Mini-tablets versus pellets as promising multiparticulate modified release delivery systems for highly soluble drugs

Ultra-high-resolution optical coherence tomography for the investigation of thin multilayered pharmaceutical coatings

Optical Coherence Tomography (OCT) has recently gained attention as a promising technology for in-line monitoring of pharmaceutical film-coating processes for (single-layered) tablet coatings and end-point detection with commercial systems. An increasing interest in the investigation of multiparticulate dosage forms with mostly multi-layered coatings below 20 µm final film thickness demands advancement in OCT technology for pharmaceutical imaging. We present an ultra-high-resolution (UHR-) OCT and investigate its performance based on three different multiparticulate dosage forms with different layer structures (one single-layered, two multi-layered) with layer thicknesses in a range from 5 to 50 µm. The achieved system resolution of 2.4 µm (axial) and 3.4 µm (lateral, both in air) enables the assessment of defects, film thickness variability and morphological features within the coating, previously unattainable using OCT. Despite the high transverse resolution, the provided depth of field was found sufficient to reach the core region of all dosage forms under test. We further demonstrate an automated segmentation and evaluation of UHR-OCT images for coating thicknesses, where human experts struggle using today's standard OCT systems.

Pluronic F-68 Montmorillonite As A Drug Delivery Vehicle For Extended Release Of Venlafaxine Hydrochloride

Short half-life and low bioavailability of Venlafaxine hydrochloride (VF), an antidepressant drug, necessitates the frequent administration of VF tablets in a day in order to maintain adequate drug concentration in blood plasma. This generates the need for the development of formulations which could prolong the release of VF and reduce the multiple dosages. The present work explores the combination of Montmorillonite (Mt) with Pluronic F-68 (PF-68) (OrganoMT) for oral delivery of VF. The effect of various parameters including pH of aqueous drug solution, contact time and initial drug concentration on drug loading capacity of OrganoMT has been studied. The synthesized OrganoMT-VF complexes were characterized by various suitable techniques. XRD studies indicated that the VF molecules were intercalated within the OrganoMT layers. In vitro release behavior of VF from OrganoMT-VF complexes shows an extended-release pattern for a period of 30 h and reaches upto 70% and 60% compared to pure VF having complete release time of 5.5 h and 3.5 h in simulated gastric and intestinal fluid respectively. Various kinetic models were employed to elucidate the drug release mechanism where the best fitting was obtained with Korsmeyer Peppas model. The results suggest the possibility of designing an oral extended controlled release formulation for VF to minimize its administration frequency thereby increasing the effectiveness of drug. This improves patient compliance by reducing the dose from 4 times in 24 h to once in 24 h.

Dose Titration of Solid Dosage Forms via FDM 3D-Printed Mini-Tablets

The robustness of 3D-printed mini-tablets as a platform to administer milligram dosages, intended for age-specific therapy, without the need of tablet splitting while maintaining similar release profiles, was investigated. Griseofulvin, as a model poorly water-soluble drug, and hydroxypropyl cellulose along with Kollicoat Protect as polymers were used to prepare filaments at 1–20% drug concentrations via hot-melt extrusion (HME). Higher drug concentrations served for testing the feasibility of a reduced number of mini-tablets to be administered. A reliable dose titration in the range 0.19–3.91 mg at a high accuracy (R2 of 0.999) was achieved through composite unit (multi-unit) mini-tablets. All mini-tablets produced had excellent content uniformity and their label claim values were within the acceptable range, proving that HME processing followed by 3D printing promotes content uniformity even for mini-tablets containing low drug doses (0.19 mg). Remarkably, the proposed approach allowed achieving similar drug release profiles via composite unit mini-tablets as well as single mini-tablets at high drug concentrations. In contrast, split tablets demonstrated different release behaviors, attributed to their size and shape differences. Overall, the distinct advantages of mini-tablets to provide dose flexibility while maintaining similar release profiles was demonstrated.

