title: Scale-up from batch to flow-through wet milling process for injectable depot formulation.
abstract: Injectable depot formulations are aimed at providing long-term sustained release of a drug into systemic circulation, thus reducing plasma level fluctuations and improving patient compliance. The particle size distribution of the formulation in the form of suspension is a key parameter that controls the release rate. In this work, the process of wet stirred media milling (ball milling) of a poorly water-soluble substance has been investigated with two main aims: (i) to determine the parametric sensitivity of milling kinetics; and (ii) to develop scale-up methodology for process transfer from batch to flow-through arrangement. Ball milling experiments were performed in two types of ball mills, a batch mill with a 30ml maximum working volume, and a flow-through mill with a 250ml maximum working volume. Milling parameters were investigated in detail by methodologies of QbD to map the parametric space. Specifically, the effects of ball size, ball fill level, and rpm on the particle breakage kinetics were systematically investigated at both mills, with an additional parameter (flow-rate) in the case of the flow-through mill. The breakage rate was found to follow power-law kinetics with respect to dimensionless time, with an asymptotic d50particle size in the range of 200-300nm. In the case of the flow-through mill, the number of theoretical passes through the mill was found to be an important scale-up parameter.
authors: Department of Chemical Engineering, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic; Zentiva, k.s., U Kabelovny 130, 102 00 Praha 10, Czech Republic.
authors: Róbert
authors: R
authors: Lehocký
authors: Zentiva, k.s., U Kabelovny 130, 102 00 Praha 10, Czech Republic.
authors: Daniel
authors: D
authors: Pěček
authors: Department of Chemical Engineering, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic. Electronic address: Frantisek.Stepanek@vscht.cz.
authors: František
authors: F
authors: Štěpánek
mesh_terms: D002626:Chemistry, Pharmaceutical / Q000379:methods*; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000138:chemical synthesis*; D007267:Injections; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012995:Solubility; D013535:Suspensions
chemical_list: D003692:Delayed-Action Preparations; D013535:Suspensions
keywords: Ball milling; Ball size; Particle size distribution; Power-law kinetics; Surfactant