Due to the pandemic of COVID-19 and the lack of effective treatment, many efforts are being made to find a regimen to improve patients' clinical outcomes. Recently, IVE/DOXY combination has been proposed by a couple of studies in treatment of COVID-19. To the best of our knowledge, this is the first meta-analysis investigating the effect of the IVE/DOXY combination on clinical outcomes of patients with COVID-19.
Doxycycline is an antibiotic which can be used to treat atypical bacterial pneumonia and community-acquired pneumonia (39). In mammalian cells, doxycycline has an anti-inflammatory action that is mediated by chelating zinc compounds on matrix metalloproteinases (MMPs) (40). Murine coronaviruses rely on MMPs for cell fusion and viral multiplication, according to prior in vitro research (41). COVID-19's pathologic characteristics are similar to those of previous SARS-CoV infections, in which MMPs play a key role in disease development (42). Doxycycline's pharmacokinetics indicate that it is dispersed in pulmonary tissue following oral administration, with the drug's concentration in the lungs being 18–23% of the serum concentration in humans (43). As a result, doxycycline might be useful in the treatment of COVID-19 infection.
Ivermectin is a well-known antiparasitic medication that is used to treat a variety of parasites all over the world. A meta-analysis demonstrated that ivermectin can not only reduce the number of COVID-19 deaths, but also lead to significant reduction in the number of progressive disease cases if started in early clinical course (8). In preclinical models of numerous additional diseases, ivermectin has exhibited immunomodulatory and anti-inflammatory functions. Ivermectin has been shown to inhibit the synthesis of inflammatory mediators such as nitric oxide and prostaglandin E2 in vitro studies (44). In mice given a fatal dosage of lipopolysaccharide, Ivermectin decreased TNF-α, IL-1, and IL-6, and increased survival (45). Subcutaneous ivermectin reduced the IL-6/IL-10 ratio in the lung tissues of Syrian golden hamsters infected with SARS-CoV-2 and prevented clinical deterioration (46). Ivermectin's antiviral activity against SARS-CoV-2 in Vero/hSLAM cells has been proven. However, after oral administration of the medication to patients, the concentrations necessary to suppress viral multiplication in vitro (EC50 = 2.8µM; EC90 = 4.4µM) are not attained systemically (22, 47). Although the standard dose of a single 200µg/kg oral of ivermectin for treating strongyloidiasis is thought to accumulate in lung tissues (2.67 times that in plasma), there is no evidence that this dosage regimen would result in ivermectin reaching an antiviral concentration in the lungs (48, 49). As a result, alternative administration methods for ivermectin in COVID-19 should be considered, such as utilizing in combination with medicines that increase ivermectin activity through mechanisms such as increasing ivermectin pulmonary penetration (50). Therefore, we aim to perform a systematic review and meta-analysis to determine the efficacy of the IVE/DOXY combination in COVID-19 therapy.
Based on a meta-analysis of five related studies, the combination of IVE/DOXY significantly reduced the time to clinical recovery. Although the mortality rate was lower in the IVE/DOXY group than in the control group, there was no significant difference. The IVE/DOXY group had a shorter period of time to a negative PCR than the control group. The difference, however, was not statistically significant. Co-administration of ivermectin and doxycycline did not differ in the length of hospital stay.
These findings, however, should be taken with caution. It must be considered that the low mortality rate which was reported in just two studies is due to that majority of enrolled patients were inclined to mild to moderate. On the other hand, in the Hashim et al. (37) study, no critical patients were included in the control group. In the Mahmud et al. (36) study, the number of patients with at least one comorbidity and the tendency of mild patients to be in the IVE/DOXY group was lower. The three patients who died in the control group had a higher mean age than the others (63 years vs. 39 years). Furthermore, both studies assessing hospital stay (27, 38) were of poor quality.
Three studies in this meta-analysis reported adverse events in patients administered IVE/DOXY. Serious adverse drug reactions with the use of IVE/DOXY, though uncommon, have been reported. In the study by Mahmud et al. (36) adverse drug reactions occurred in 9 patients (2.5%); Two of them showed signs of erosive esophagitis and 7 developed non-ulcer dyspepsia.In the study by Spoorthi et al. (38) 11% (7/62) in the IVE/DOXY group and 6.6% (4/60) in the control group experienced gastrointestinal disturbances. One patient in the treatment group experienced pruritus. In the report by Chowdhury et.al (29) the most common adverse events included lethargy in 14 (23.3%), nausea in 11 (18.3%), and occasional vertigo in 7 (11.66%) patients in the IVE/DOXY group.
Although the methodological quality of all studies was medium to low, study's limitations must be taken into account. There were few trials and limited patients, and adverse events were not reported in the majority of the studies. Thus, further large-scale randomized controlled studies are required to clarify the findings.