Efficacy and Safety of Ascending Doses of Arpraziquantel in Children Infected With Opisthorchis Viverrini (ADORA-VI)

Efficacy, Safety and Acceptability of Ascending Doses of Arpraziquantel for Opisthorchis Viverrini Infections in Children Aged 6-7 Years: A Single-blind Randomized Dose-ranging Trial

This study aims to assess the efficacy, safety and acceptability of ascending doses of arpraziquantel in children infected with Opisthorchis viverrini. The primary objective is to determine the dose-response relationship in terms of cure rate. This study will involve children aged 6-7 years, since O. viverrini infections often occur in pre-school and school-aged children, and this group is largely left untreated in current public health programs.

Study Overview

• Status: Not yet recruiting
• Conditions: Opisthorchis Viverrini
• Intervention / Treatment: Drug: Apraziquantel

• Study Type: Interventional
• Enrollment (Estimated): 125
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Jennifer Keiser, PhD; Phone Number: +41 61 284 82 18; Email: jennifer.keiser@swisstph.ch

Study Locations

• Laos
  • Vientiane, Laos
    • Lao Tropical and Public Health Institute (Lao TPHI)
    • Contact: Somphou Sayasone, PhD; Phone Number: +856 20 556 79 603; Email: somphou.sayasone@yahoo.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Aged 6 to 7 years (i.e., 72 to 95 months).
• Written informed consent signed by parents/caregivers (signature or thumbprint).
• Agree to comply with study procedures, including provision of two stool samples at baseline and at follow-up assessment 21-28 days after treatment, respectively.
• Willing to be examined by a study physician prior to treatment.
• At least two slides of the quadruple Kato-Katz thick smears positive for O. viverrini.

Exclusion Criteria:

• Presence or signs of major systemic illness, e.g. severe anaemia (haemoglobin level of < 80 g/L according to WHO) upon initial clinical assessment.
• Known or suspected infection with Taenia solium (cysticercosis).
• Known or suspected acute schistosomiasis.
• Abnormal liver and kidney function.
• Use of anthelminthic drugs within 4 weeks before or during study period.
• Known allergy to study medications (i.e. praziquantel or any of the excipients).
• Being prescribed or taking concomitantly medication with known contraindication or drug interactions with the study medication.
• Concurrent participation in other clinical trials.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Arpraziquantel 30 mg/kg; Treatment with a single dose arpraziquantel: 30 mg/kg, orally administered	Drug: Apraziquantel; Tablets (dispersible) containing 150 mg arpraziquantel
Experimental: Arpraziquantel 40 mg/kg; Treatment with a single dose arpraziquantel: 40 mg/kg, orally administered	Drug: Apraziquantel; Tablets (dispersible) containing 150 mg arpraziquantel
Experimental: Arpraziquantel 50 mg/kg; Treatment with a single dose arpraziquantel: 50 mg/kg, orally administered	Drug: Apraziquantel; Tablets (dispersible) containing 150 mg arpraziquantel
Experimental: Arpraziquantel 60 mg/kg; Treatment with a single dose arpraziquantel: 60 mg/kg, orally administered	Drug: Apraziquantel; Tablets (dispersible) containing 150 mg arpraziquantel
Experimental: Arpraziquantel 20 mg/kg; Treatment with a single dose arpraziquantel: 20 mg/kg, orally administered	Drug: Apraziquantel; Tablets (dispersible) containing 150 mg arpraziquantel

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cure rate (CR) of arpraziquantel against O. viverrini	CRs will be calculated as the percentage of O. viverrini egg-positive participants at baseline who become egg-negative after treatment.	21-28 days after treatment

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Egg reduction rates (ERR) of arpraziquantel against O. viverrini	Eggs per gram of stool (EPG) will be assessed by calculating the mean egg counts from the quadruplicate Kato-Katz thick smears and multiplying this number by a factor of 24. Geometric and arithmetic mean egg counts will be calculated for the different treatment arms before and after treatment to assess the corresponding ERRs.	21-28 days after treatment
Safety and tolerability of the different arpraziquantel dosing regimens, and compared to placebo	Participants will be monitored at the site for 3 hours following treatment for any acute adverse events (AEs). Participants will be interviewed 3 hours and 24 hours after treatment, as well as 21-28 days and 42 days after treatment administration about the occurrence of AEs. AEs will be evaluated descriptively as the difference of proportion reported AEs before and after treatment.	3 hours, 24 hours, 21-28 days and 42 days after treatment

Collaborators and Investigators

• Sponsor: Jennifer Keiser
• Collaborators: Lao Tropical and Public Health Institute (Lao TPHI)

Study record dates

Study Major Dates

• Study Start (Estimated): April 15, 2026
• Primary Completion (Estimated): August 1, 2026
• Study Completion (Estimated): August 1, 2026

Study Registration Dates

• First Submitted: November 20, 2025
• First Submitted That Met QC Criteria: December 1, 2025
• First Posted (Actual): December 4, 2025

Study Record Updates

• Last Update Posted (Actual): March 20, 2026
• Last Update Submitted That Met QC Criteria: March 17, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: ADORA-VI

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No