Technical Note: Miniaturized Intrinsic Dissolution Rate (Mini-IDR™) Measurement of Griseofulvin and Carbamazepine

Griseofulvin and carbamazepine were selected as model drugs to compare measurements of disk intrinsic dissolution rate (IDR) by a traditional (Wood apparatus) USP method (500-mg pellet, 900 mL media) and a new miniaturized method (5-mg pellet, 15 mL media) at 37 °C and 100 rpm. An in situ fiber optic UV instrument was used to collect dissolution data, with IDR calculated and displayed in real time. The IDR values from the present study and those reported by an FDA group (1) agree well, suggesting that the scale-down of hydrodynamics may be a reliable option for early development studies, where quantities of API are often highly limited.