prognosis. Increase in SpO2 level with treatment in patients is a significant indicator of clinical response to treatment [21, 22]. In our study, SpO2 levels increased compared to the baseline levels in both groups during the treatment and follow-up period, but reached the desired levels in the study group at the end of the follow-up period (95.4%) and were found to be significantly higher than the control group. Accordingly, it can be said that adding ivermectin to the treatment has a more positive effect on the treatment of Covid-19 pneumonia than the current treatment protocol.
As a matter of fact, in a study comparing the efficacy of single dose ivermectin + doxycycline combination and azithromycin + hydroxychloroquine combination therapies in patients with mild to moderate severity COVID-19, it was reported that symptomatic improvement was achieved in a shorter time with the combination containing ivermectin .
The best indicator of oxygenation in the blood is the PaO2/FiO2 ratio. Its normal range is 300–500 mmHg and being < 200 mmHg indicates severe hypoxemia. An increase in this rate indicates clinical improvement in severe COVID-19 patients . We created the research universe from patients with severe COVID-19 at high mortality risk. Although the initial PaO2/FiO2 ratios of the patients in the study group were lower than the control group and there was a slight decrease at the beginning of the treatment period, the fact that they reached the higher values at the end of the treatment and follow-up period compared to the baseline levels and control group can be evaluated as an indicator of the effectiveness of adding ivermectin to the treatment. The fact that adequate response at PaO2/FiO2 ratios was obtained in the late periods of the study, suggests that more positive results can be obtained by starting ivermectin treatment earlier before severe pneumonia develops. The suggestion that ivermectin can be used in patients with mild or moderate COVID-19 pneumonia should be supported by further studies.
In COVID-19 disease, serum ferritin, CRP and D-dimer levels, blood lymphocyte count, and PNL/L ratio are laboratory parameters that have been shown to be associated with prognosis. It is reported that the prognosis is worse especially in patients whose lymphocyte count does not change despite the treatments given and whose ferritin and D-dimer values remain high. Therefore, changes in these parameters are considered as substantial indicators of clinical response in patients receiving treatment [25,26,27,28].
In our study, with the addition of ivermectin to the treatment, it was observed that a more pronounced and earlier increase in lymphocyte counts was achieved in patients in the study group compared to the control group. While PNL/L ratio, one of the prognosis indicators, started to decrease early in the treatment period in the study group, it increased in the control group. In the study group, this decrease continued significantly in the follow-up period. But in the control group, a decrease in the PNL/L ratio was observed only towards the middle of the follow-up period. This result shows that ivermectin provides earlier treatment efficacy in the treatment of COVID-19 infection compared to existing protocols.
In the literature, it has been reported that the prognosis will be poor in patients > 50 years of age and with PNL/L > 3.13 and intensive care follow-up is required . Therefore, the early decrease provided by ivermectin in PNL/L ratios can contribute to shortening the intensive care period and improving the prognosis in COVID-19 infections. At the end of the follow-up period, it was observed that PNL/L ratios were lower in both groups compared to the baseline values, the decrease in the study group was more pronounced than the control group, but there was no significant difference between both groups. While the decrease in the PNL/L ratio continued significantly in the study group until the 3rd day in the follow-up period, there was a slight increase on the 5th day. The reason for this may be leukocytosis due to secondary bacterial infections (unspecified data) that we detected in patients.
The fact that serum CRP and D-dimer values decreased significantly earlier and faster in the study group, and serum ferritin values decreased significantly in the study group while continued to increased in the control group, can be considered as an indicator that adding ivermectin increases the effectiveness of the severe Covid-19 infection treatment.
When the results of these five laboratory parameters which are valuable in the follow-up of the prognosis of the disease (blood lymphocyte count, serum ferritin, CRP, D-dimer levels and PNL/L ratio) were evaluated; it was found that ivermectin was effective in the treatment of COVID-19, it seems to provide an earlier treatment response and supports the idea that ivermectin or adding ivermectin to current treatment protocols may be an option for the treatment of COVID-19.
In our study, no different side effects were observed in patients receiving ivermectin compared to patients receiving standard therapy. However, three of the 6 patients with MDR-1/ABCB1 or CYP3A4 gene mutation who received the first dose of ivermectin had mild (agitation) and two had severe side effects (agitation, delirium-like behavior, aggressive behavior and consciousness changes).
The determination of ABCB1 (NM_000927.4)1236 T > C/2677 T > G/3435 T > C genotypes is important in determining the risk of side effects in drug use. ABCB1 (NM_000927.4)1236 T > C/2677 T > G/3435 T > C genotype was detected in all 6 patients who excluded from the study. Therefore, this haplotype including in cases where it is heterozygous, was considered as the main haplotype in terms of complication development, and at the end of the study it was determined that this prediction was mostly correct.
In one of these 6 patients, S400I (c.1199G > A), CM068130, rs2229109 genotype were found in addition to ABCB1 gene. Although it has been stated in the literature that the S400I change may alter membrane transport and cause drug resistance (PMID: 16917872), no side effects related to ivermectin developed in this patient.
ABCB1 (NM_001348945.1): c.210G > A(p.Gly70 =) genotype was additionally found in two of our 3 patients with mild side effects. On the other hand, the detection of the same genotype in 2 of 31 patients without side effects suggests that this genotype change has no effect on ivermectin metabolism.
In our patient, who developed the most severe and longest lasting side effect associated with ivermectin, in addition to ABCB1 mutation, a change in CYP3A4 gene was found to be c.1191C > T(p.T363M). It has been reported in the literature that the T363M change detected in the CYP3A4 gene reduces the function of the enzyme. Therefore, it has been recommended in the literature to reduce the drug dose (HGMD: CM015322). After the first dose of ivermectin, agitation, delirium-like symptoms, aggression and changes in consciousness were observed in this patient who was given remifentanyl and dexmedetomidine for sedation and was excluded from the study. Midazolam administration was also required and it took about 2 weeks for symptoms to disappear in this patient. The reason for the longer and more severe clinical symptoms in this patient compared to the patients with other drug side effects was considered to be the coexistence of both ABCB1 and CYP3A4 changes. This finding suggests that the CYP3A4 gene is also effective and important in ivermectin metabolism.
In our study, in patients who developed side effects due to ivermectin, symptoms disappeared completely within 2 weeks in 2 patients with severe side effects and in 1–2 days in 3 patients with mild side effects. All these results suggest that, the drug can be used safely in patients who do not have a mutation that may affect ivermectin metabolism. If it is decided to use drug at the community level or in large groups, since sequence analysis is not possible in practice due to time constraints, patients should be followed up closely in terms of encephalopathy-like symptoms affecting the central nervous system, and symptoms can be controlled in these patients with appropriate treatment and follow-up.
Our study is the first randomized controlled prospective study in the literature in which MDR-1/ABCB1 and CYP3A4 gene variants that may cause changes in ivermectin dose were investigated in patients with COVID-19. There are warnings in the literature as the study of Caly et al., about the possible toxic effects of Ivermectin that is a promising drug for the treatment of COVID-19 and the FDA also draws particular attention to this issue [7, 29]. However, our result sheds light on the concerns in this regard.
One limitation of our study is that the interactions of the drugs used were not evaluated. However, we think that there is no adverse drug interaction due to the absence of any laboratory changes that cannot be explained with the clinical conditions of the patients .