Gramaglia, D, Conway, Barbara R, Kett, V, Malcolm, R and Batchelor, Hannah (2005) High speed DSC (hyper-DSC) as a tool to measure the solubility of a drug within a solid or semi-solid matrix. International Journal of Pharmaceutics, 301 (1-2). pp. 1-5. ISSN 0378-5173

Conventional differential scanning calorimetry (DSC) techniques are commonly used to quantify the solubility of drugs within polymeric-controlled delivery systems. However, the nature of the DSC experiment, and in particular the relatively slow heating rates employed, limit its use to the measurement of drug solubility at the drug's melting temperature. Here, we describe the application of hyper-DSC (HDSC), a variant of DSC involving extremely rapid heating rates, to the calculation of the solubility of a model drug, metronidazole, in silicone elastomer, and demonstrate that the faster heating rates permit the solubility to be calculated under non-equilibrium conditions such that the solubility better approximates that at the temperature of use. At a heating rate of 400 °C/min (HDSC), metronidazole solubility was calculated to be 2.16 mg/g compared with 6.16 mg/g at 20 °C/min.