The pediatric formulation

The Pediatric Praziquantel Consortium is working on a pediatric praziquantel formulation suitable for use in the target group of preschool-age children (3 months to 6 years). Compared to the praziquantel tablets commercially available today, the new formulation contains only the biologically active L-praziquantel enantiomer, and not the pharmacologically inactive D-praziquantel enantiomer present in the racemic mixture. The formulation is a small, orally dispersible tablet with an acceptable taste, and which should also withstand the challenges presented by a tropical climate.

Getting started: a need for orally dispersible tablets

Soon after its formation, the Consortium collaborated with a panel of experts in schistosomiasis and pediatric formulations, at a meeting in Geneva in August 2012. The goal was to develop a target product profile (TPP) delineating both required and desirable formulation features. 

The participants agreed on a need for orally dispersible tablets (ODTs) or fast dispersible tablets, administered as a single dose, to treat children aged 3 months to 6 years infected with S. mansoni and/or S. haematobium, the two most prevalent species of schistosomes. The tablets should be suitable both for individual case treatments and for mass treatment campaigns, and remain stable in a tropical climate, meeting WHO zone IVb stability requirements. 

Formulation technology

Astellas Pharma Inc. (Japan) took on the initial pediatric formulation development of praziquantel for early clinical phases based on its pharmaceutical technologies. The pediatric tablets that Astellas Pharma developed are at about one-fourth the size of commercial Cesol 600 mg praziquantel tablets and have orally dispersible property so that they can be taken with or even without water. Moreover, taste masking agents introduced to the pediatric formulation enabled children to swallow praziquantel more easily, which promises enhanced compliance and pharmacological effects. Apart from palatability, efficacy, safety and affordability of the new formulation, an appropriate shelf-life to withstand the challenging field temperature and logistics that prevail in Africa are the striven key characteristics.

After successful technology transfer from Astellas to Merck (Germany) and Farmanguinhos (Brazil), both partners started manufacturing and supply of clinical trial material. Further formulation development and production process optimization activities were initiated simultaneously to support the later development phases. 

Active pharmaceutical ingredient (API)

The existing praziquantel formulation is a racemic mixture of levopraziquantel (L-praziquantel ) and dextropraziquantel (D-praziquantel ). Only one of these components is pharmacologically active: the L-praziquantel enantiomer. The other component, D-praziquantel has been shown to be inactive and contributes to the bitter taste that makes treating young children difficult. 

Apart from using the current racemic praziquantel active pharmaceutical ingredient (API) to develop the pediatric formulation, another strategy employed by the Consortium was to use only the biologically active R-praziquantel enantiomer, and not the pharmacologically inactive S-praziquantel enantiomer present in the racemic mixture). This was expected to decrease the amount of the required dose and to decrease its severe bitter taste. 

Read on to learn more about the development program, or visit our timeline for information on where we stand.