Development and evaluation of taste-masked drug for paediatric medicines - application to acetaminophen

The aim of this work was to produce and characterize taste-masked powders of a model drug (acetaminophen) prepared using potentially tolerable and safe excipients for paediatric use, i.e. sodium caseinate and lecithin. The powders were produced by spray-drying aqueous dispersions. The characteristics of taste-masked drug particles were determined by scanning electron microscopy, differential scanning calorimetry and X-ray photoelectron spectroscopy to analyse the surface composition of particles. Taste assessment was approached by an indirect method through drug release studies. We developed a method with a syringe pump using small volumes of aqueous medium and low flow rates, to mimic the behaviour in the mouth. This method was compared to the electronic tongue analysis. SEM, DSC and XPS analysis indicated differences in surface composition of spray-dried particles according to the caseinate/lecithin ratio and to relate it with taste-masking. The "coating" consisting of caseinate and lecithin had a significant role in decreasing the release of drug during the first 2 min and so in taste-masking. Higher content in lecithin results in higher taste-masking efficiency. The association of sodium caseinate and lecithin seems to be promising to mask the bitterness of acetaminophen. A good agreement between release study and electronic tongue analysis was established.