PubMed · 13733015
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J PARSONS, W T BEHER, G D BAKER. 1961. X-ray diffraction powder data for steroids.. https://pubmed.ncbi.nlm.nih.gov/13733015/
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The flow properties of pharmaceutical powders and blends used in solid oral dosage forms are an important consideration during dosage form development. The vibratory feeder method, a flow measurement technique that quantifies avalanche flow, has been adapted for measurement of the flow properties of common pharmaceutical powders used in solid oral dosage forms. The flow properties of 17 different powders were measured with the instrument, and the results are reported as a powder flow index (PFI). The PFI trends of the powders correlate well with flow properties reported in the literature. The flow properties of the powders were also measured with a commercially available avalanche instrument, the Aero-Flow, and the results were reported as the mean time to avalanche (MTA). Since the two instruments analyze the avalanche by different algorithms, the results were compared with nonparametric statistical evaluation of ranked data, and they were found to be in excellent agreement. A recommended procedure for measurement of powder flow with the vibratory feeder is presented.
The Peschl-split bed shear tester was utilised to study the formation of different liquid states during wet massing for granulation. Using lactose monohydrate as a model bulking agent the threshold between pendular and funicular state was found to be at about 6% (w/w) of liquid binder added to the wet mass, here a 5% colloidal solution of HPMC in water. The upper limit of the funicular state appeared to be at approximately 15% (w/w) of liquid binder. The threshold values obtained from the shear cell measurements did correlate with values obtained from dried granule characteristics such as granule density and compressive Young's modulus determined by Dynamic Mechanical Analysis. The compressive Young's modulus increased with an increasing density of the wet mass during the shear experiments and decreased with an increase in the angle of internal friction. The results suggest that stiffer granules were a result of densification, not the strength of liquid bridge bond formation.
The scaling up of a fluidized bed granulation process from small scale to production scale is often done empirically in the pharmaceutical industry. In this study, a more practical and systematic method was developed in order to achieve a similar granule size in the scaled up fluid bed. The scaling up is based on the relative droplet size, and the powder bed moisture content at the end of the spraying cycle. The present study describes the scaling up of the fluidized granulation process from small (5 kg scale) to medium (30 kg scale) and to production fluid bed scale (120 kg scale). The granulation process is scaled up with as target a geometric mean granule size of 400 microm. First, the effect of the relative droplet size on the granule size was investigated in the different fluid beds. The effect of the change in relative droplet size on the granule size was different for each fluid bed. Second, experimental design is applied on the small and the medium fluid scale, and regression models for the granule size are proposed in order to scale up the granulation process on the small to medium scale. The granulation process was also successful by scaling-up to the large fluid bed, considering only the relative droplet size.