Studies of hydroxypropyl methylcellulose donut-shaped tablets

Geometry-Driven Fabrication of Mini-Tablets via 3D Printing: Correlating Release Kinetics with Polyhedral Shapes

The aim of this study was to fabricate mini-tablets of polyhedrons containing theophylline using a fused deposition modeling (FDM) 3D printer, and to evaluate the correlation between release kinetics models and their geometric shapes. The filaments containing theophylline, hydroxypropyl cellulose (HPC), and EUDRAGIT RS PO (EU) could be obtained with a consistent thickness through pre-drying before hot melt extrusion (HME). Mini-tablets of polyhedrons ranging from tetrahedron to icosahedron were 3D-printed using the same formulation of the filament, ensuring equal volumes. The release kinetics models derived from dissolution tests of the polyhedrons, along with calculations for various physical parameters (edge, SA: surface area, SA/W: surface area/weight, SA/V: surface area/volume), revealed that the correlation between the Higuchi model and the SA/V was the highest (R2 = 0.995). It was confirmed that using 3D- printing for the development of personalized or pediatric drug products allows for the adjustment of drug dosage by modifying the size or shape of the drug while maintaining or controlling the same release profile.

The Influence of Shape Parameters on Unidirectional Drug Release from 3D Printed Implants and Prediction of Release from Implants with Individualized Shapes

The local treatment of diseases by drug-eluting implants is a promising tool to enable successful therapy under potentially reduced systemic side effects. Especially, the highly flexible manufacturing technique of 3D printing provides the opportunity for the individualization of implant shapes adapted to the patient-specific anatomy. It can be assumed that variations in shape can strongly affect the released amounts of drug per time. This influence was investigated by performing drug release studies with model implants of different dimensions. For this purpose, bilayered model implants in a simplified geometrical shape in form of bilayered hollow cylinders were developed. The drug-loaded abluminal part consisted of a suitable polymer ratio of Eudragit® RS and RL, while the drug-free luminal part composed of polylactic acid served as a diffusion barrier. Implants with different heights and wall thicknesses were produced using an optimized 3D printing process, and drug release was determined in vitro. The area-to-volume ratio was identified as an important parameter influencing the fractional drug release from the implants. Based on the obtained results drug release from 3D printed implants with individual shapes exemplarily adapted to the frontal neo-ostial anatomy of three different patients was predicted and also tested in an independent set of experiments. The similarity of predicted and tested release profiles indicates the predictability of drug release from individualized implants for this particular drug-eluting system and could possibly facilitate the estimation of the performance of customized implants independent of individual in vitro testing of each implant geometry.

3D printing of bioactive materials for drug delivery applications

INTRODUCTION

Three-dimensional (3D) printing, also known as additive manufacturing (AM), is a modern technique/technology, which makes it possible to construct 3D objects from computer-aided design (CAD) digital models. This technology can be used in the progress of drug delivery systems, where porosity has played important role in attaining an acceptable level of biocompatibility and biodegradability with improved therapeutic effects. 3D printing may also provide the user possibility to control the dosage of each ingredient in order to a specific purpose, and makes it probable to improve the formulation of drug delivery systems.

AREAS COVERED

This article covers the 3D printing technologies, bioactive materials including natural and synthetic polymers as well as some ceramics and minerals and their roles in drug delivery systems.

EXPERT OPINION

This technology is feasible to fabricate drug products by incorporating multiple drugs in different parts in such a mode that these drugs can release from the section at a predetermined rate. Furthermore, this 3D printing technology has the possible to transform personalized therapy to various age-groups by design flexibility and precise dosing. In recent years, the potential use of this technology can be realized in a clinical situation where patients will acquire individualized medicine as per their require.

