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Randomized Controlled Trial
. 2022 Aug 24;75(1):19-27.
doi: 10.1093/cid/ciab906.

Safety and Efficacy of Levamisole in Loiasis: A Randomized, Placebo-controlled, Double-blind Clinical Trial

Jérémy T Campillo  1 , Paul Bikita  2 , Marlhand Hemilembolo  2 , Frédéric Louya  2 , François Missamou  2 , Sébastien D S Pion  1 , Michel Boussinesq  1 , CédricB Chesnais  1
Affiliations
Randomized Controlled Trial

Safety and Efficacy of Levamisole in Loiasis: A Randomized, Placebo-controlled, Double-blind Clinical Trial

Jérémy T Campillo et al. Clin Infect Dis. .

Abstract

Background: Individuals with high microfilarial densities (MFDs) of Loa loa are at risk of developing serious adverse events (SAEs) after ivermectin treatment. Pretreatment with drugs progressively reducing Loa MFDs below the risk threshold might help prevent these SAEs. We assessed the safety and efficacy of levamisole for this purpose.

Methods: A double-blind, randomized, placebo-controlled, MFD-ascending trial was conducted in the Republic of the Congo. Participants were treated in 3 cohorts defined by pretreatment MFD and levamisole dose (cohort 1: 1.0kg and 1.5mg/kg; cohorts 2 and 3: 2.5mg/kg). Safety outcomes were occurrence of SAE and adverse event frequency during the first week. The efficacy outcomes were MFD reduction from baseline and proportions of individuals with at least 40% and 80% MFD reduction at day 2 (D2), D7, and D30.

Results: The 2 lowest doses (1.0mg/kg and 1.5mg/kg) caused no SAEs but were ineffective. Compared with placebo, 2.5mg/kg levamisole caused more mild adverse events (10/85 vs. 3/85, P=.018), a higher median reduction from baseline to D2 (-12.9% vs. +15.5%, P<.001), D7 (-4.9% vs. +18.7%, P<.001), and D30 (-0.5% vs. +13.5%, P=.036) and a higher percentage of participants with >40% MFD reduction at D2 (17.5% vs. 1.2%, P<.001), D7 (11.8% vs. 6.3%, P=.269), and D30 (18.5% vs. 9.6%, P=.107).

Conclusions: A single 2.5mg/kg levamisole dose induces a promising transient reduction in Loa loa MFDs and should encourage testing different regimens.

Trial registration: ClinicalTrials.gov NCT04049630.

Keywords: Africa; clinical trial; filariasis; levamisole; loiasis.

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Figures

Figure 1.
Figure 1.
Flowchart of the clinical trial. Abbreviations: LEV, levamisole; MFD, microfilarial density.
Figure 2.
Figure 2.
Evolution of mean and median microfilarial densities. A, arithmetic mean with 95% confidence interval; (B) median with interquartile range; (C) geometric mean with 95% confidence interval.
Figure 3.
Figure 3.
Evolution of individual microfilarial densities. Abbreviation: LEV, levamisole.
See this image and copyright information in PMC

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