Patient Acceptability and Preferences for Solid Oral Dosage Form Drug Product Attributes: A Scoping Review.

Background: There is no consistent framework for patient-centric drug product design, despite the common understanding that drug product acceptability and preferences influence adherence and, therefore, drug product effectiveness. The aim of this review was to assess current understanding of patient acceptability and preferences for solid oral dosage form (SODF) drug product attributes, and the potential impact of these attributes on patient behaviors and outcomes. Patients and Methods: A scoping review was conducted. Embase, Ovid MEDLINE®, and PubMed® were searched for full-text articles published between January 2013 and May 2023. Following screening and assessment against predefined inclusion criteria, data were analyzed thematically. Results: Nineteen studies were included. Four overarching domains of drug product attributes were identified and summarized in a framework: appearance, swallowability, palatability, and handling. Each domain was informed by specific drug product attributes: texture, form, size, shape, color, marking, taste, mouthfeel, and smell. The most frequently studied domains were swallowability and appearance, while the most studied attributes were size, shape, and texture. Smell, marking, and mouthfeel were the least studied attributes. Texture intersected all domains, while form, shape, and size intersected appearance, swallowability, and handling. Swallowability and size appeared to be the key domain and attribute, respectively, to consider when designing drug products. Few studies explored the impact of drug product attributes on behaviors and outcomes. Conclusion: While existing studies of drug product attributes have focused on appearance and swallowability, this review highlighted the importance of two less well-understood domains-palatability and handling-in understanding patients' acceptability and preferences for SODF drug products. The framework provides a tool to facilitate patient-centric design of drug products, organizing and categorizing physical drug product attributes into four overarching domains (appearance, swallowability, palatability, and handling), encouraging researchers to comprehensively assess the impact of drug product attributes on patient acceptability, preferences, and outcomes.

Medicines come in a variety of types and forms. These include tablets and capsules. Factors, such as the size and shape of tablets, can affect how people take medicines. However, patients are rarely involved in designing the medicines that they take. In this study, researchers summarized 19 studies published between 2013 and 2023. They wanted to understand how different factors, like size and shape, affect patients' preferences, ability, and willingness to take medicines. Researchers focused on the "physical" aspects of medicines and found 4 common themes: 1) what they look like (appearance), 2) how easy they are to swallow (swallowability), 3) how they taste and feel in the mouth (palatability), and 4) how easy they are to handle (handling). Eight factors were also found: color, markings, shape, size, smell, taste, texture, and how a medicine feels in the mouth (mouthfeel). Most studies focused on what medicines look like and how easy they are to swallow. The factors that researchers mostly looked at were the size, shape, and texture of medicines. The design of medicines can impact patients of different ages, though there may be specific needs for certain groups of patients, including children, older adults, and people with certain diseases. Patient input should become a part of future medicines design to ensure their acceptability.

Excipient Taxonomy for the 21st Century.

The performance of pharmaceutical dosage forms relies heavily on the characteristics of the excipients that are incorporated into the drug product during the manufacturing process. Therefore, it is imperative that formulators are able to accurately and completely specify the key chemical and physical properties of those excipients. Current approaches to describing excipients are outdated and inadequate for the needs of the 21st century and in this article we highlight the benefits of a more systematic and comprehensive approach to specifying and controlling excipient properties. We hope that this will prompt the users, suppliers, and manufacturers of excipients to take a careful look at current approaches and develop tangible proposals for attaining an enhanced future state.

Binary isobaric phase diagrams of stearyl alcohol-poloxamer 407 formulations in the molten and solid state.

Multiparticulate formulations allow for the design of specialized pharmaceutical dosage forms that cater to the needs of a wide range of patient demographics, such as pediatric and geriatric populations, by affording control over the release rate and facilitating the formulation of fixed-dose combination drugs. Melt spray-congealing (MSC) is a method for preparing multiparticulate dosage forms from a suspension or solid solution of active pharamaceutical ingredients (API) and a molten carrier matrix. Stearyl alcohol and poloxamer 407 mixtures are widely used as carrier matrices in MSC microsphere formulations. In this report, the phase equilibria of stearyl alcohol-poloxamer 407 mixtures were investigated by generating binary phase diagrams of composition, i.e. weight/weight percent of poloxamer 407 in stearyl alcohol, and temperature in the molten form and the solid state. The phase equilibria of the molten state were characterized by 1H NMR measurements. The miscibility curves of stearyl alcohol-poloxamer 407 molten mixtures revealed that stearyl alcohol and poloxamer 407 are not miscible in all proportions and that miscibility substantially increases with temperature. The phase equilibria of the solid state were characterized by DSC and PXRD experiments. The phase diagrams of the solid state indicate that stearyl alcohol and poloxamer 407 crystallize and melt separately and, thus, do not form a eutectic or a single phase. The phases equilibria of the bulk mixtures were compared to the phases observed in placebo MSC microspheres and it was determined that the microspheres consist of a mixture of thermodynamically stable and metastable stearyl alcohol crystals immediately after manufacture.

