Condition category
Infections and Infestations
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Opisthorchiasis is a neglected tropical disease caused by liver flukes (parasites) for which only a single drug is available, praziquantel. Praziquantel doses used for the treatment are still experimental and the nature of the drug has not yet been studied. We aim to compare the effectiveness and safety of four oral praziquantel doses in patients infected with Opisthorchis viverrini and to measure praziquantel disposition using dried blood spot technology.

Who can participate?
Adult men and women infected with O. viverrini can participate in the study.

What does the study involve?
Three stool samples will be collected on different days within a maximum of 5 days. Medical history of patients participating in the study will be assessed with a standardized and previously used questionnaire, in addition to a full clinical examination carried out by the study doctor. Participants will be randomly allocated to one of the four praziquantel doses or to receive a placebo (dummy). Praziquantel will be given based on weight. A small amount of blood will be collected by pricking the tip of the middle or ring finger. Blood will be collected at different time points after dosing. A few drops of blood will be transferred at each time point onto filter paper and dried for about 1 hour. The dried blood spot cards will be transported to Basel, Switzerland and stored at -20° C until they are analysed. Side effects will be carefully studied up to 72 hours after treatment by experienced doctors. The effectiveness of the treatment will be determined 19-25 days after treatment by collecting another three stool samples, collected on consecutive days, and microscopically examining the samples for eggs. Patients will be considered Opisthorchis negative if no eggs have been found in the stool or specimens.

What are the possible benefits and risks of participating?
This study will increase our understanding of the nature of the drug praziquantel. All procedures in this study are routinely conducted at a health facility. They do not bear any particular additional risks. Side effects are mild and include stomach pain and dizziness.

Where is the study run from?
The study will take in a village in remote Laos (single study site).

When is the study starting and how long is it expected to run for?
The study starts in August 2014 and runs until December 2014.

Who is funding the study?
Swiss National Science Foundation, Switzerland.

Who is the main contact?
Prof Jennifer Keiser

Trial website

Contact information



Primary contact

Prof Jennifer Keiser


Contact details

Socinstr. 57
PO Box

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Dose-finding and pharmacokinetic studies of praziquantel in patients infected with Opisthorchis viverrini: a randomized, controlled phase 2 single-blind dose-finding trial



Study hypothesis

The currently used praziquantel dosages are empirical and could be improved through dose-finding and pharmacokinetic studies.

Ethics approval

EKNZ 2014-163 and ethical clearance Lao PDR

Study design

Randomized, controlled phase 2 single-blind dose-finding trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet




Participants will be randomized to one of four treatment groups or a control group (given a placebo)
1. Praziquantel 30 mg/kg
2. Praziquantel 40 mg/kg
3. Praziquantel 50 mg/kg
4. Praziquantel 3 x 25 mg/kg

Intervention type



Phase II

Drug names


Primary outcome measures

Cure rate: measured 21 days post-treatment

Secondary outcome measures

1. Egg reduction rate: measured 21 days post-treatment
2. Pharmacokinetic parameters: measured up to 24 hours post-treatment
3. Safety: measured 3 hours and 24 hours post-treatment

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. Written informed consent signed by participant
2. Age 15-65 years
3. Able and willing to be examined by a study physician at the beginning of the study and 3 weeks after treatment
4. Able and willing to provide three stool samples at the beginning of the study and 3 weeks after treatment
5. Able and willing to provide 11 finger prick blood samples for PK studies
6. Infected with O. viverrini
7. Absence of major systemic illnesses as assessed by a medical doctor, upon initial clinical assessment
8. No known allergy to study medications

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. No written informed consent
2. Presence of any abnormal medical condition, judged by the study physician
3. History of acute or severe chronic disease such as liver or renal disease
4. Recent use of anthelminthic drug (within past 4 weeks)
5. Pregnancy or breastfeeding
6. Administration of any investigational product or use of any investigational device within 30 days prior to praziquantel administration. Subjects who have used drugs that may affect thepharmacokinetics of praziquantel from 15 days before dosing until the last PK sample, e.g., phenytoin, barbiturates, primidone, carbamazapine, oxcarbazepine, topiramate, felbamate, rifampicin, nelfinavir, ritonavir, griseofulvin, oral ketoconazole
7. Consumption of substances known to be potent inhibitors or inducers of CYP P450s such as grapefruit juice, grapefruit juice containing products, and herbal remedies or dietary supplements containing St John’s Wort, in the two weeks before dosing
8. Attending other clinical trials during the study
9. Below 15 years of age
10. Negative diagnostic result for Opisthorchis
11. Allergy to praziquantel

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Socinstr. 57

Sponsor information


Swiss Tropical and Public Health Institute (Switzerland)

Sponsor details

c/o Jennifer Keiser
Socinstr. 57
PO Box

Sponsor type

Research organisation



Funder type

Research organisation

Funder name

Swiss National Science Foundation (Switzerland)

Alternative name(s)

Swiss National Science Foundation, Fonds National Suisse de la Recherche Scientifique, Fondo Nazionale Svizzero per la Ricerca Scientifica, Fonds National Suisse, Fondo Nazionale Svizzero, Schweizerischer Nationalfonds, SNF

Funding Body Type

private sector organisation

Funding Body Subtype




Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes