William C. Stagner

Inline Real-Time Near-Infrared Granule Moisture Measurements of a Continuous Granulation–Drying–Milling Process

The purpose of this research was to use inline real-time near-infrared (NIR) to measure the moisture content of granules manufactured using a commercial production scale continuous twin-screw granulator fluid-bed dryer milling process. A central composite response surface statistical design was used to study the effect of inlet air temperature and dew point on granule moisture content. The NIR moisture content was compared to Karl Fischer (KF) and loss on drying (LOD) moisture determinations. Using multivariate analysis, the data showed a statistically significant correlation between the conventional methods and NIR. The R2 values for predicted moisture content by NIR versus KF and predicted moisture values by NIR versus LOD were 0.94 (p < 0.00001) and 0.85 (p < 0.0002), respectively. The adjusted R2 for KF versus LOD correlation was 0.85 (p < 0.0001). Analysis of the response surface design data showed that inlet air temperature over a range of 35–55°C had a significant linear impact on granule moisture content as measured by predicted NIR (adjusted R2 = 0.84, p < 0.02), KF (adjusted R2 = 0.91, p < 0.0001), and LOD (adjusted R2 = 0.85, p < 0.0006). The inlet air dew point range of 10–20°C did not have a significant impact on any of the moisture measurements.

Application of Multivariate Methods to Evaluate the Functionality of Bovine‐ and Vegetable‐Derived Magnesium Stearate

This work distinguishes and quantifies the effects of bovine- and vegetable-derived magnesium stearate (MgSt) molecular and macroscopic properties on lubrication efficiency using multivariate analysis. Principal component analysis (PCA) and partial least-square regression (PLS) were used to evaluate and quantify the lubricant effectiveness on a model tablet formulation. PCA score and loading plots showed a separation of model formulations based on the MgSt sources, which indicated different bovine- and vegetable-derived MgSt lubrication potential. PLS quantified the MgSt molecular [enthalpy of dehydration (ΔHd), enthalpy of melting (ΔHm), percent crystallinity, and moisture content] and macroscopic [particle size (d50 ), specific surface area (SSA-MgSt), and MgSt Hausner ratio (HF-MgSt)] properties, their interactions, and square effects on formulation powder flow and tableting properties relating to MgSts lubrication effectiveness. For crystalline MgSt, moisture content, HF-MgSt, d50 , and SSA-MgSt showed a major influence on the lubrication efficiency compared with the other MgSt molecular properties (percent crystallinity, ΔHm, and ΔHd). Amorphous MgSt showed poor lubrication, and none of its molecular or macroscopic properties showed significant effects on lubrication efficiency.

Physico-Mechanical Properties of Coprocessed Excipient MicroceLac® 100 by DM(3) Approach.

PurposeTo determine the effect of relative humidity (RH) and hydroxypropyl methylcellulose (HPMC) on the physico-mechanical properties of coprocessed MacroceLac® 100 using ‘DM3’ approach.MethodsEffects of RH and 5% w/w HPMC on MacroceLac® 100 Compressibility Index (CI) and tablet mechanical strength (TMS) were evaluated by ‘DM3’. The ‘DM3’ approach evaluates material properties by combining ‘design of experiments’, material’s ‘macroscopic’ properties, ‘molecular’ properties, and ‘multivariate analysis’ tools. A 4X4 full-factorial experimental design was used to study the relationship of MacroceLac® 100 molecular properties (moisture content, dehydration, crystallization, fusion enthalpy, and moisture uptake) and macroscopic particle size and shape on CI and TMS. A physical binary mixture (PBM) of similar composition to MacroceLac® 100 was also evaluated. Multivariate analysis of variance (MANOVA), principle component analysis, and partial least squares (PLS) were used to analyze the data.ResultsMANOVA CI ranking was: PBM-HPMC > PBM > MicroceLac®100 > MicroceLac®100-HPMC (p < 0.0001). MANOVA showed PBM’s and PBM-HPMC’s TMS values were lower than MicroceLac®100 and MicroceLac®100-HPMC (p < 0.0001). PLS showed that % RH, HPMC, and several molecular properties significantly affected CI and TMS.ConclusionsSignificant MicroceLac®100 changes occurred with % RH exposure affecting performance attributes. HPMC physical addition did not prevent molecular or macroscopic matrix changes.

