Efficacy and safety of moxidectin and albendazole compared with ivermectin and albendazole coadministration in adolescents infected with Trichuris trichiura in Tanzania: an open-label, non-inferiority, randomised, controlled, phase 2/3 trial

Pharmacometric Analysis to Describe Pharmacokinetics and Exposure-Efficacy Response of Ivermectin in Adolescents Infected with Trichuris trichiura

The efficacy of the combination therapy of albendazole and ivermectin against Trichuris trichiura infection is higher in Tanzania than in Côte d'Ivoire. This study therefore aimed to investigate the difference between the population pharmacokinetics (PK) at these study sites and to determine if an exposure-response analysis could explain the low efficacy of the combination therapy in Côte d'Ivoire. Twenty-four participants (aged 12-19 years) receiving single doses of ivermectin (200 µg/kg) and albendazole (400 mg) were included in the population PK modeling. A regression analysis was performed to investigate the relationship between the reduction of fecal whipworm eggs and different exposure metrics (peak concentration, area under the plasma drug concentration-time curve [AUC], and time above a certain threshold). The PK profile of ivermectin was best described by a one-compartment model, first-order absorption, and no delay in absorption, with the absorption rate constant estimated as 0.26 per h, an apparent volume of distribution of 162.43 L, and an apparent clearance of 7.82 L/h. In Tanzania, all patients showed a very high reduction in egg count independent of exposure. In Côte d'Ivoire, a relationship was found between higher ivermectin exposure and egg reduction, although not statistically significant. There was no significant difference between the PK profiles at both study sites, despite a difference in clinical outcome. Model-based simulations indicate that higher ivermectin doses such as 400 and 600 µg/kg may be associated with reduced egg count. Larger clinical studies are warranted to explore further the exposure-efficacy response relationship at 200 µg/kg and higher ivermectin doses in adults and children.

Efficacy and safety of ivermectin-albendazole combination versus ivermectin or albendazole monotherapy in soil-transmitted helminthiasis: A systematic review and meta-analysis

BACKGROUND

Soil-transmitted helminthiasis remains a daunting challenge to global health, exerting its greatest toll on resource-limited regions of the world. A dual drug approach using the co-administration of ivermectin and albendazole has shown promising results in comparison to the traditional monotherapy strategy. In light of this, a systematic review and meta-analysis of randomized controlled trials was conducted.

METHODS

Several electronic databases including PubMed, Cochrane Central, Google Scholar, and Embase were explored to search for relevant studies from inception to September 2023. The Cochrane Risk of Bias Tool for Randomized Controlled Studies was utilized to evaluate the quality of studies.

RESULTS

A total of 8 randomized controlled trials, reporting 10 patient populations, were included. The treatment of trichuriasis significantly favored the dual therapy regimen of ivermectin-albendazole over albendazole-only monotherapy (risk ratio [RR]: 2.86; 95% confidence interval [CI]: 1.66-4.93; P = .0002), with no significant differences observed for ascariasis and hookworm. The treatment of trichuriasis and hookworm significantly favored the dual therapy regimen of ivermectin-albendazole over ivermectin-only monotherapy (RR: 1.86; 95% CI: 1.56-2.21; P < .00001 and RR: 2.31; 95% CI: 1.23-4.31; P = .009, respectively). There were no statistically significant differences between dual therapy and monotherapy in terms of adverse effects.

CONCLUSION

These findings highlight the nuanced effectiveness of combined therapy specific to certain helminth types, in addition to their comparable safety profiles, thereby providing pivotal insights that contribute to the evolving landscape of soil-transmitted helminth treatment strategies.

Deep-amplicon sequencing of the complete beta-tubulin gene in Trichuris trichiura before and after albendazole treatment