Polyethylene oxide and its controlled release properties in hydrophilic matrix tablets for oral administration

Polymers are excipients that modify the rate of drug release from pharmaceutical dosage forms. Hydrophilic polymer-based controlled drug delivery system is more advantageous as compared to the conventional delivery system as it reduces the dosing frequency, improves therapeutic efficacy, reduces side-effects, and probably enhances patient compliance. Polyethylene oxide (PEO), a nonionic hydrophilic polymer, is one of the most widely used polymers for extending the drug release. This review mainly focuses on the PEO marketed by, but not limited to, The Dow Chemical Company under the trade name of POLYOX^TM. It is commercially available polyethylene oxide polymer existing in various molecular weight and viscosity grades depending upon the application. This study essentially discusses chemistry, physicochemical properties, and the impact of formulation and processing variables on the release of drug from hydrophilic PEO matrix tablets. Moreover, it also summarizes the stability, patents, and regulatory perspectives of POLYOX that can further influence the future developments of controlled release dosage forms.

Basit A. 3D Printing of Tunable Zero-Order Release Printlets

Zero-order release formulations are designed to release a drug at a constant rate over a prolonged time, thus reducing systemic side effects and improving patience adherence to the therapy. Such formulations are traditionally complex to manufacture, requiring multiple steps. In this work, fused deposition modeling (FDM) 3D printing was explored to prepare on-demand printlets (3D printed tablets). The design includes a prolonged release core surrounded by an insoluble shell able to provide zero-order release profiles. The effect of drug loading (10, 25, and 40% w/w paracetamol) on the mechanical and physical properties of the hot melt extruded filaments and 3D printed formulations was evaluated. Two different shell 3D designs (6 mm and 8 mm diameter apertures) together with three different core infills (100, 50, and 25%) were prepared. The formulations showed a range of zero-order release profiles spanning 16 to 48 h. The work has shown that with simple formulation design modifications, it is possible to print extended release formulations with tunable, zero-order release kinetics. Moreover, by using different infill percentages, the dose contained in the printlet can be infinitely adjusted, providing an additive manufacturing route for personalizing medicines to a patient.

Polymers for Extrusion-Based 3D Printing of Pharmaceuticals: A Holistic Materials-Process Perspective

Three dimensional (3D) printing as an advanced manufacturing technology is progressing to be established in the pharmaceutical industry to overcome the traditional manufacturing regime of 'one size fits for all'. Using 3D printing, it is possible to design and develop complex dosage forms that can be suitable for tuning drug release. Polymers are the key materials that are necessary for 3D printing. Among all 3D printing processes, extrusion-based (both fused deposition modeling (FDM) and pressure-assisted microsyringe (PAM)) 3D printing is well researched for pharmaceutical manufacturing. It is important to understand which polymers are suitable for extrusion-based 3D printing of pharmaceuticals and how their properties, as well as the behavior of polymer-active pharmaceutical ingredient (API) combinations, impact the printing process. Especially, understanding the rheology of the polymer and API-polymer mixtures is necessary for successful 3D printing of dosage forms or printed structures. This review has summarized a holistic materials-process perspective for polymers on extrusion-based 3D printing. The main focus herein will be both FDM and PAM 3D printing processes. It elaborates the discussion on the comparison of 3D printing with the traditional direct compression process, the necessity of rheology, and the characterization techniques required for the printed structure, drug, and excipients. The current technological challenges, regulatory aspects, and the direction toward which the technology is moving, especially for personalized pharmaceuticals and multi-drug printing, are also briefly discussed.

Patient acceptability of 3D printed medicines

Patient-centric medicine is a derivative term for personalised medicine, whereby the pharmaceutical product provides the best overall benefit by meeting the comprehensive needs of the individual; considering the end-user from the beginning of the formulation design process right through development to an end product is a must. One way in which to obtain personalised medicines, on-site and on-demand is by three-dimensional printing (3DP). The aim of this study was to investigate the influence of the shape, size and colour of different placebo 3D printed tablets (Printlets™) manufactured by fused deposition modelling (FDM) 3DP on end-user acceptability regarding picking and swallowing. Ten different printlet shapes were prepared by 3DP for an open-label, randomised, exploratory pilot study with 50 participants. Participant-reported outcome (PRO) and researcher reported outcome (RRO) were collected after picking and swallowing of selected printlet geometries including sphere, torus, disc, capsule and tilted diamond shapes. The torus printlet received the highest PRO cores for ease of swallowing and ease of picking. Printlets with a similar appearance to conventional formulations (capsule and disc shape) were also found to be easy to swallow and pick which demonstrates that familiarity is a critical acceptability attribute for end-users. RRO scores were in agreement with the PRO scores. The sphere was not perceived to be an appropriate way of administering an oral solid medicine. Smaller printlet sizes were found to be preferable; however it was found that the perception of size was driven by the type of shape. Printlet colour was also found to affect the perception of the end-user. Our study is the first to guide the pharmaceutical industry towards developing patient-centric medicine in different geometries via 3DP. Overall, the highest acceptability scores for torus printlets indicates that FDM 3DP is a promising fabrication technology towards increasing patient acceptability of solid oral medicines.

