Multi-Analytical Framework to Assess the In Vitro Swallowability of Solid Oral Dosage Forms Targeting Patient Acceptability and Adherence

A lack of effective intervention in addressing patient non-adherence and the acceptability of solid oral dosage forms combined with the clinical consequences of swallowing problems in an ageing world population highlight the need for developing methods to study the swallowability of tablets. Due to the absence of suitable techniques, this study developed various in vitro analytical tools to assess physical properties governing the swallowing process of tablets by mimicking static and dynamic stages of time-independent oral transitioning events. Non-anatomical models with oral mucosa-mimicking surfaces were developed to assess the swallowability of tablets; an SLA 3D printed in vitro oral apparatus derived the coefficient of sliding friction and a friction sledge for a modified tensometer measured the shear adhesion profile. Film coat hydration and in vitro wettability was evaluated using a high-speed recording camera that provided quantitative measurements of micro-thickness changes, simulating static in vivo tablet–mucosa oral processing stages with artificial saliva. In order to ascertain the discriminatory power and validate the multianalytical framework, a range of commonly available tablet coating solutions and new compositions developed in our lab were comparatively evaluated according to a quantitative swallowability index that describes the mathematical relationship between the critical physical forces governing swallowability. This study showed that the absence of a film coat significantly impeded the ease of tablet gliding properties and formed chalky residues caused by immediate tablet surface erosion. Novel gelatin- and λ-carrageenan-based film coats exhibited an enhanced lubricity, lesser resistance to tangential motion, and reduced stickiness than polyvinyl alcohol (PVA)–PEG graft copolymer, hydroxypropyl methylcellulose (HPMC), and PVA-coated tablets; however, Opadry^® EZ possessed the lowest friction–adhesion profile at 1.53 a.u., with the lowest work of adhesion profile at 1.28 J/mm². For the first time, the in vitro analytical framework in this study provides a fast, cost-effective, and repeatable swallowability ranking method to screen the in vitro swallowability of solid oral medicines in an effort to aid formulators and the pharmaceutical industry to develop easy-to-swallow formulations.

Patient-Centric Medicine Design: Key Characteristics of Oral Solid Dosage Forms that Improve Adherence and Acceptance in Older People

Older people represent a very heterogeneous patient population and are the major user group of medication. Age-related changes mean that this population can encounter barriers towards taking medicines orally. The aim of this study was to investigate the characteristics of oral solid dosage forms that contribute to an age appropriate dosage design, with an aim to improve overall medication adherence and acceptance in older people. Fifty-two semistructured interviews were conducted with older people, informal (family) carers, and health and social care professionals. Formulation characteristics impacted three stages of the medication taking process: (1) medication identification and memorability, (2) medication handling and (3) swallowability. Small round tablets (≤7 mm) are least accepted amongst older people and their carers and had a negative impact on all stages. The use of bright, two-coloured preparations and interesting shapes improves identification and further aids memorability of indications and the timing of tablets. Palatability, while useful to enhance swallowability, also has an impact on the visual appeal and memorability of medication. Environmental, patient, medication and disease characteristics also determine preferences for formulation. Developing an age appropriate dosage design for older people, therefore, requires a holistic, patient-centric approach to improve adherence and acceptance.

Does the Formulation of Oral Solid Dosage Forms Affect Acceptance and Adherence in Older Patients? A Mixed Methods Systematic Review

OBJECTIVES

Age-related changes mean that the older population can encounter barriers toward taking medication orally. Further work is needed to identify the characteristics of oral solid dosage forms that will improve patient acceptance and adherence. The aim of this systematic review was to identify if and how formulation aspects of oral solid dosage forms affect acceptance and adherence in older people.

DESIGN

Mixed methods systematic review using a data-based convergent synthesis design.

SETTING AND PARTICIPANTS

Articles were selected if they included participants aged 60 years and older, or included health care professionals, social care professionals, and informal carers of patients aged 60 years and older.

METHODS

A systematic search of the following databases was undertaken: Web of Science, MEDLINE, Scopus, and The Cochrane Databases. The search of databases was supplemented by a search of gray literature, and reference lists of included papers were manually searched.

RESULTS

A total of 16 studies were included in the final synthesis. Three themes were generated from the thematic analysis: (1) dimensions, (2) palatability, and (3) appearance. The dimensions and palatability are often modified to improve swallowability by breaking tablets in half or taste masking with food. Polypharmacy can lead to patients using the appearance to identify tablets; however, this can lead to confusion when products appear similar. No study was identified that explored formulation characteristics across all 3 categories directly in the older population.

CONCLUSION AND IMPLICATIONS

Manufacturers should take into account practical problems older people may encounter when considering the dimensions, palatability, and appearance of the final drug product. These characteristics should be optimized to aid visual identification and swallowability. Medical providers and pharmacists have an important role in ensuring that these patient-centric drug products are prescribed and dispensed appropriately so that patients receive the most suitable formulation.

Robustness of barrier membrane coated metoprolol tartrate matrix tablets: Drug release evaluation under physiologically relevant in vitro conditions

Robust in vitro drug release behavior is an important feature of extended release (ER) hydrophilic matrix formulations for accurate prediction of in vivo drug release. In this study, ER hydrophilic matrix tablets of metoprolol tartrate were formulated using a high viscosity grade of hypromellose as a rate-limiting polymer. Expectedly, this formulation showed an undesirable initial burst release followed by controlled drug release. Application of a barrier membrane (BM) coating of ethylcellulose with a pore former (hypromellose) resulted in the elimination of the burst effect. The aim of this study was to investigate the robustness of in vitro metoprolol release from BM-coated hydrophilic matrix tablets by simulating the physicochemical properties of gastrointestinal fluids and mechanical stress in the fasted- and fed state human gastrointestinal (GI) tract. Uncoated and BM-coated matrices were subjected to various dissolution studies simulating the varying pH conditions and additional physicochemical parameters, and the mechanical stress that can be caused by GI motility during both fasted and fed state GI passage. The BM-coated formulation showed robust drug release without an initial burst in all test scenarios. BM-coated matrix formulations thus represent a very promising approach for obtaining a highly controlled and robust drug release from oral ER formulations.

Development of micro-fibrous solid dispersions of poorly water-soluble drugs in sucrose using temperature-controlled centrifugal spinning

Solid dispersion technology represents a successful approach to addressing the bioavailability issues caused by the low aqueous solubility of many Biopharmaceutics Classification System (BCS) Class II drugs. In this study, the use of high-yield manufacture of fiber-based dispersion is explored as an alternative approach to monolith production methods. A temperature-controlled solvent-free centrifugal spinning process was used to produce sucrose-based microfibers containing the poorly water-soluble drugs olanzapine and piroxicam (both BCS Class II); these were successfully incorporated into the microfibers and the basic characteristics of fiber diameter, glassy behavior, drug loading capacity and drug-sucrose interaction assessment were measured. Scanning electron microscopy revealed that bead-free drug-loaded microfibers with homogenous morphology and diameter in the range of a few micrometers were prepared using our process. Differential scanning calorimetric and X-ray diffraction analyses showed that both drug and carrier were present in the amorphous state in the microfibers, although in the case of piroxicam-loaded microfibers, the presence of small amounts of crystalline drug was observed under polarized light microscopy and in Fourier transform infrared spectra. Drug dissolution performance was evaluated under both sink and non-sink conditions and was found to be significantly enhanced compared to the corresponding crystalline physical mixtures and pure drugs, with evidence of supersaturation behavior noted under non-sink conditions. This study has demonstrated that microfiber-based dispersions may be manufactured by the centrifugal spinning process and may possess characteristics that are favorable for the enhanced dissolution and oral absorption of drugs.

