An evaluation of the electronic tongue for the taste assessment of drugs and pharmaceutical formulations

The publication of the European Paediatric Regulation (EC No. 1901/2006) in January 2007 brought the issue of taste assessment of medicines to the forefront. This regulation requires the early submission of a paediatric investigation plan (PIP).In most cases the applicant is required to provide an overview of planned measures / performed studies of which taste masking and assessment are of particular relevance. Therefore, there has been an increased interest in the development of objective taste assessment methods. The first area in this thesis focused on investigating and understanding the mechanism of detection of the Insent® electronic tongue TS 5000Z. Within this area, sensor responses to molecules possessing similar structures were analysed. In addition, metformin hydrochloride, paracetamol and ibuprofen were also analysed. In the development of objective taste assessment methods, such methods have to correlate with human taste perception. To this end, the second area investigated the correlation of taste assessment between an untrained human taste panel (n=24) and the electronic tongue. The human taste panel were presented with extemporaneously prepared amlodipine suspension which they graded in a visual analogue scale (VAS). These scores were compared to those obtained from the electronic tongue. It is widely accepted that hot melt extrusion is useful for generating solid dispersions that have taste masking capability. However there are limited reports in the literature that assess taste masking efficacy using electronic tongues. The third area of this thesis focuses on generating solid dispersion of Eudragit®EPO and quinine hydrochloride dihydrate. Overall, three key messages are concluded from the work detailed in this thesis. Firstly, the detection mechanism is dependent on the ionic / ionisation of the molecule under investigation. Secondly, strong correlation is shown between taste scores from the human panel and those obtained from the electronic tongue. Lastly, melt extrudates with 30% and 50% of quinine hydrochloride released less than 10% of drug in the first three minutes of dissolution therefore showing taste masking via both UV spectrophotochemical and electronic tongue analysis