An Evaluation of Process Variables in wet Granulation

Determination of significant factors in high-shear granulation process of sucrose with aqueous solution of sodium lauryl sulphate using partial least square regression approach

Sucrose as one of the most commonly used raw materials in pediatric formulations is soluble and sticky excipient and its manipulation in high shear granulators may be very difficult. Therefore, to determine the correct amount of liquid binder is very important because it falls in a very narrow range and may vary due to small variations in the material properties or environmental conditions. The possibility of using the sugar as powder for granulation may be very challenging because of solubility and moisture adsorption properties of crystalline sugar, especially if the binder solution is water. The aim of this study was trying to solve these problems and produce sucrose granules using high share granulation and water as a binding liquid, with properties required for final product good performance. By reducing the sucrose particle size and improving the uniformity of the size distribution, the differences of the processes of nucleation and growth for small and large particles might be reduced. According to the variable importance or VIP scores from the developed partial least square (PLS) model, raw material particle size is as influential variable as the quantity and composition of the granulation liquid (Gra), granulation time (Grn) and impeller rate (Imp). Keywords: sucrose, particle size distribution, high-shear granulation, partial least square

Utilization of date syrup as a tablet binder, comparative study

The aim of this study was to investigate the possibility of using dates syrup as a tablet binder. Dates syrup (40%, 50%, 60% w/w dates syrup:water) was utilized for the granulation of sodium bicarbonate and calcium carbonate as examples for water-soluble and water-insoluble materials; correspondingly. Those two materials represent examples of bulky drugs as well. Starch paste (10% w/w starch in water) and sucrose syrup (50% w/w sucrose in water), the well-known tablet binders, were used in the granulation of the same materials for the sake of comparison. The granulations were evaluated with regard to particle size and particle size distribution, granule strength, bulk density, flowability, moisture content and compression behavior. In addition, tablets prepared and evaluated from these granules. Taste and flavor of the prepared tablet have been tested by seven healthy volunteers. Within the scope of this work, dates syrup showed excellent properties as a tablet binder in comparison to starch paste or sucrose syrup for the granulation of both water-soluble and water-insoluble materials. Also, better flavoring and masking taste have been noticed from an evaluation by human volunteers demonstrating the usefulness of the date syrup as sweetener and flavoring the tablets in addition to its use as binder.

Predicting particle size during fluid bed granulation using process measurement data

In this study, a new concept for particle size prediction during the fluid bed granulation is presented. Using the process measurements data obtained from a design of experimental study, predictive partial least squares models were developed for spraying and drying phases. Measured and calculated process parameters from an instrumented fluid bed granulation environment were used as explaining factors, whereas an in-line particle size data determined by spatial filtering technique were used as response. Modeling was carried out by testing all possible combinations of two to six process parameters (factors) of the total of 41 parameters. Eleven batches were used for model development and four batches for model testing. The selected models predicted particle size (d50) well, especially during the spraying phase (Q2=0.86). While the measured in-line d50 data were markedly influenced by different process failures, e.g., impaired fluidization activity, the predicted data remained more consistent. This introduced concept can be applied in fluid bed granulation processes if the granulation environment is soundly instrumented and if reliable real-time particle size data from the design of experiment batches are retrieved for the model development.

Design and evaluation of deformable talc agglomerates prepared by crystallo-co-agglomeration technique for generating heterogeneous matrix

The crystallo-co-agglomeration technique was used to design directly compressible and deformable agglomerates of talc containing the low-dose drug bromhexine hydrochloride (BXH). The process of agglomeration involved the use of dichloromethane as a good solvent and bridging liquid for BXH, water as a poor solvent, talc as diluent, and Tween 80 to aid dispersion of BXH and diluent into the poor solvent. Hydroxypropyl methylcellulose (50 cps) 4% wt/wt was used to impart the desired mechanical strength and polyethylene glycol 6000 5% wt/wt was used to impart the desired sphericity to the agglomerates. Clarity of the supernatant was considered an endpoint for completion of the agglomeration process. The drug-to-talc ratio in optimized batch 1 (BT1) and batch 2 (BT2) was kept at 1:15.66 and 1:24, respectively. The spherical agglomerates obtained were evaluated for topographic, micromeritic, mechanical, deformation, compressional, and drug release properties. The agglomeration yield and drug entrapment for both batches were above 94% wt/wt. Crushing strength and friability studies showed good handling qualities of agglomerates. Heckel plot studies showed low mean yield pressure and high tensile strength, indicating excellent compressibility and compactibility of agglomerates. Diametral and axial fracture of compacts showed deformation of agglomerates revealing formation of a heterogeneous compact. Drug release was sustained for 9 hours and 5 hours from BT1 and BT2, respectively, in 0.1N HCl. Hence, the crystallo-co-agglomeration technique can be successfully used for obtaining spherical, deformable, and directly compressible agglomerates, generating a heterogeneous matrix system and providing sustained drug release.