Vegetable-derived magnesium stearate functionality evaluation by DM3 approach

This study quantifies the lubricating efficiency of two grades of crystalline vegetable-derived magnesium stearate (MgSt-V) using the DM(3) approach, which utilizes design of experiments (D) and multivariate analysis techniques (M3) to evaluate the effect of a materials (M1) molecular and macroscopic properties and manufacturing factors (M2) on critical product attributes. A 2(3) factorial design (2 continuous variables plus 1 categorical factor) with three center points for each categorical factor was used to evaluate the effect of MgSt-V fraction and blend time on running powder basic flow energy (BFE), tablet mechanical strength (TMS), disintegration time (DT), and running powder lubricant sensitivity ratio (LSR). Molecular characterization of MgSt-V employed moisture sorption-desorption analysis, (13)C nuclear magnetic resonance spectroscopy, thermal analysis, and powder X-ray diffraction. MgSt-V macroscopic analysis included mean particle size, specific surface area, particle morphology, and BFE. Principal component analysis and partial least squares multivariate analysis techniques were used to develop predictive qualitative and quantitative relationships between the molecular and macroscopic properties of MgSt-V grades, design variables, and resulting tablet formulation properties. MgSt-V fraction and blending time and their square effects showed statistical significant effects. Significant variation in the molecular and macroscopic properties of MgSt-V did not have a statistically significant impact on the studied product quality attributes (BFE, TMS, DT, and LSR). In setting excipient release specifications, functional testing may be appropriate in certain cases to assess the effect of statistically significant different molecular and macroscopic properties on product quality attributes.

Effect of Tapped Density, Compacted Density, and Drug Concentration on Light‐Induced Fluorescence Response as a Process Analytical Tool

The effect of tapped density, compacted density, and fluorescent drug concentration on the light-induced fluorescence (LIF) response is reported. The fluorescent response to powder mixtures containing 0.25%-10.00% w/w fluorescent active pharmaceutical ingredient (API) was evaluated over a density range of about 0.641-1.370 g/cm(3) . Blend concentrations up to 4.00% w/w API showed a linear trend in LIF response with increasing tapped and compacted density. API concentrations of 4.00% w/w or greater exhibited a negative parabolic trend in LIF response. The LIF responses were fitted to a quadratic model equation that included an interaction term between material density and API concentration (adjusted R(2) = 0.975 and p < 0.0001). All model terms were highly significant, including the material density-API concentration interaction (p < 0.0001). Being aware of the sensitivity of the LIF response to material density changes and the related changes in apparent concentration are important in implementing LIF as a process analytical tool for processes such as blending, roller compaction, and tableting.

Evaluation of the Moisture Prediction Capability of Near-Infrared and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy Using Superdisintegrants as Model Compounds

The superdisintegrants (SDs) moisture content measurement by near-infrared (NIR) spectroscopy and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy has been evaluated against thermogravimetric analysis as a reference method. SDs with varying moisture content were used to build calibration and independent model verification data sets. Calibration models were developed based on the water-specific NIR and ATR-FTIR spectral regions using partial least-square regression methods. Because of the NIR water low molar absorptivity, NIR spectroscopy handled higher moisture content (∼81%, w/w) than ATR-FTIR (∼25%, w/w). A two-way ANOVA test was performed to compare R(2) values obtained from measured and predicted moisture content (5%-25%, w/w) of SDs. No statistically significant difference was observed between the predictability of NIR and ATR-FTIR methods (p = 0.3504). However, the interactions between the two independent variables, SDs, and analytical methods were statistically significant (p = 0.0002), indicating that the predictability of the analytical method is material dependent. Thus, it would be important to recognize this highly dependent material and analytical method interaction when using NIR moisture analysis in process analytical technology to analyze and control critical quality and performance attributes of raw materials during processing with the goal of ensuring final product quality attributes.

Physical Properties and Solubility Studies of Nifedipine-PEG 1450/HPMCAS-HF Solid Dispersions

Abstract Low-order high-energy nifedipine (NIF) solid dispersions (SDs) were generated by melt solvent amorphization with polyethylene glycol (PEG) 1450 and hypromellose acetate succinate (HPMCAS-HF) to increase NIF solubility while achieving acceptable physical stability. HPMCAS-HF was used as a crystallization inhibitor. Individual formulation components, their physical mixtures (PMs), and SDs were characterized by differential scanning calorimetry, powder X-ray diffraction, and Fourier transform infrared spectroscopy (FTIR). NIF solubility and percent crystallinity (PC) were determined at the initial time and after 5 days stored at 25 °C and 60% RH. FTIR indicated that hydrogen bonding was involved with the amorphization process. FTIR showed that NIF:HPMCAS-HF intermolecular interactions were weaker than NIF:PEG 1450 interactions. NIF:PEG 1450 SD solubilities were significantly higher than their PM counterparts (p < 0.0001). The solubilities of NIF:PEG 1450:HPMCAS-HF SDs were significantly higher than their corresponding NIF:PEG 1450 SDs (p < 0.0001-0.043). All the SD solubilities showed a statistically significant decrease (p < 0.0001) after storage for 5 days. SDs PC were statistically lower than their comparable PMs (p < 0.0001). The PCs of SDs with HPMCAS-HF were significantly lower than SDs not containing only PEG 1450. All SDs exhibited a significant increase in PC (p < 0.0001–0.0089) on storage. Thermogravimetric analysis results showed that HPMCAS-HF bound water at higher temperatures than PEG 1450 (p < 0.0001–0.0039). HPMCAS-HF slowed the crystallization process of SDs, although it did not completely inhibit NIF crystal growth. Graphical Abstract

