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The purpose of this study was to conduct an interlaboratory ring-study, with six partners (academic and industrial), investigating the measurement of intrinsic dissolution rate (IDR) using surface dissolution imaging (SDI) equipment. Measurement of IDR is important in pharmaceutical research as it provides characterising information on drugs and their formulations. This work allowed us to assess the SDI's interlaboratory performance for measuring IDR using a defined standard operating procedure (see supporting information) and six drugs assigned as low (tadalafil, bromocriptine mesylate), medium (carvedilol, indomethacin) and high (ibuprofen, valsartan) solubility compounds. Fasted State Simulated Intestinal Fluid (FaSSIF) and blank FaSSIF (without sodium taurocholate and lecithin) (pH 6.5) were used as media. Using the standardised protocol an IDR value was obtained for all compounds and the results show that the overall IDR rank order matched the solubility rank order. Interlaboratory variability was also examined and it was observed that the variability for lower solubility compounds was higher, coefficient of variation > 50%, than for intermediate and high solubility compounds, with the exception of indomethacin in FaSSIF medium. Inter laboratory variability is a useful descriptor for understanding the robustness of the protocol and the system variability. On comparison to another published small-scale IDR study the rank ordering with respect to dissolution rate is identical except for the high solubility compounds. This results indicates that the SDI robustly measures IDR however, no recommendation on the use of one small scale method over the other is made.

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Objectives: The aim of this study was to determine the influence of non-ionisable excipients hydroxypropyl--cyclodextrin (HPCD) 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.