Design of Experiments as a Tool to Optimize the Process of Coating Minitablets with Commercial Gastro-Resistant Coating Mixtures

According to the Quality by Design (QbD) concept, Design of Experiment (DoE) was used to indicate critical process parameters and optimize the fluid bed coating of minitablets in a laboratory size batch. Full factorial design was employed to increase knowledge of the process for three kinds of minitablet (MT) cores using two commercial gastro-resistant coating mixtures. The statistical analysis showed that different critical process parameters were indicated for the tested minitablets: X3: the coating mixture flow rate for MTs with pantoprazole sodium and Eudragit L; X2: the product temperature; X3 and X4: the spraying pressure for MTs with pantoprazole sodium and Acryl Eze II; and X1 and X2: MTs with diclofenac sodium. Such differences were the result of features, such as the sub-coat, size, and mass of the cores and the core and coating mixture composition. No optimal parameters were found for any of the tested MT types. Therefore, DoE should be considered as a statistical tool to individually optimize the process for the product, equipment, and tested parameters. However, optimization of the fluid bed coating allowed us to predict the values of the process parameters necessary to obtain good-quality products. Therefore, fluid bed coating may be successfully used to obtain modified-release MTs of high quality after applying the statistical tool DoE.

Mini-tablets as technological strategy for modified release of morphine sulfate

The aim of this study was to use intelligent formulation design for development of mini-tablets for modified release of morphine sulfate. A formulation (F1) was proposed using the Hiperstart® software. Based on the suggested formulation, two other formulations (F2 and F3) were prepared: one for modified and another for immediate drug release. The powders were characterized as bulk and tapped density, Hausner's factor and compressibility index analyzes. Mini-tablets were directly compressed and characterized as hardness, friability, size, and weight variation. The in vitro drug release profile was carried out according to the apparatus 1 of USP. Formulations showed good flow properties, and the mini-tablets displayed characteristics according to the specified. In comparison to F3 (immediate release), F1 and F2 displayed slower drug release time, showing the efficiency of the matrix formed. F3 displayed 90% of drug released up to 10 min, while F1 and F2 required 240 min. The results highlight the importance to use intelligent formulation design for the development of improved mini-tablet matrices. Formulation F1 was found to be suitable for modified morphine sulfate release. Further studies with more formulations are necessary for production of optimized mini-tablets with suitable prolonged morphine sulfate release.

Dispensing of minitablets - Has the problem been resolved?

Recently, minitablets have been given extensive coverage in literature, as they are perfectly matched to the current therapy individualization trend. Within this scope, special attention is paid to minitablets that enable convenient drug intake for patients with swallowing problem. However, the packaging system, dispensing the necessary amount of drug units and safe administration still remain unsolved problems or are partially overlooked. Although there are many different approaches towards dosing tablets, only a few seem to be tailored to particularly small tablets. Moreover, none of these approaches meets all the user's expectations. This paper comprehensively elaborates and critically discusses the available dosing options like sachets, blisters, home electronic dispensing systems and minitablets manual dispensers. Additional tests have been also conducted to simulate the handling and dosing procedure with 2 mm diameter placebo minitablets. Despite many advantageous inventions, it has been revealed that further efforts are necessary to identify the optimal design that would allow to eliminate the shaking procedure, adjust cavities diameter or provide better protection against humidity. Nevertheless, the current trend may lead to individual therapy becoming more convenient, safe and reliable, especially in pediatric and geriatric patients.

Assessment of Mini-Tablets Coating Uniformity as a Function of Fluid Bed Coater Inlet Conditions

This study concerned the quality of mini-tablets’ coating uniformity obtained by either the bottom spray chamber with a classical Wurster distributor (CW) or a swirl distributor (SW). Mini-tablets with a diameter of 2.0, 2.5, and 3.0 mm were coated with hypromellose using two different inlet air distributors as well as inlet airflow rates (130 and 156 m³/h). Tartrazine was used as a colorant in the coating layer and the coating uniformity was assessed by spectrophotometric analysis of solutions obtained after disintegration of the mini-tablets (n = 100). Higher uniformity of coating material distribution among the mini-tablets was observed in the case of SW distributor, even for the biggest mini-tablets (d = 3.0 mm), with an RSD no larger than 5.0%. Additionally, coating thickness was evaluated by colorimetric analysis (n = 1000), using a scanner method, and expressed as a hue value. A high correlation (R = 0.993) between inter-tablet variability of hue and UV-Vis results was obtained. Mini-tablets were successfully coated in a fluid bed system using both a classical Wurster distributor as well as a swirl generator. However, regardless of the mini-tablets’ diameter, better film uniformity was achieved in the case of a distributor with a swirl generator.