Application of ethylcellulose coating to hydrophilic matrices: a strategy to modulate drug release profile and reduce drug release variability

Hydrophilic matrix tablets are commonly used for extended release dosage forms. For low aqueous-solubility drugs, there may be challenges in modulation of release profiles and achieving consistent release in physiological conditions. To evaluate potential formulation strategies, matrix tablets of a low-soluble drug, hydrochlorothiazide, were developed using hypromellose and two fillers of different solubility, lactose (soluble) or partially pregelatinized maize starch (partially soluble). Additionally, application of an insoluble barrier membrane, aqueous ethylcellulose coating system, and a hydrophilic pore former onto matrix tablets was evaluated. Drug release from uncoated matrix tablets was variable at different agitation rates. Evaluation of tablets in bio-relevant media using physiologically relevant residence time indicated variable and higher initial release rate for uncoated matrices containing lactose but more robust behavior for tablets containing partially pregelatinized starch. Such in vitro behavior may lead to erratic drug release in vivo, when comparing fed versus fasted conditions. Dissolution profiles from barrier membrane-coated tablets showed initial delay, followed by zero-order release kinetics, with reduction or elimination of variability compared to uncoated matrices. Such reduced variability may mitigate mechanical effects of post-prandial stomach. Effects of coating weight gain and inclusion levels of pore former were evaluated and found to be critical in achieving robust and stable release profiles.

Investigation of critical core formulation and process parameters for osmotic pump oral drug delivery

Push-pull osmotic pump (PPOP) tablets of a practically insoluble model drug were developed and the effect of various formulation and process parameters on tablet performance was evaluated in order to identify critical factors. The formulation factors such as the viscosity grade of polyethylene oxide as the primary polymer as well as the level and location of osmogen within the bilayer tablets led to a difference in performance of osmotic tablets and hence should be critically evaluated in the design of such dosage forms. Modification of granulation process, i.e., the granulating liquid composition or drying method of granules, did not impact the drug release from the osmotic tablets at the evaluated scale of this study. The influence of varying dose and aqueous solubility of other model drugs (i.e., theophylline, acetaminophen, and verapamil HCl) on the developed PPOP template was also investigated. Results showed that irrespective of the perceived complexity of development and manufacturing of osmotic pumps, the osmotic tablets in this study demonstrated a robust and yet flexible platform in accommodating different types of drug candidates, regardless of solubility, for the dose levels below 25% w/w of the pull layer formulation.

Investigation of the effects of hydroalcoholic solutions on textural and rheological properties of various controlled release grades of hypromellose

Hypromellose (hydroxypropyl methylcellulose, HPMC) matrices are widely used in the formulation of sustained release dosage forms. The integrity and performance of an HPMC matrix formulation depends on rapid hydration and gel formation upon ingestion. Due to the recent alert issued by the Food and Drug Administration regarding the potential negative influence of alcoholic beverages on extended release (ER) formulations, several researchers have evaluated the potential influence of hydroalcoholic media on drug release from ER dosage forms. It has been reported that HPMC matrix formulations do not show "dose dumping" in hydroalcoholic media. The purpose of this study was a fundamental investigation on the effect of hydroalcoholic solutions (0-40% v/v ethanol) on textural and rheological properties of different viscosity grades of neat HPMC, as the functional ingredient within a hydrophilic matrix. In general, hydroalcoholic solutions had little effect on gel formation and mechanical properties of hydrated compacts, while the rheological behavior of HPMC showed dependency on the ethanol content of such solutions.

Evaluation and comparison of physicomechanical characteristics of gelatin and hypromellose capsules

The aim of this study is evaluation and comparison of physical and mechanical properties of hypromellose and gelatin capsules. For this purpose, the empty and filled capsules of hypromellose and gelatin (size 4) were examined in regard with their physical and mechanical characteristics, employing textural analysis, and disintegration properties in various immersion fluids, utilizing a USP 28 disintegration apparatus. The results demonstrated that owing to their greater water permeability, gelatin capsules disintegrate much faster than hypromellose shells in all tested media. However, hypromellose capsules showed a more uniform pattern of dispersion in the disintegration fluids. As for mechanical properties, at ambient conditions, gelatin capsules appeared to be harder and stronger with less elasticity as compared with hypromellose shells. On the contrary, at an elevated temperature, gelatin capsules demonstrated lower resilience. This study shows that hypromellose capsules have excellent properties and are promising as far as regulatory, manufacturing, religious, and dietary issues are concerned.

