Taste masking of an active pharmaceutical ingredient for veterinary application

The aim of this thesis was to mask the bitter taste of praziquantel. The product into which the taste masked formulations were to be incorporated was an oral paste intended for the treatment of cats. Four different approaches to achieve taste masking were tested. First of all, microspheres with the active ingredient being embedded into a polymer matrix consisting of Eudragit E were produced. Moreover, taste masking as a result of complexation with β-cyclodextrin was tested as the formation of a true inclusion complex of praziquantel in β-cyclodextrin could be demonstrated. Another technique included incorporation into lipid microparticles. Finally, praziquantel being a racemic drug the isolated enantiomers were tested separately for their acceptance. The taste masked formulations were then incorporated into different pastes (bases: water, Miglyol or PEG) according to their properties and the acceptance by cats was tested. A poor result was scored for the Eudragit E microspheres in PEG which was mainly caused by the solubility of the active ingredient in this base. The drug-β-cyclodextrin complex and the lipid particles were both tested in Miglyol and water. In an oily paste rather low acceptance values were scored whereas in an aqueous paste satisfactory levels were reached. These could be increased slightly upon addition of a flavor. This result could be equaled with an in situ formed complex between praziquantel and β-cyclodextrin in an aqueous paste which was desired due to production and registration purposes. The separated praziquantel enantiomers were also tested in water and significantly different values were reached for them with (−)-praziquantel being preferred to its (+)-enantiomer. The acceptance level for (−)praziquantel, however, was not significantly lower than that of the paste containing β-cyclodextrin and a flavor. Hence, an improvement of the results for (−)-praziquantel might be possible if taste masking agents were added. So in conclusion, taste masking of praziquantel was achieved in form of an aqueous paste containing β-cyclodextrin and a flavor as taste masking agents: the resulting paste is willingly taken by cats and also rated easily applicable by pet owners.