title: Direct pelletization in a rotary processor controlled by torque measurements. I. Influence of process variables.
abstract: The aim of this study was to elucidate the feasibility of using torque measurement to control the end point of a wet pelletization process in a rotary processor at varying levels of friction plate rotation speed, air gap pressure difference, and batch size. A 1:1 mixture of lactose monohydrate (200 mesh) and microcrystalline cellulose (PH-101) was granulated into pellets in an instrumented laboratory scale rotary processor using water as aqueous binder liquid. A full factorial designed study was performed to investigate the influence of the friction plate rotation speed (600 and 1200 rpm), the air gap pressure difference (1 and 3 kPa), the torque increase (0.4 and 0.8 N.m) and the batch size (500 and 1000 g) on the pellet properties. All pellets produced were round and showed a narrow size distribution. The geometric mean diameter varied from 400 to 1900 microns with a good reproducibility. Increasing the batch size and the rotation speed led to smaller pellets, whereas a higher torque produced larger pellets. This study showed that the process can be controlled by means of the torque increase because it was possible to produce pellets of a reproducible size by stopping the liquid addition at a certain torque level.
authors.affiliation: Department of Pharmaceutics, Royal Danish School of Pharmacy, Copenhagen, Denmark. JK@MAIL.DFH.DK
authors.forename: J
authors.initials: J
authors.lastname: Kristensen
authors.forename: T
authors.initials: T
authors.lastname: Schaefer
authors.forename: P
authors.initials: P
authors.lastname: Kleinebudde
mesh_terms: D004339:Drug Compounding / Q000295:instrumentation*; D005079:Excipients; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D011312:Pressure; D012044:Regression Analysis; D015203:Reproducibility of Results
chemical_list: D005079:Excipients