In this paper, the flattened disk Brazilian test was used to evaluate the critical fracture parameter of a pharmaceutical tablet made of compressed anhydrous lactose powder. Following previous works, the energy release rate function was build thanks to experimental tests and numerical simulations. During the experimental tests, a high speed camera was used to capture the crack tip location during the dynamic propagation and Rapid Crack Propagation mechanisms were observed. A numerical analysis was thus used to evaluate the dynamic correction factor needed to take into account the inertia effects due to the crack tip velocity. The results were then compared to those obtained with the classical analytic relation related to a crack propagation in a semi-infinite plate. After giving a range of fracture energy for the material, the necessity to take into account inertia effects in the estimate of the fracture energy of the material was finally discussed in the case of the Brazilian test.