The Wall Friction Properties of Pharmaceutical Powders, Blends, and Granulations.

Data from wall friction testing and physical property characterization of over 100 pharmaceutical powders, blends, and granulations have been analyzed. The analyses focused on data for stainless steel surfaces with the most common finishes for pharmaceutical powder processing equipment, either a 2B cold rolled mill finish or an electropolished 2B surface. Active pharmaceutical ingredients exhibited the highest friction against these surfaces, whereas active granulations exhibited the least friction. The typical (median) wall friction angle for an active blend on 2B stainless steel was 22° versus 18° for an active granulation. Typical wall friction values on electropolished 2B surfaces were about 17° and 12° for active blends and granulations, respectively. Blends typically exhibited larger wall friction angles than the granulations suggesting that simple blends will usually require hoppers or bins with steeper walls to achieve mass flow. Lower wall friction angles were consistently observed against the smoother electropolished 2B surface, and, thus, the wall surface finish should be considered when designing bins and hoppers for use with pharmaceutical powders. The wall friction angles of blends and granulations did not show any definite trend as the percentage of active pharmaceutical ingredient increased.

Predicting the Crystallization Propensity of Drug-Like Molecules.

Predicting the crystallization propensity of drug-like molecules is one of the most significant challenges facing pharmaceutical scientists today. Despite the importance of being able to understand what structural features of a molecule (polarity, molecular size, etc.) and which experimental conditions (temperature, concentration, etc.) permit a molecule to crystallize, there has been very little published work focused on this topic. This commentary provides a short overview of recent progress in this area and points to potential experimental and computational approaches that might be used in the future.

A combined experimental and numerical approach to explore tribocharging of pharmaceutical excipients in a hopper chute assembly.

Electrostatic charging via contact electrification or tribocharging refers to the process of charge transfer between two solid surfaces when they are brought into contact with each other and separated. Charging of continuous particulate flows on solid surfaces is poorly understood and has often been empirical. This study aims toward understanding the tribocharging of pharmaceutical excipients using a simplified geometry of unidirectional flow in a hopper-chute assembly. Assuming electron transfer to be the dominant mechanism of electrification, a triboelectric series was generated using work functions estimated from quantum chemical calculations. A 3D-DEM model has been developed employing charge transfer and electrostatic forces. Using numerical simulations, the charge accumulation for an assemblage of particles during flow was determined under different conditions. To theoretically analyze the process of charging, parametric studies affecting powder flow have been investigated. A higher specific charge was observed at larger friction coefficients and lower restitution coefficients. The results obtained from the simulation model reinforce the collisional nature of triboelectrification. The simulation results revealed similar trends to experimental observations. However, to enable a priori prediction the model needs to be tested for additional materials or extended to other process operations.

Ultrasonic approach for viscoelastic and microstructure characterization of granular pharmaceutical tablets.

The mechanical properties of a solid dosage, defined by its granular micro-structure and geometry, play a key role in its dissolution profile and performance. An ultrasonic method for extracting the viscoelastic material properties and granular structure of drug tablet compacts is introduced and its utility is demonstrated for tablet compacts made of microcrystalline cellulose (MCC), lactose monohydrate, and sodium starch glycolate as well as magnesium stearate as lubricant. The approach is based on the effect of viscoelasticity and internal micro-structures on the frequency-dependent attenuation of an ultrasonic wave propagating in a granular medium. The models for viscoelastic (a two-parameter Zener model) and scattering attenuation (Rayleigh model) mechanisms are employed. The material parameters including viscoelastic and scattering parameters (average Young's modulus, stress and strain relaxation time constants, and the Rayleigh scattering material parameter) and grain size distribution with a known distribution profile are extracted by an optimization algorithm based on the least square method. The results also indicate good agreement between experimentally and computationally determined phase and group velocities in compacted samples. It is found that the effects of both attenuation mechanisms are present and the extracted grain size distribution parameters are in good agreement with the optically determined values.

How do formulation and process parameters impact blend and unit dose uniformity? Further analysis of the product quality research institute blend uniformity working group industry survey.