Acyclovir Chemical Kinetics with the Discovery and Identification of Newly Reported Degradants and Degradation Pathways Involving Formaldehyde as a Degradant and Reactant Intermediate

The purpose of this research was to determine acyclovir (ACV) acidic degradation kinetics which is relevant to gastric retentive device product design. A stability-indicating method revealed two unknown degradation products which have been identified by mass spectrometry as ACV and guanine formaldehyde adducts. In addition to the formation of these adducts, a proposed degradation scheme identifies the formation of methyl acetal ethylene glycol, formaldehyde, ethylene glycol, and guanine as additional ACV degradation products. pH-rate profiles were explained by using a rate law which assumed acid-catalyzed hydrolysis of protonated and unprotonated ACV. The predicted and observed rate constants were in good agreement. Data-driven excipient selection recommendations were based on the chemical kinetic study results, degradation scheme, and pH-rate profiles. The average activation energy for the degradation reaction was determined to be 31.3±1.6kcal/mol. The predicted ACV t90% at 37°C and pH 1.2 was calculated to be 7.2days. As a first approximation, this suggests that ACV gastric retentive devices designed to deliver drug for 7days should have acceptable drug product stability in the stomach.

Deciphering magnesium stearate thermotropic behavior

ABSTRACT Magnesium stearate (MgSt) is the most commonly used excipient for oral solid dosage forms, yet there is significant commercial physicochemical variability that can lead to variable performance of critical product attributes. Differential scanning calorimetry (DSC) is often used as a quality control tool to characterize MgSt, but little data is available regarding the physicochemical relevance for the DSC thermograms. The main aim of this study was to decipher MgSts complex thermotropic behavior using DSC, thermogravimetric analysis, capillary melting point, polarized hot‐stage microscopy, and temperature dependent small‐angle X‐ray scattering (SAXS) and assign physicochemical relevance to the DSC thermograms. Several DSC thermal transitions are irreversible after the first heating cycle of a heat‐cool‐heat‐cool‐heat cycle. Interestingly, after the first heat cycle, the complex cool‐heat‐cool‐heat DSC thermograms were highly reproducible and exhibited 6 reversible exothermic‐endothermic conjugate pairs. SAXS identified 5 distinct mesophases at different temperatures with Phase C′ persisting to 250°C. MgSt maintained molecular ordering beyond 276°C and did not undergo a simple melting phenomena reported elsewhere. This research serves as a starting point to design heat‐treatment strategies to create more uniform MgSt starting material.

Comparative binder efficiency modeling of dry granulation binders using roller compaction

Abstract Roller compaction parameters’ impact on granules and tableting properties of coprocessed Avicel® DG [ADG], a physical mixture of the two components at the same composition present in ADG [PADCP], and microcrystalline cellulose and Kollidon® VA-64 Fine physical mixture [KVA64] was quantified by analysis of variance (ANOVA) and multivariate methods. Roller force, roller gap, and roller speed levels were selected for evaluation. A 33 full-factorial experimental design with three center points for roller force, roller gap, and roller speed was used. The response parameters studied were granule-to-fines (GF) ratio, compressibility index (CI), tablet thickness (TT), tablet friability (TF), tablet breaking force (TBF) and disintegration time (DT). A model acetaminophen tablet formulation was roller granulated and tableted at 10 kg scale. Principal component analysis of ADG and PADCP formulations were separated from KVA64 formulations, indicating different granule and tableting properties were binder dependent. This difference in binder performance was also confirmed by ANOVA. The ANOVA also showed that there were no statistical performance differences between coprocessed ADG and its comparable physical blend with the exception of TT. Principal component regression (PCR) analyses of ADG and PADCP revealed that these excipients exhibited a statistically significant negative effect on granules-to-fine (GF) ratio, TT, TBF, and DT. KVA64 demonstrated a positive effect on these parameters. The KVA64 physical mixture demonstrated an overall better performance and binding capability. This study strongly suggests that there is no performance advantage of coprocessed Avicel® DG when compared to a physical mixture of the two components at the same composition.