Concerns about the emergence of benzimidazole resistance in soil-transmitted helminths (STH) infections, particularly against Trichuris trichiura, have arisen. Previous studies of veterinary nematodes have linked benzimidazole resistance to single-nucleotide polymorphisms (SNPs) at three specific codons in the beta-tubulin gene, but similar associations in STH have not been consistently observed. In this work, we screened the complete beta-tubulin gene previously linked to benzimidazole resistance in T. trichiura by deep-amplicon sequencing to identify genetic variants and associate levels of diversity with drug response to albendazole. We used 99 DNA samples extracted from T. trichiura pooled eggs, previously semi-purified from human stool samples collected in Manhiça district, Mozambique. We obtained a set of 39 amplicons of the complete gene by subjecting the pooled eggs to long-read PCR and subsequently sequencing them. Of those amplicons, 22 and 17 were obtained from stool samples collected before, and 21 days after albendazole treatment, respectively. We observed genetic variation across the whole gene sequence, in both exons and introns; however, none were associated with the previously proposed resistance-associated SNPs, and none were predicted to significantly affect protein function. No significant differences in genetic diversity were observed between pre- and post-treatment samples. Using publicly available genome-wide data, we also analysed a second beta-tubulin isotype in the T. trichiura genome. We focused on detecting the canonical SNPs and assessing for signatures of genetic selection around this second isotype gene. This analysis did not reveal evidence supporting this second isotype's role in anthelmintic resistance. Despite the limitations of our study, such as a small sample size, particularly paired pre- and post-treatment samples (n = 6), or a restricted geographical area, we found no evidence linking either of the two beta-tubulin genes to benzimidazole resistance in T. trichiura, suggesting that genetic markers of drug resistance likely exist outside the beta-tubulin genes.

Moxidectin versus Ivermectin in the prevention and treatment of acute and chronic experimental trichinellosis

The limited activity of the traditional medications against T. spiralis encysted larvae handicaps complete cure of trichinellosis till now due to decreased permeability and absorption through tissues. MOX is listed worldwide for prevention and treatment of several internal and external nematodes. Consequently, the aim of this work was to investigate the effect of moxidectin versus ivermectin on experimental acute and chronic trichinellosis and to illuminate the potential mechanisms of their effects. 105 Mice were divided into four groups; Group I: Uninfected healthy control; Group II: Infected untreated control; Group III: Infected and treated with IVM and Group IV: Infected and treated with MOX. The groups (II, III and IV) were later subdivided equally into three subgroups (a, b, and c) according to the stage of treatment. Parasitological counting of adults and larvae besides immune-histopathological examination of intestines and muscles were done. Results exhibited that both IVM and MOX succeeded in reducing adults and larvae counts with higher potential of MOX in both intestinal and muscle phase. The preeminence of MOX was indicated by decreased inflammation, a significant reduction in the microvascular density (CD31 immunostaining) as well as a reduction in the percentage of fibroblast activation protein (FAP) immunostaining in muscle tissues. Accordingly, the current work recommends moxidectin as an innovative treatment for trichinellosis.

Understanding Drug Exposure and Trichuris trichiura Cure Rates: A Pharmacometric Approach for Albendazole-Ivermectin Co-medication in Tanzania and Côte d'Ivoire

BACKGROUND AND OBJECTIVE

Trichuriasis caused by the human whipworm Trichuris trichiura poses a significant public health concern. Albendazole-ivermectin co-medication is currently the most effective treatment. Studies conducted in Tanzania and Côte d'Ivoire unveiled differences in efficacy for albendazole-ivermectin combination therapy in both countries. A pharmacometrics approach was used to assess co-medication and study population effects on the pharmacokinetics of the two main metabolites of albendazole. An exploratory exposure-efficacy analysis was also carried out to investigate relationships between exposure measures and the egg reduction rate.

METHODS

Pharmacokinetic data from studies in Tanzania and Côte d'Ivoire in adolescents (aged 12-19 years) were included in the pharmacometric analysis. Participants received a single dose of either albendazole 400 mg alone or in combination with ivermectin 200 µg/kg. A pharmacometric analysis was performed to investigate the potential effects of the study population and co-administered ivermectin on the apparent clearance of the metabolites of albendazole. Non-linear mixed-effects modeling was conducted with MonolixSuite 2023R1. The pharmacokinetic exposure measures derived from simulations with individual model parameters were used in the exploratory-exposure response analysis.

RESULTS

Pharmacokinetic profiles were best described by a two-compartment model for albendazole sulfoxide and a one-compartment model for albendazole sulfone, with a transit compartment and linear elimination. While no co-medication effect was found, apparent clearance of albendazole sulfoxide (albendazole sulfone) in the Tanzanian study population was 75% (46%) higher than that in the Côte d'Ivoire study population. Exposure-efficacy response analyses indicated that peak concentration and the time-above-exposure threshold were associated with the egg reduction rate.

CONCLUSIONS

Study population but not co-administered ivermectin showed an effect on apparent clearance of albendazole sulfoxide and albendazole sulfone. Polymorphisms in drug-metabolizing enzymes and host-parasite interaction may explain this result. Difference in drug exposure did not explain the disparate efficacy responses in Tanzania and Côte d'Ivoire. Peak concentration and time-above-threshold were exposure measures associated with the egg reduction rate. Further studies evaluating genetic and resistance patterns in various regions in Africa are warranted.