Tableting of mini-tablets in comparison with conventionally sized tablets: A comparison of tableting properties and tablet dimensions

Mini-tablets are solid dosage forms with increasing interest for pharmaceutical industry due to clinical and biopharmaceutical benefits. But technological aspects on mini-tableting are not fully investigated. Therefore, the impact of punch size and tableting pressure for industrially relevant excipients like microcrystalline cellulose, lactose, isomalt and Ludiflash® are investigated using 8 and 11.28 mm punches for conventionally sized tablets and 1,2 and 3 mm punches for mini-tablets. For evaluation of the effect of tablet size on deformation behaviour and mechanical properties, compressibility, compactibility and tabletability plots are created and evaluated. Deformation behaviour is analysed by In-Die Heckel plot and modified Weibull function. Further, specific plastic energy (SPE) profiles are generated out of force-displacement plots. The effect of the adjustment of the aspect ratio towards 1 as in conventionally sized tablets on deformation behaviour and tabletability is analysed. The effect of tablet size on deformation behaviour mainly showed lower yield pressures for conventionally sized tablets, whereas comparable SPEs were obtained with all tablet sizes. Furthermore, mini-tablets indicate better compactibility, as (depending on the excipient) higher tensile strengths were obtained at lower solid fractions. However, no superior tabletability properties are obtained for mini-tablets compared to conventionally sized tablets.

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Mini-tablets show higher compactibility compared to conventionally sized tablets.

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Mini-tablets show specific plastic energy profiles similar to conventional tablets.

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There is no trend for better tabletability for mini-tablets or conventionally sized tablets.

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Highest yield pressures are obtained with mini-tablets.

Optimization of the coating process of minitablets in two different lab-scale fluid bed systems

The optimization of the coating process for minitablets is extremely important in fluidized bed systems, and allows knowledge acquisition about the process for modern multiparticulate forms. The coating of minitablets allows the development of modified-release pediatric drugs. In our study, 3-mm minitablets with pantoprazole were coated to obtain an enteric product. The experiments were designed to evaluate the quality of the enteric product by efficiency and quality of film coating. Four process parameters at two levels were examined, and 16 experiments for two different fluid bed systems in laboratory-scale batches were performed. During analysis, the critical parameters of inlet airflow rate (X1) and coating mixture flow rate (X3) in different fluid bed coaters were examined. The findings indicate that apparatus construction has a significant effect on the different process parameters. Despite the fact that statistical analysis is directly related to the tested conditions, it creates opportunity to anticipate certain problems while scaling up, and a possibility to minimize them.

Water-insoluble polymers as binders for pellet drug layering: Effect on drug release and performance upon compression

The objective of this study was to investigate the applicability of water-insoluble polymers as binders for pellet drug layering to extend the drug release. Carbamazepine was layered on sugar cores in fluidized bed coater using isopropanol (IPA):water solution or aqueous dispersion of ethylcellulose, polyvinyl acetate or ammonium-methylmethacrylate copolymer. Carbamazepine release was extended with all investigated water-insoluble polymers used as binder, without an additional coating layer. Drug release from pellets layered using IPA:water polymer solutions was dependent on polymer properties such as lipophilicity and pore-forming components, while from those layered with aqueous polymer dispersions, the release was dependent on the completeness of film formation during drug layering. Curing effect was observed only for pellets layered with Aquacoat® ECD and Eudragit® RS 30D. The drug release was not affected by compression when pellets were prepared with the flexible polymers Kollidon® SR or Kollicoat® SR 30D, however, it increased when brittle polymers such as ethylcellulose or Eudragit® RS were used. This problem could be minimized by using a higher amount of the binder, addition of a plasticizer or using polymers of higher viscosity grade. In conclusion, the use of water-insoluble polymers as binder for pellet drug layering is an effective tool to extend the drug release without additional coating step.

Premium ethylcellulose polymer based architectures at work in drug delivery

Premium ethylcellulose polymers are hydrophobic cellulose ether based biomaterials widely employed as biocompatible templates for the design of novel drug delivery systems. They are classified as United States Food and Drug Administration Generally-Recognized-As-Safe chemical substances and have been extensively utilized within the biomedical and pharmaceutical industries for over half a century. They have so far demonstrated the potential to modulate and improve the physiological performance of bioactives leading to the desired enhanced prophylactic and therapeutic outcomes. This review therefore presents a scholarly survey of inter-disciplinary developments focused on the functionalities of ethylcellulose polymers as biomaterials useful for the design of smart delivery architectures for relevant pharmacotherapeutic biomedical applications. Emphasis was placed on evaluating scientific resources related to recent advancements and future directions associated with its applications as delivery systems for drugs and biologics within the past decade thus complementing other specialized reviews showcasing the theme.