Design and evaluation of novel barrier layer technologies for controlling venlafaxine hydrochloride release from tablet dosage form

CONTEXT

Venlafaxine Hydrochloride (VH) is a highly soluble and highly permeable antidepressant compound. Thus controlling VH release from tablet dosage form over a prolonged period is a challenge.

OBJECTIVE

The objective of this work was to study the effect of various barrier layer formulation compositions, its orientations and manufacturing technology on release profile of highly soluble VH.

MATERIALS AND METHODS

Different barrier compositions and orientations were established on the same extended release formulations of VH using compression as well as film coating technologies. Barrier effectiveness in reducing the VH release was verified through in vitro dissolution studies.

RESULTS AND DISCUSSION

The "belly band" portion of the tablets was successfully oriented in different ways to develop bilayer as well as trilayer tablets. The compression technology had substantially reduced the VH release up to 16% in various compositions and orientation as compared to core tablet. The film coating technology had reduced the VH release up to 14% effectively; thereby shifting the dissolution curve to downside.

CONCLUSION

The explored "belly band" portion of the tablets had reduced the VH release substantially. These innovatively created different barrier orientation technologies hold the great promise of commercialization in future.

Oral drug delivery systems comprising altered geometric configurations for controlled drug delivery

Recent pharmaceutical research has focused on controlled drug delivery having an advantage over conventional methods. Adequate controlled plasma drug levels, reduced side effects as well as improved patient compliance are some of the benefits that these systems may offer. Controlled delivery systems that can provide zero-order drug delivery have the potential for maximizing efficacy while minimizing dose frequency and toxicity. Thus, zero-order drug release is ideal in a large area of drug delivery which has therefore led to the development of various technologies with such drug release patterns. Systems such as multilayered tablets and other geometrically altered devices have been created to perform this function. One of the principles of multilayered tablets involves creating a constant surface area for release. Polymeric materials play an important role in the functioning of these systems. Technologies developed to date include among others: Geomatrix(®) multilayered tablets, which utilizes specific polymers that may act as barriers to control drug release; Procise(®), which has a core with an aperture that can be modified to achieve various types of drug release; core-in-cup tablets, where the core matrix is coated on one surface while the circumference forms a cup around it; donut-shaped devices, which possess a centrally-placed aperture hole and Dome Matrix(®) as well as "release modules assemblage", which can offer alternating drug release patterns. This review discusses the novel altered geometric system technologies that have been developed to provide controlled drug release, also focusing on polymers that have been employed in such developments.

Novel drug delivery devices for providing linear release profiles fabricated by 3DP

Novel doughnut-shaped multi-layered drug delivery devices (DDDs) were developed with local variations of the drug and release-retardant material for providing linear release profiles. Based on computer-aided design models, different DDDs containing acetaminophen as a model drug, hydroxypropyl methylcellulose as matrix and ethyl cellulose (EC) as a release-retardant material were prepared automatically using a three-dimensional printing (3DP) system. In vitro dissolution assays demonstrated that all the 3DP DDDs had with different diameters, heights, concentrations of EC and central hole diameters were able to give linear release profiles. Morphological and erosion studies showed that acetaminophen was released through a simultaneous surface erosion process involving the outer peripheries and inner apertures. The barrier layers on both bases of DDDs had good adhesion strength with the drug-contained regions and offered consistent release retardation for the whole duration of the dissolution process. The release time periods of the DDDs were dependent on the annular thicknesses or the passes of binder solution containing a release-retardant material. The dosage of the DDD can be adjusted independently by changing the heights of the DDDs. Thus, 3DP is capable of offering novel strategies for developing DDDs with complex design features for desired drug release profiles.

