Haake minilab

Prior to HME processing, the excipients were passed through an ASTM #30-mesh screen to remove any aggregates that might have been formed. The constituents of all formulations shown in Table 1 were mixed using a V-shell blender (Maxiblend^®; GlobePharma, New Brunswick, NJ, USA) at 20 rpm for 20 min. The physical blends were subsequently transferred to the feeder of a co-rotating twin-screw extruder (Haake MiniLab, Thermo Electron; Newington, NH, USA). The screw speed was set at 100 rpm for all four formulations (F1–F4). The heating temperature for F1–F4 was 84, 70, 150, and 130°C, respectively. The extrudates were milled using a comminuting mill (Fitzpatrick, Model “L1A”; Elmhurst, IL, USA). The milled extrudates were sieved to a particle size ranging from 300–425 μm using the extrudates retained between the US #35 and US #40 sieves. The extrudates were stored in foil-lined polyethylene bags until further analysis and processing.

The polymers and drugs were sifted using a sieve (USP #30 screen size) and dried in an oven at 40°C to remove any residual moisture present. The materials were blended using a twin shell V-blender (GlobePharma, Maxiblend®) at 25 rpm for 15 min. Preliminary experiments were performed initially using a 6-mm counter-rotating mini extruder (Haake Minilab, Thermo Electron, Germany), and thereafter optimized formulations were finally extruded using the pilot scale 16-mm co-rotating twin screw extruder with a standard screw configuration as shown in Fig. 1 (16 mm, Prism Euro Lab, Thermo Fisher Scientific). The composition of different formulations, processing parameters, and percent drug released after lag time (6 h) using the 6-mm extruder is listed in Table I. Formulation compositions and processing parameters of experiments on the 16-mm extruder are listed in Table II. Initial extrudates obtained during the extrusion process were discarded until the extruder had attained a steady state, and then extrudates collected were cooled at ambient temperature and pelletized simultaneously using a pelletizer into pellets of 1, 2, and 3 mm in size. The extrudates were also milled using a comminuting mill (Fitzpatrick, model L1A) and sieved using a USP mesh screen (#25). The pellets were stored in poly bags in a desiccator until further evaluation.