Responses from the second Product Quality Research Institute (PQRI) Blend Uniformity Working Group (BUWG) survey of industry have been reanalyzed to identify potential links between formulation and processing variables and the measured uniformity of blends and unit dosage forms. As expected, the variability of the blend potency and tablet potency data increased with a decrease in the loading of the active pharmaceutical ingredient (API). There was also an inverse relationship between the nominal strength of the unit dose and the blend uniformity data. The data from the PQRI industry survey do not support the commonly held viewpoint that granulation processes are necessary to create and sustain tablet and capsule formulations with a high degree of API uniformity. There was no correlation between the blend or tablet potency variability and the type of process used to manufacture the product. Although it is commonly believed that direct compression processes should be avoided for low API loading formulations because of blend and tablet content uniformity concerns, the data for direct compression processes reported by the respondents to the PQRI survey suggest that such processes are being used routinely to manufacture solid dosage forms of acceptable quality even when the drug loading is quite low.

Ultrasonic real-time in-die monitoring of the tablet compaction process-a proof of concept study.

The mechanical properties of a drug tablet can affect its performance (e.g., dissolution profile and its physical robustness. An ultrasonic system for real-time in-die tablet mechanical property monitoring during compaction has been demonstrated. The reported set-up is a proof of concept compaction monitoring system which includes an ultrasonic transducer mounted inside the upper punch of the compaction apparatus. This upper punch is utilized to acquire ultrasonic pressure wave phase velocity waveforms and extract the time-of-flight of pressure waves travelling within the compact at a number of compaction force levels during compaction. The reflection coefficients for the waves reflecting from punch tip-powder bed interface are extracted from the acquired waveforms. The reflection coefficient decreases with an increase in compaction force, indicating solidification. The data acquisition methods give an average apparent Young's moduli in the range of 8-20 GPa extracted during the compaction and release/decompression phases in real-time. A monitoring system employing such methods is capable of determining material properties and the integrity of the tablet during compaction. As compared to the millisecond time-scale dwell time of a typical commercial compaction press, the micro-second pulse duration and ToF of an acoustic pulse are sufficiently fast for real-time monitoring.

Effect of particle size on energy dissipation in viscoelastic granular collisions.

We analyze the scaling properties of the Hertz-Kuwabara-Kono (HKK) model, which is commonly used in numerical simulations to describe the collision of macroscopic noncohesive viscoelastic spherical particles. Parameters describing the elastic and viscous properties of the material, its density, and the size of the colliding particles affect the restitution coefficient ɛ and collision time τ only via appropriate rescaling but do not change the shape of ɛ(v) and τ(v) curves, where v is the impact velocity. We have measured the restitution coefficient experimentally for relatively large (1 cm) particles of microcrystalline cellulose to deduce material parameters and then to predict collision properties for smaller microcrystalline cellulose (MCC) particles by assuming the scaling properties of the HKK model. In particular, we demonstrate that the HKK model predicts the restitution coefficient of microscopic particles of about 100 µm to be considerably smaller than that of the macroscopic particles. In fact, the energy dissipation is so large that only completely inelastic collisions occur for weakly attractive particles. We propose a straightforward self-consistent extension to the Johnson-Kendall-Roberts (JKR) model to include dissipative forces and discuss the implications of our findings for the behavior of experimental powder systems.

Acoustic assessment of mean grain size in pharmaceutical compacts.

An ultrasonic non-destructive technique for the microstructure length-scale characterization of solid dosage pharmaceutical tablets is presented. The technique is based on the relationship between the attenuation of longitudinal ultrasonic elastic waves and the size of micro-structural features in the tablet material. In the reported experiments, the ultrasonic attenuation in microcrystalline cellulose (MCC)-lactose monohydrate (LMH) blended pharmaceutical compacts is measured by means of two pitch-catch experiments. The frequency dependent attenuation coefficient for the MCC-LMH compacts is then related to the mean grain diameter for each compact. For verification purposes, the mean grain diameter of the compacts was also established using micro-scale X-ray computerized tomography (MicroXCT). The mean grain diameters established by both routines agree well, and support the efficacy of the ultrasonic attenuation technique. The microstructure of a pharmaceutical compact (i.e., grain sizes and micro-feature size distribution) has been shown to have a profound effect on its mechanical properties, namely hardness, porosity, and mass density distribution, and in turn, can critically impact the dissolution profile and structural integrity of a compact. The ultrasonic technique presented provides a non-destructive and rapid method for determining the mean grain diameter size for powder compacts, thus providing a more timely and cost-effective method, compared to traditional techniques, of characterizing a compact's internal microstructure.

Discrete element method (DEM) simulations of stratified sampling during solid dosage form manufacturing.