Application of powder rheometer to determine powder flow properties and lubrication efficiency of pharmaceutical particulate systems

The objective of this study was to understand the behavior of particulate systems under different conditions of shear dynamics before and after granulation and to investigate the efficiency of powder lubrication. Three drug powders, metronidazole, colloidal bismuth citrate, and tetracycline hydrochloride, were chosen as model drugs representing noncohesive and cohesive powder systems. Each powder was individually granulated with microcrystalline cellulose and 5%PVP as a binder. One portion from each granulation was lubricated with different levels of magnesium stearate for 5 minutes. The powder characterization was performed on the plain powders, nonlubricated and lubricated granules using powder rheometer equipped with a helical blade rotating and moving under experimentally fixed set of parameters. The profiles of interaction during the force-distance measurements indicate that powder compresses, expands, and shears many times in a test cycle. Test profiles also clearly reveal existence of significant differences between cohesive and noncohesive powders. In all cases lubrication normalized the overall interactive nature of the powder by reducing peaks and valleys as observed from the profiles and reduced the frictional effect. The developed methods are easy to perform and will allow formulation scientists to better understand powder behavior and help in predicting potential impact of processing factors on particulate systems.

Release characterization of dimenhydrinate from an eroding and swelling matrix: selection of appropriate dissolution apparatus

The objective of this study was to evaluate the effect of various hydrodynamic conditions on drug release from an eroding and gel forming matrix. For this purpose, dimenhydrinate was formulated with hydroxypropyl methyl cellulose and polyethylene oxide into matrix tablets and the drug release in deionized water was evaluated spectrophotometrically, using multiple dissolution methods, namely, compendial USP 27-apparatus I-III, and a modified apparatus II (paddle over mesh). Various hydrodynamic conditions were examined at the agitation rates of 50 and 100 rpm for apparatus I and II, and 5 and 8 dpm for apparatus III. Similarity and difference factors were calculated using compendial apparatus II release data as reference. Among the methods, apparatus I showed the slowest initial release, while the release from apparatus III at 8 dpm was the highest among the methods. This was further compared via the dissolution half-times and calculation of the average release rate for each method. Based on the analysis of difference and similarity factors (f(1) and f(2)), the study clearly demonstrates the significance of hydrodynamics and the choice of a dissolution method and their respective effect on overall release profiles when erodible and swellable matrix systems are involved. Full surface exposure with insertion of mesh device in apparatus II may provide more realistic conditions especially when release data are to be used in developing IVIVCs.

A novel approach in the assessment of polymeric film formation and film adhesion on different pharmaceutical solid substrates

The purpose of this study was to evaluate the nature of film formation on tablets with different compositions, using confocal laser scanning microscopy (CLSM), and to measure film adhesion via the application of a novel "magnet probe test." Three excipients, microcrystalline cellulose (MCC), spray-dried lactose monohydrate, and dibasic calcium phosphate dihydrate, were individually blended with 0.5% magnesium stearate, as a lubricant, and 2.5% tetracycline HCl, as a fluorescent marker, and were compressed using a Carver press. Tablets were coated with a solution consisting of 7% hydroxypropyl methylcellulose (HPMC) phthalate (HP-55), and 0.5% cetyl alcohol in acetone and isopropanol (11:9). The nature of polymer interaction with the tablets and coating was evaluated using CLSM and a designed magnet probe test. CLSM images clearly showed coating efficiency, thickness, and uniformity of film formation, and the extent of drug migration into the film at the coating interfaces of tablets. Among the excipients, MCC demonstrated the best interface for both film formation and uniformity in thickness relative to lactose monohydrate and dibasic calcium phosphate dihydrate. The detachment force of the coating layers from the tablet surfaces, as measured with the developed magnet probe test, was in the order of MCC>lactose monohydrate>dibasic calcium phosphate dihydrate. It was also shown that the designed magnet probe test provides reliable and reproducible results when used for measurement of film adhesion and bonding strength.