The Effects of Feed Frame Parameters and Turret Speed on Mini-Tablet Compression

Die filling is a critical process step during tablet production as it defines the tablet weight. Achieving die fill consistency during production of mini-tablets, tablets with diameters ≤6 mm, is considerably more challenging. Although die filling in rotary presses had been studied in relation to the feed paddle design, paddle speed, and turret speed, it is unclear how these process variables could impact mini-tablet production and product properties. In this study, 1.8 and 3 mm mini-tablets were prepared using a rotary press with multiple-tip tooling using different process configurations. Mini-tablet weight variation within and across compaction cycles were determined using data from compression roller displacement and mini-tablet weight. Higher die fill densities were achieved with a flat feed wheel paddle and high paddle speed. This was attributed to better granule fluidization in the feed frame, which also increased the intercycle weight variation and reduced tensile strength. The turret speed did not impact mini-tablet properties significantly. Granule overlubrication in the feed frame potentially reduced mini-tablet tensile strength during compaction. The number of paddle passes in the die fill region was correlated to mini-tablet die fill performance. Findings from this study could provide better insights into the relationship between process variables and mini-tablet product quality.

Effect of formulation and process variables on lipid based sustained release tablets via continuous twin screw granulation: A comparative study

The current study's aim is to prepare lipid based sustained release tablets via a twin-screw granulation technique and compare those dosage forms with conventional techniques, namely wet granulation and direct compression. The granules were successfully manufactured in a single-step, continuous twin-screw granulation process with a low proportion of binder (Klucel™ EF, HPC SSL) using Compritol® 888 ATO, Precirol® ATO 5 and Geleol™ as sustained release agents. The granules prepared showed good flow characteristics and compaction properties. DSC and XRD studies were conducted to characterize the granules prepared via a twin-screw granulation method and the results demonstrated the crystalline nature of lipids within the granules. FTIR data indicated that there were no interactions with the formulation components investigated. The formulations developed by all three methods were compressed into tablets with a mechanical strength of 14-16 KP. The tablets formulated were characterized for physicochemical properties, in vitro drug release studies, water uptake and erosion studies. These results showed that the drug was not completely released after 24 h for tablets developed by the wet granulation process using all three lipids. The tablets prepared by the direct compression method demonstrated a burst release within 8 to 10 h from Precirol ATO 5® and Geleol™ formulations compared to Compritol® 888 ATO. However, tablets prepared using twin-screw granulation exhibited sustained release of the drug over 24 h and the water uptake and erosion results were in accordance with dissolution data. Stability data for 45 days at accelerated conditions (40 °C/75% RH) showed similar release profiles with ƒ2 values above 50 for all of the twin screw granulation formulations, indicating the suitability of the process for formulating sustained release tablets. These findings of a single-step, continuous twin-screw granulation process are novel and demonstrate new opportunities for development of sustained release tablets.

GLUT1 -mediated venlafaxine-thiamine disulfide system-glucose conjugates with "lock-in" function for central nervous system delivery

Venlafaxine, a novel third-generation antidepressant drug, has been described as a reference treatment for major depression, owing to its ability of inhibiting both noradrenalin and serotonin neuronal reuptake, and inhibiting dopamine reuptake slightly. However, its clinical application is hampered by a limited brain distribution. Glucosylation is an effective way to enhance the brain targeting ability of drugs, but the bidirectional transport of glucose transporter 1 (GLUT₁ ) might decrease the concentrations of venlafaxine-glucose (V-G) in brain before the release of parent drug venlafaxine. To conquer this drawback of GLUT₁ , "lock-in" thiamine disulfide system (TDS) was introduced to modify the V-G conjugate. Both conjugates could release venlafaxine when incubated with the various buffers, mice plasma, and brain homogenate. The evaluation in vivo demonstrated that venlafaxine-TDS-glucose (V-TDS-G) had an improved targeting ability and significantly increased the level of venlafaxine in brain compared to the naked venlafaxine and V-G. The relative uptake efficiency (RE) and concentration efficiency (CE) were enhanced to 5.69 and 5.70 times higher than that of naked venlafaxine, respectively. The results of this study suggest that the conjugate strategy based on the glucose-TDS (G-TDS) is available to enhance the delivery of central nervous system (CNS) drugs into brain.

