The influence of non-ionisable excipients on precipitation parameters measured using the CheqSol method

Etherson, Kelly and Halbert, Gavin and Elliott, Moira (2016) The influence of non-ionisable excipients on precipitation parameters measured using the CheqSol method. Journal of Pharmacy and Pharmacology, 68 (9). pp. 1131-1142. ISSN 0022-3573

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    Abstract

    Objectives: The aim of this study was to determine the influence of non-ionisable excipients hydroxypropyl--cyclodextrin (HPCD) and poloxamers 407 and 188 on the supersaturation and precipitation kinetics of ibuprofen, gliclazide, propranolol and atenolol induced through solution pH shifts using the CheqSol method. Methods: The drug’s kinetic and intrinsic aqueous solubility was measured in the presence of increasing excipient concentrations using the CheqSol solubility method. Experimental data for example rate of change of pH with time was also examined to determine excipient induced parachute effects and influence on precipitation rates. Key Findings: The measured kinetic and intrinsic solubilities provide a determination of the influence of each excipient on supersaturation index and the area under the CheqSol curve can measure the parachute capability of excipients. The excipients influence on precipitation kinetics can be measured with novel parameters for example the precipitation pH or percentage ionized drug at the precipitation point which provide further information on the excipient induced changes in precipitation performance. Conclusion: This method can therefore be employed to measure the influence of non-ionisable excipients on the kinetic solubility behavior of supersaturated solutions of ionisable drugs and to provide data, which discriminates between excipient systems during precipitation.