Investigation of influence of process variables on mechanical strength, size and homogeneity of pharmaceutical granules produced by fluidised hot melt granulation

Binder-free twin-screw melt granulation: An effective approach to manufacture high-dose API formulations

This study investigates the use of twin-screw binder-free melt granulation (BFMG) in the development of high-dose solid dose formulations for low melting point thermally stable drugs. Both ibuprofen and guaifenesin are examined. By granulating pure API powder, it is shown that BFMG can successfully be used to produce granules that contain 100% API. A design of experiments (DoE) response surface methodology was used to establish the design space for the end-product. The effects of the most relevant process variables (barrel operating temperature, powder feed rate, screw speed and screw configuration) on granule properties (outlet temperature, size distribution, morphology, flowability, compressibility, porosity) and tablet attributes (tensile strength and in-vitro dissolution) were thoroughly studied. Barrel temperature (alone or in interactions with the other variables) represented the most significant variable for both drugs since it governs the formation of granules by partial melting and subsequent agglomeration of the fed powder. Interestingly, the shear action originated by screw speed and screw configuration resulted in various significant responses depending on the drug substance, indicating that it can also be affected by the nature of the processed molecule. Flow properties were improved (i.e., lower Hausner ratio) for both drugs after formation of granules. Tabletability was also tested by preparing 600 mg tablets for all samples. Surprisingly, the resulting granules were highly compactible, requiring only 1% lubricant to form strong tablets containing 96% API and 3% disintegrant. The results also showed that tablets become harder as the granule size increased, especially for guaifenesin. As expected, in-vitro dissolution results indicated that tablets and capsules showed slightly slower dissolution rates than the granules.

A novel insight into fluid bed melt granulation: Temperature mapping for the determination of granule formation with the in-situ and spray-on techniques

The in-line control of pharmaceutical processes has become a necessary tool for the evaluation and follow-up of pharmaceutical dosage forms. In this study, a novel approach to the evaluation of conditions established in a conical fluid bed granulator during the in-situ and spray-on fluid bed melt granulation (FBMG) techniques was developed. The determination of temperature mappings allowed the characterization of the critical zones during the melt granulation and the prediction of the volume of the wetting zone, hence enabling the identification of the areas of optimal granule growth. Two grades of polyethylene glycol (PEG 2000 and 6000) were used as meltable binders in three binder spraying rates and droplet size fractions for spray-on and three binder particle sizes and contents for in-situ. The results showed the presence of intense heat exchange in the bottom of the bed during the in-situ technique and under the spraying nozzle during the spray-on technique, identified as the wetting zone. Isotherm maps enabled the identification of the transition between the wetting, cooling and consolidation zones for the spray-on and the cooling zone for the in-situ technique. The shape and volume of the wetting zone was highly dependent on binder spraying rate and spraying pressure for spray-on and binder particle size and content for in-situ FBMG. Granule size and size distribution were correlated to the volume of the wetting zone and an optimized wetting volume interval was determined for both spray-on and in-situ techniques for the optimal quality attributes of the granules.