Evaluation of disintegrants functionality for orodispersible mini tablets

OBJECTIVE

This work evaluates the functionalities of different superdisintegrants (SD) for manufacturing orodispersible mini tablets (ODMT) by direct compression.

METHODS

Twenty-three formulations varying in SD type, concentration, and lubricant were used to manufacture ODMT. The ODMT were then characterized for the following properties: friability, porosity, tensile strength, in vivo and in vitro disintegration time (DT).

RESULTS

The results show that the presence, type, and concentration of SD did not influence friability, porosity, or tablet tensile strength. With regards to in vivo DT, only cross-linked poly (vinyl pyrrolidone) improved DT in all the tested formulations. Results also showed that when using microcrystalline cellulose (MCC) above 20% in the formulation, DT is longer. Cross-linked carboxymethyl cellulose accelerates DT when the MCC content is less than 20%. As for cross-linked carboxymethyl starch and calcium alginate showed no improvement on DT. Results for in vitro DT were all shorter than in vivo results and there was no correlation with the in vivo evaluation.

CONCLUSIONS

This study shows that there is a need to develop better in vitro testing that precisely simulates in vivo conditions and that are adapted to ODMT. This standardization of the test methods for ODMTs must be accompanied by an improvement in the comprehension of SD mechanisms.

Feasibility of mini-tablets as a flexible drug delivery tool

Mini-tablets have potential applications as a flexible drug delivery tool in addition to their generally perceived use as multi-particulates. That is, mini-tablets could provide flexibility in dose finding studies and/or allow for combination therapies in the clinic. Moreover, mini-tablets with well controlled quality attributes could be a prudent choice for administering solid dosage forms as a single unit or composite of multiple mini-tablets in patient populations with swallowing difficulties (e.g., pediatric and geriatric populations). This work demonstrated drug substance particle size and concentration ranges that achieve acceptable mini-tablet quality attributes for use as a single or composite dosage unit. Immediate release and orally disintegrating mini-tablet formulations with 30μm to 350μm (particle size d₉₀) acetaminophen and Compap™ L (90% acetaminophen) at concentrations equivalent to 6.7% and 26.7% acetaminophen were evaluated. Mini-tablets achieved acceptable weight variability, tensile strength, friability, and disintegration time at a reasonable solid fraction for each formulation. The content uniformity was acceptable for mini-tablets of 6.7% formulations with ≤170μm drug substance, mini-tablets of all 26.7% formulations, and composite dosage units containing five or more mini-tablets of any formulation. Results supported the manufacturing feasibility of quality mini-tablets, and their applicability as a flexible drug delivery tool.

Prolonged-release minitablets with carbamazepine – preliminary observations in vitro

Objective

The aim was to develop prolonged-release minitablets (MT) with carbamazepine (CBZ).

Methods

Matrix-type 3-mm MT (5 mg CBZ) were prepared by direct compression using hydrophilic (hypromellose) or hydrophobic polymers (ethylcellulose, Kollidon SR, glyceryl behenate). Coated prolonged-release MT (2.5 mm/3 mg of CBZ) were produced using ethylcellulose or Eudragit RL/RS. The release tests were performed in a basket apparatus with water or 1% sodium lauryl sulphate solution as dissolution media.

Key findings

High-viscosity hypromellose used as a matrix polymer resulted in slow release of CBZ (80% released during 12 h). Dissolution was slower from hydrophobic matrices. Non-swelling MT cores were successfully coated with Eudragit RL/RS, which resulted in the prolonged release of CBZ (80%/14 h), depending on the film thickness and Eudragit composition. Careful choice of pore formers in the coating film allowed to reduce lag time. Ethylcellulose was unsuitable as coating polymer due to low permeability to CBZ and unsatisfying mechanical resistance of the films modified with hypromellose.

Conclusion

Prolonged release of CBZ was obtained from both matrix-type and coated MT. Further development of MT as a single unit or multicompartment prolonged-release new dosage form especially suitable for children has been justified.