Efficacy and safety of moxidectin compared with ivermectin against Strongyloides stercoralis infection in adults in Laos and Cambodia: a randomised, double-blind, non-inferiority, phase 2b/3 trial

BACKGROUND

Infection with the soil-transmitted helminth Strongyloides stercoralis affects up to 600 million people globally, most of whom live in rural areas with poor sanitation. If untreated, infection leads to long-lasting morbidity and might even be life-threatening. Moxidectin might be a promising alternative to ivermectin, the only currently recommended single-dose treatment. We aimed to assess whether moxidectin is non-inferior in terms of efficacy and safety compared with ivermectin.

METHODS

In this randomised, double-blind, parallel-group, non-inferiority, phase 2b/3 trial in communities in Laos and Cambodia, adults aged 18-65 years were screened for the presence of S stercoralis larvae in their stool via sextuplicate quantitative Baermann assays. Using computer-generated group allocation (block randomisation stratified by infection intensity), parasitologically (two or more positive Baermann assays) and clinically eligible participants were randomly assigned (1:1) to receive single oral doses of either moxidectin (8 mg) and ivermectin-matched placebo, or ivermectin (200 μg/kg bodyweight) and moxidectin-matched placebo. The primary endpoint was cure rate assessed at 14-21 days after treatment, using the available-case population analysed according to intention-to-treat principles. Moxidectin was considered non-inferior to ivermectin if the lower limit of the two-sided 95% CI of the difference was greater than the non-inferiority margin of -10 percentage points. Safety endpoints were assessed before treatment, and at 2-3 h, 24 h, and 14-21 days after treatment. This trial is registered at ClinicalTrials.gov, NCT04056325 and NCT04848688.

FINDINGS

Between Dec 6, 2020, and May 21, 2022, 4291 participants were screened, 726 of whom were enrolled and randomly assigned to moxidectin (n=363) or ivermectin (n=363). For the participants with primary outcome data, we observed a cure rate of 93·6% (95% CI 90·5 to 96·0; 324 of 346 participants) in the moxidectin group and 95·7% (93·0 to 97·6; 335 of 350 participants) in the ivermectin group, resulting in a between-group difference of -2·1 percentage points (95% CI -5·5 to 1·3). The most common adverse events were abdominal pain (32 [9%] of 363 with moxidectin vs 34 [9%] of 363 with ivermectin) and headache (25 [7%] vs 30 [8%]), which were predominantly mild and transient.

INTERPRETATION

Moxidectin was non-inferior to ivermectin in terms of efficacy in the treatment of strongyloidiasis. Additionally, both drugs had a similar safety profile. The fixed dose and lower cost of moxidectin compared with ivermectin make it a valuable alternative for people with strongyloidiasis.

FUNDING

Swiss National Science Foundation.

Antiparasitic activity of ivermectin: Four decades of research into a "wonder drug"

Parasitic diseases still pose a serious threat to human and animal health, particularly for millions of people and their livelihoods in low-income countries. Therefore, research into the development of effective antiparasitic drugs remains a priority. Ivermectin, a sixteen-membered macrocyclic lactone, exhibits a broad spectrum of antiparasitic activities, which, combined with its low toxicity, has allowed the drug to be widely used in the treatment of parasitic diseases affecting humans and animals. In addition to its licensed use against river blindness and strongyloidiasis in humans, and against roundworm and arthropod infestations in animals, ivermectin is also used "off-label" to treat many other worm-related parasitic diseases, particularly in domestic animals. In addition, several experimental studies indicate that ivermectin displays also potent activity against viruses, bacteria, protozoans, trematodes, and insects. This review article summarizes the last 40 years of research on the antiparasitic effects of ivermectin, and the use of the drug in the treatment of parasitic diseases in humans and animals.

Efficacy and Safety of Moxidectin-Albendazole and Ivermectin-Albendazole Combination Therapy Compared to Albendazole Monotherapy in Adolescents and Adults Infected with Trichuris trichiura: A Randomized, Controlled Superiority Trial

BACKGROUND

The currently recommended benzimidazole monotherapy is insufficiently effective to control infection with the soil-transmitted helminth Trichuris trichiura. Ivermectin-albendazole combination has shown promising, but setting-dependent efficacy, with therapeutic underperformance in Côte d'Ivoire. We evaluated whether moxidectin-albendazole could serve as an alternative to albendazole monotherapy in Côte d'Ivoire.