Study growth kinetics in fluidized bed granulation with at-line FBRM

In this study, a novel at-line focused beam reflectance measurement (FBRM) technique was developed to investigate granule growth in a fluidized bed granulation (FBG). The chord length distribution (CLD) measured by the FBRM was used to represent granule particle size distribution (PSD). Through a systematic study, it was proved that the trends of the chord length measured by the at-line FBRM technique were identical to those measured by a laser diffraction instrument and sieve analysis in spite of different measurement mechanisms. The portable at-line FBRM technique was successfully applied to a granule growth kinetics study for a fluidized bed granulation performed in a Glatt GPCG-1 granulator. Granule size evolution was clearly exhibited by the at-line FBRM. Spray rate was found to be the most significant factor on the granule growth compared with the other two factors: binder solution concentration and intra- to extra-granular microcrystalline cellulose (MCC) ratio for the formulation studied in this work. The CLD evolution measured by the FBRM confirmed that the granule agglomeration was mainly dominated by the binder on the granule surface. The at-line FBRM enables us to select appropriate process parameters and effectively control the fluid bed granulation process.

Using experimental design to optimize the process parameters in fluidized bed granulation on a semi-full scale

A face-centered central composite design was applied in order to optimize the granulation process on a semi-full scale (30-kg batch) for the geometric mean granule size. The granulation process variables investigated were: inlet air temperature, inlet airflow rate, spray rate and inlet air humidity. Based on the process variables, the theoretical powder bed moisture content after the spraying process and a measure for the droplet size were determined. Multiple regression modeling was used to develop two models for the granule size: an empirical model, based on the four process parameters, and a fundamental model, based on the balance between the granule growth affected by the theoretical powder bed moisture content and the droplet size and the breakage effect of the airflow rate. These regression models were used to optimize the granulation process to obtain a granule size between 300 and 500 microm. Additional experiments confirmed that these models were valid. Other granule properties, namely the geometric standard deviation, the Hausner index, the angle of repose and the moisture content, were evaluated at the optimal operation conditions.

Simultaneous optimization of wet granulation process involving factor of drug content dependency on granule size

Computer optimization technique was applied to the simultaneous optimization of wet granulation process by a high-speed mixer granulator. Four pharmaceutical properties, including yield, drug content uniformity, geometrical mean diameter of granules, and uniformity of granule size, were selected to evaluate the quality of the granules. In particular, dependence of drug content uniformity on granule size was investigated using two model drugs, ascorbic acid and ethenzamide. An appreciable dependence of ascorbic acid content on granule size was not observed in model formulations. On the other hand, ethenzamide was contained more in small-size granules, and its content was decreased with an increase in amounts of hydroxypropyl cellulose (HPC-L; used as a binder) and binder solution. These observations suggested that drug content uniformity is influenced not only by drug solubility in the binder solution, but also by the use of HPC-L. A simultaneous optimal point incorporating four pharmaceutical properties was obtained using the generalized distance function. The experimental values of the four response variables obtained in newly prepared granules were found to correspond well with the predicted values of both granules containing ascorbic acid and ethenzamide. These results suggested that computer optimization would benefit the wet granulation process even if drug content segregation was involved in the process. Further, data obtained from computer optimization, in particular the contour diagram, will be valuable in the process validation.

Preparation and characterization of oil-in-water type poly (D,L-lactic acid) microspheres containing testosterone enanthate

Poly (D,L-lactic acid) (PLA) microspheres containing testosterone enanthate (ET) were prepared by using an oil-in-water (O/W) emulsion technique. The size distribution of the microspheres obtained could be explained by a log-normal distribution, and as a result, it was found that ET fully incorporates into microspheres even when the drug is loaded at up to 50%. On the other hand, the dissolution behavior of ET from microspheres was strongly dependent on particle size, suggesting that dissolution of the drug from microspheres can be easily controlled by controlling the preparative conditions.