Discrete element model (DEM) simulations of the discharge of powders from hoppers under gravity were analyzed to provide estimates of dosage form content uniformity during the manufacture of solid dosage forms (tablets and capsules). For a system that exhibits moderate segregation the effects of sample size, number, and location within the batch were determined. The various sampling approaches were compared to current best-practices for sampling described in the Product Quality Research Institute (PQRI) Blend Uniformity Working Group (BUWG) guidelines. Sampling uniformly across the discharge process gave the most accurate results with respect to identifying segregation trends. Sigmoidal sampling (as recommended in the PQRI BUWG guidelines) tended to overestimate potential segregation issues, whereas truncated sampling (common in industrial practice) tended to underestimate them. The size of the sample had a major effect on the absolute potency RSD. The number of sampling locations (10 vs. 20) had very little effect on the trends in the data, and the number of samples analyzed at each location (1 vs. 3 vs. 7) had only a small effect for the sampling conditions examined. The results of this work provide greater understanding of the effect of different sampling approaches on the measured content uniformity of real dosage forms, and can help to guide the choice of appropriate sampling protocols.

The coefficient of restitution of some pharmaceutical tablets/compacts.

When tablets collide during manufacturing and handling operations they rebound with a force and velocity that is determined by the collision conditions and the properties of the materials. This collision-rebound behavior of solid bodies can be described using a parameter known as the "coefficient of restitution" (CoR). In this work, the CoR of a range of pharmaceutical tablets/compacts is measured using a simple "drop test", and the influences of material properties (elastic modulus, solid fraction, etc.) and collision conditions (substrate, energy/speed, etc.) are investigated. The compacted pharmaceutical materials have CoR values that range from 0.4 to 0.9, and the CoR generally increases with increasing compact solid fraction. The CoR varies with the mechanical properties of both colliding bodies and is lower for more plastic collisions and higher for elastic collisions. This behavior is consistent with theories developed for non-pharmaceutical solids, and can be predicted provided that the elasticity and yield stress of the samples are treated as porosity dependent parameters. In this case, the CoR varies with the impact velocity nearly raised to the fourth root. Having established a simple and reproducible test for the CoR of pharmaceutical compacts and tablets it should be possible to create more accurate engineering models and computer simulations of tablet manufacturing and packaging operations.

Correlating particle hardness with powder compaction performance.

Assessing particle mechanical properties of pharmaceutical materials quickly and with little material can be very important to early stages of pharmaceutical research. In this study, a wide range of pharmaceutical materials were studied using atomic force microscopy (AFM) nanoindentation. A significant amount of particle hardness and elastic modulus data were provided. Moreover, powder compact mechanical properties of these materials were investigated in order to build correlation between the particle hardness and powder compaction performance. It was found that the materials with very low or high particle hardness most likely exhibit poor compaction performance while the materials with medium particle hardness usually have good compaction behavior. Additionally, the results from this study enriched Hiestand's special case concept on particle hardness and powder compaction performance. This study suggests that the use of AFM nanoindentation can help to screen mechanical properties of pharmaceutical materials at early development stages of pharmaceutical research.

The coefficient of rolling resistance (CoRR) of some pharmaceutical tablets.

Experiments have been conducted to measure the coefficient of rolling resistance (CoRR) of some pharmaceutical tablets and several common materials, such as glass beads and steel ball bearings. CoRR values are required as inputs for discrete element method (DEM) models which can be used to model particulate flows and solid dosage form manufacturing processes. Until now there have been no CoRR data reported for pharmaceutical materials, and thus these new data will help to facilitate more accurate modeling of pharmaceutical systems.

An investigation into the kinetic (sliding) friction of some tablets and capsules.

The kinetic (or sliding) friction of pharmaceutical tablets and capsules influences how they will behave during the conveying, coating, and packaging operations that are used for drug product manufacturing. In order to logically design equipment for manufacturing and packaging operations, and to simulate manufacturing and packaging performance (for example, using discrete or finite element modeling approaches), it is necessary to quantify the magnitude of the kinetic friction. In this work, the coefficient of kinetic friction of a range of pharmaceutical tablets and capsules has been measured for the first time using a pin-on-disk tribometer. Binary tablet-tablet contacts and the contacts between tablets or capsules and common equipment surfaces were studied. The range of the friction coefficients was large (between 0.00 and 0.74), and the values depended strongly on the identity of both contacting materials. Tablet-tablet contacts generally exhibited lower friction coefficients than tablet-polymer or tablet-metal contacts. Polymeric surfaces were generally less frictional than metal surfaces, even those that were highly polished. Tablet coatings appeared to have a marked effect on the kinetic friction coefficient between tablets and equipment surfaces, with the hardest coatings tending to be the least frictional. The surface roughness of the tablets and contacting surfaces did not contribute to the coefficient of kinetic friction in a consistent manner. The implications of the results for the design of conveying, processing and packaging operations are discussed.