A novel compression-coated doughnut-shaped tablet design for zero-order sustained release

A novel coated doughnut-shaped tablet is evaluated as to its ability to be manufactured in a reproducible manner, and as to whether it releases model drugs at a zero-order rate. The doughnut-shaped tablets were compressed using specially designed punches, which make automated production feasible. In the preliminary part of the experiment, HPMC K15M mixed with gelatin was found to be the most suitable coating tablet material with respect to its disintegration and adherence properties. The adherence of the coating tablet to ibuprofen cores was not optimal, so different concentrations of gelatin, to act as a plasticiser and enhance adherence, were further investigated. Friability results of the coated doughnut-shaped tablet indicate that coating tablets containing 20% and 30% gelatin had a percentage weight losses of less than 1% after 100 revolutions in a Roche friabilator. For all the concentrations of gelatin, the granule blends had angle of repose values in the range of 22.01-17.8 degrees. The compressibility factor, as measured from the slopes of the natural logarithm of compressional force versus crushing strength, were 121.91 +/- 2.36, 132.64 +/- 3.60, and 88.54 +/- 11.52 for the coating tablet granules containing 10%, 20%, and 30% gelatin in HPMC K15M, respectively. The composition of the coating tablet did not affect the rate of release of both caffeine and ibuprofen from the coated doughnut-shaped tablets. The coatings also adhered to the core tablets for the entire duration of the release of the drugs.

Modulation of combined-release behaviors from a novel “tablets-in-capsule system”

A multifunctional and multiple unit system, which contains versatile mini-tablets in a hard gelation capsule, is developed by preparing Rapid-release Mini-Tablets (RMTs), Sustained-release Mini-Tablets (SMTs), Pulsatile Mini-Tablets (PMTs), and Delayed-onset Sustained-release Mini-Tablets (DSMTs), each with various lag times of release. Based on the combinations of mini-tablets, multiplied pulsatile drug delivery system (DDS), site-specific DDS, slow/quick DDS, quick/slow DDS, and zero-order DDS could be obtained. Velocity-time curve, instead of the cumulative percentage drug release profile, is plotted. The nonlinear least square model fit program is applied to process the velocity data of dissolution. The test curves coincided with the theoretical curves from simple summation of v-t equations of individual mini-tablets. Therefore, the programmed DDS can be predicted by adding the v-t equations of various mini-tablets to calculate the theoretical equations and be implemented.

Investigation of the effect of tablet surface area/volume on drug release from hydroxypropylmethylcellulose controlled-release matrix tablets

The purpose of this study was to investigate the influence of tablet surface area/volume (SA/Vol) on drug release from controlled-release matrix tablets containing hydroxypropylmethylcellulose (HPMC). Soluble drugs (promethazine HCl, diphenhydramine HCl, and propranolol HCl) were utilized in this study to give predominantly diffusion-controlled release. Drug release from HPMC matrix tablets with similar values of SA/Vol was comparable within the same tablet shape (i.e., flat-faced round tablets) and among different shapes (i.e., oval, round concave, flat-faced beveled-edge, and flat-faced round tablets). Tablets having the same surface area but different SA/Vol values did not result in similar drug release; tablets with larger SA/Vol values hadfaster release profiles. Utility of SA/Vol to affect drug release was demonstrated by changing drug doses, and altering tablet shape to adjust SA/Vol. When SA/Vol was held constant, similar release profiles were obtained with f2 metric values greater than 70. Thus, surface area/volume is one of the key variables in controlling drug release from HPMC matrix tablets. Proper use of this variable has practical application by formulators who may need to duplicate drug release profiles from tablets of different sizes and different shapes.