METHODS

In this community-based, randomized, placebo-controlled, parallel-group superiority trial, individuals aged 12-60 years were screened for T. trichiura eggs in their stool using quadruplicate Kato-Katz thick smears. Diagnostically and clinically eligible participants were randomly assigned (1:1:1) to receive single oral doses of moxidectin (8 mg) and albendazole (400 mg), ivermectin (200 µg/kg) and albendazole (400 mg), or albendazole (400 mg) and placebo. The primary outcome was proportion cured, ie, cure rate (CR), assessed at 2-3 weeks post-treatment. Safety endpoints were assessed pre-treatment and at 3 and 24 hours post-treatment.

RESULTS

For the 210 participants with primary outcome data, we observed CRs of 15.3% in the moxidectin-albendazole arm and 22.5% in the ivermectin-albendazole arm, which did not differ significantly from the CR of 13.4% in the albendazole arm (differences: 1.8%-points [95% confidence interval: -10.1 to 13.6] and 9.1%-points [-3.9 to 21.8], respectively). Most common adverse events were abdominal pain (range across arms: 11.9%-20.9%), headache (4.7%-14.3%), and itching (5.8%-13.1%), which were predominantly mild and transient.

CONCLUSIONS

All therapies showed similar low efficacy in treating trichuriasis in Côte d'Ivoire. Alternative treatment options need to be evaluated, and further analyses should be conducted to understand the lack of enhanced activity of the combination therapies in Côte d'Ivoire.

CLINICAL TRIALS REGISTRATION

NCT04726969.

Safety and tolerability of moxidectin and ivermectin combination treatments for lymphatic filariasis in Côte d'Ivoire: A randomized controlled superiority study

BACKGROUND

Moxidectin is a macrocyclic lactone registered for the treatment of human onchocerciasis. The drug has a good safety profile, large volume of distribution and a long elimination half-life. This paper reports tolerability data from the first use of moxidectin in persons with Wuchereria bancrofti infection.

METHODS

In this randomized, open-label, masked-observer superiority trial, adults with Wuchereria bancrofti microfilaremia in Côte d'Ivoire were randomized to 1 of 4 treatment arms: ivermectin + albendazole (IA), moxidectin + albendazole (MoxA), ivermectin + diethylcarbamazine (DEC) + albendazole (IDA), or moxidectin + DEC + albendazole (MoxDA). As part of a larger efficacy trial, all participants were closely monitored for 7 days after treatment.

RESULTS

One hundred sixty-four individuals were treated, and monitored for treatment emergent adverse events (TEAE). Eighty-seven participants (53%) experienced one or more mild (grade 1) or moderate (grade 2) TEAE. Four participants had transient Grade 3 hematuria after treatment (3 after IDA and 1 after IA). There were no serious adverse events. There were no significant differences in frequency or types of TEAE between treatment groups (IA = 22/41 (53%), MoxA = 24/40 (60%), IDA = 18/41 (44%), MoxDA = 15/42 (36%), p = 0.530). Fifty-nine participants (36%) had multiple TEAE, and 8.5% had a one or more grade 2 (moderate) TEAE. Grade 2 TEAE were more frequent after triple drug treatments (IDA, 14.6%; MoxDA, 9.5%) than after two-drug treatments (IA, 7.3%; MoxA, 2.5%). There was no difference in TEAEs based on baseline Mf counts (OR 0.69 (0.33, 1.43), p-value 0.319).

CONCLUSION

All treatment regimens were well tolerated. We observed no difference in safety parameters between regimens that contained ivermectin or moxidectin.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT04410406.

Ivermectin and moxidectin against soil-transmitted helminth infections

Ivermectin and moxidectin, two macrocyclic lactones, are potent antiparasitic drugs currently registered and mainly used against filarial diseases; however, their potential value for improved soil-transmitted helminth (STH) control has been acknowledged. This review provides insights on recent studies evaluating the efficacy of ivermectin and moxidectin as single or coadministered therapy against human soil-transmitted helminthiases (including Strongyloides stercoralis infections) and on pharmacokinetic/pharmacodynamic parameters measured in treated populations. Furthermore, we discuss current gaps for research, highlight advantages - but also existing challenges - for uptake of ivermectin and/or moxidectin treatment schemes into routine STH control in endemic countries.