Online Reporter
Remember Deketeke-Herald Correspondent
FOR decades, the fight against bilharzia (schistosomiasis) has had an uncomfortable truth at its centre: while treatment existed, the youngest children (under five) were largely left out.
Praziquantel, the drug used globally to treat schistosomiasis, has long been effective. But it was designed for adults and older children.
The tablet, large, bitter and dosed at 600mg, was simply not suitable for children under the age of five.
“The problem was not that we didn’t have a drug,” said lead scientist Dr Remco Vrueh, one of the scientists behind the development of paediatric praziquantel.
“The problem was that the tablet was too big, the dose was not well defined for very young children and there was a real risk of choking.”
As a result, millions of preschool-aged children, often those most exposed to infected water, were excluded from routine treatment programmes.
That gap is what sparked a global scientific effort that has now resulted in the world’s first child-friendly praziquantel tablet, specifically designed for young children in schistosomiasis-endemic regions.
From the outset, the scientists involved agreed that this could not be a minor adjustment of an adult medicine.
“What we did was to sit together with a number of partners and ask a very basic question,” Dr Vrueh said. “What would actually be suitable for children below the age of five?”
Small children cannot swallow large tablets, crushing tablets risks incorrect dosing. Syrups are costly, unstable and difficult to transport.
“One of the key ideas we came up with was that the tablet had to be dispersible. You put it in water, it disperses evenly, and the child can drink the correct dose safely,” he said.
But safety and ease of use were only part of the challenge. The team also had to consider where the medicine would be used.
“This is an area where it is very hot,” Dr Vrueh said. “So, the tablet had to withstand humidity and high temperatures for long periods of time.”
The formulation was tested extensively under harsh conditions, including exposure to temperatures as high as 40 degrees Celsius.
“We tested it to make sure that if you store it under these conditions, it still functions in the same way as it should,” he says.
Only once the tablet proved stable in such environments did development move forward.
Another major obstacle was taste.
“Praziquantel has a very bitter taste,” Dr Vrueh said. “I tasted it myself, and it is horrible.”
For children, bitterness can mean refusal or vomiting, rendering treatment ineffective. To address this, scientists incorporated a sugar-based molecule into the tablet to mask the bitterness without affecting the drug’s effectiveness. Taste acceptability was then tested in Tanzania among children aged between about five and 11.
“They did not have to swallow the tablet,” Dr Vrueh said.
“They just took it in their mouth, swirled it, spat it out, and scored whether the sensation was acceptable or not.”
The results showed that the taste had improved enough to proceed.
Because paediatric praziquantel was a new formulation, it had to go through the full clinical trial process.
“We started with a Phase One trial,” Dr Vrueh said. “That looks at what happens when you take it in, how fast it is absorbed and how fast it leaves the body.”
Phase Two focused on determining the correct dosage and was conducted in Côte d’Ivoire.
Then came Phase Three, the largest and most critical stage.
“To me, Phase Three was the most important,” he said. “That is where you really look at efficacy. Does it treat the disease? Is the child cured?”
The results confirmed that the new formulation was both safe and effective in treating schistosomiasis in young children.
All the trial data was compiled into a comprehensive regulatory dossier and submitted to the European Medicines Agency (EMA) at the end of 2022.
The review process included not only European regulators but also expert input from Africa.
“There were experts from Africa, including Professor Mutapi and others,” Dr Vrueh said. “They didn’t decide approval, but they were able to share their perspectives on why this medicine matters.”
In December 2023, the EMA issued a positive opinion. With that approval, the dossier was submitted to the World Health Organization, whose prequalification list is a key reference point for many African countries.
“The WHO stamp of approval is something many countries look for,” Dr Vrueh said.
The WHO subsequently approved the medicine.
The first African regulatory approval came in August 2025, in Tanzania. More countries are now in the process of reviewing the medicine for approval.
Dr Vrueh is quick to stress that the achievement belongs to a collective effort.
“I’m the president of a consortium with 13 partners. We developed the formulation and conducted pilot studies in Côte d’Ivoire, Uganda and Kenya.”
However, regulatory submissions and large-scale supplies are being handled by pharmaceutical company Merck, a long-standing partner in the project.
“The consortium cannot go to regulators like EMA on its own,” he said. “That has to be done by a pharmaceutical company.”
The tablet’s development has been truly global.
“It was first developed in Japan then further optimised in Germany,” Dr Vrueh said.
Large-scale production was established in Brazil, where the formulation was tested again for stability.
Now, a technology transfer is underway to a manufacturer in Nairobi, Kenya, bringing production closer to the communities that need it most.
“This completes the circle,” he said.
“It will be produced on the African continent and supplied to African countries.”
For the consortium, the work is largely complete.
“We have reached the end of the road,” Dr Vrueh said. “And that is a good thing.”
The medicine is approved, produced and ready for use.
For millions of children previously excluded from treatment, the impact is game changing, even if it arrives quietly.
A small tablet, a glass of water and, at last, inclusion in the fight against bilharzia.
