Transfer and scale-up of the manufacturing of orodispersible mini-tablets from a compaction simulator to an industrial rotary tablet press

The revival of the mini-tablets: Recent advancements, classifications and expectations for the future

Mini-tablets have recently raised huge interest in pharmaceutical industry. The present review aims to identify the rational, the opportunities and challenges of this emerging small solid drug dosage form by a structured literature review following the PRISMA algorithm. In total, more than 5,000 literature and patent sources have been found starting with the very first in the 60s of the past century, followed by the first multiparticular products using mini-tablets with pancreatin (Panzytrat® by the former BASF subsidiary Knoll/Nordmark) authorized in 1985. There seems to be a second boost of common interest in the 2000s when clinical studies demonstrated that one or more mini-tablets could enable superior drug administration even in very young patients including neonates over the former gold standard, a liquid drug preparation. Several pharmaceutical companies immediately started clinical development programs using the mini-tablet concept and the first products have been recently authorized by the competent authorities. Superiority was given as the mini-tablets ease the swallowing procedure compared to conventional tablets, enable various modified drug release opportunities including taste-masking by film-coating technology and provide excellent drug stability compared to liquid oral dosage forms. Due to these product attributes they are particularly beneficial to children and their caregivers. Furthermore, there is potential for precise individual drug dosing by counting adequate amounts of the multiple drug carriers. Most recently, two novel products with different concepts were authorized by the EMA and entered the market which are highlighted in this review: the first orodispersible mini-tablet with enalapril maleate for congenital heart failure (Aqumeldi® from Proveca Pharma) and the first single unit mini-tablet with matrix-type controlled melatonin release for insomnia (Slenyto® from Neurim Pharmaceuticals). Our review reveals, that the majority of the published scientific papers use co-processed, ready-to-use excipients for the orodispersible mini-tablet formulations. However, traditional fillers such as microcrystalline cellulose or lactose have also been used for immediate release mini-tablets after adding a (super)disintegrant and a lubricant. The manufacturing of mini-tablets is conducted on conventional rotary tablet presses, predominantly equipped with multi-tip toolings to improve the yield or production speed. Scaling-up has been successfully realized from compaction simulators to pilot and production scale. Film-coatings enabling gastric resistance, taste masking or sustained-release properties have been realized in both fluid-bed and drum coaters using the same polymers as for conventional tablets. There is still a significant lack in regulatory guidance despite the recent success of the mini-tablet concept, starting from suitable characterization methods in the pharmacopoeias up to the design and conduct of clinical studies on mini-tablets.

The impacts of roller compaction on the quality attributes of simultaneously compressed micro and minitablets

The challenges of developing good quality low dose minitablets was assessed by systematically studying the effects of ibuprofen (IBU, a model compound) particle sizes (6-58 µm D50) and concentrations (0.1-3 %w/w), roller compaction forces (3-7 kN/cm), and the minitablet sizes (1.2, 1.5 and 2 mm diameter). A novel compression approach, where all three minitablet sizes were simultaneously produced in a single compression run was used. Roller compacted ribbons, granules, minitablets were characterized for physico-mechanical properties and minitablets were also characterized for stratified content uniformity and weight uniformity. The results showed that roll force was the more dominant factor to ribbon solid fraction or tensile strength and granule size enlargement. Minitablets obtained from the granules had good weight uniformity; all but one batch met the criteria. The precise control of tooling lengths across the various sizes was found profoundly important for achieving expected weights, solid fraction, and tensile strength of the simultaneously produced minitablets. The roller compaction process considerably improved the CU variability of the minitablets as compared to the direct compression process. Smaller particle size and higher concentration of IBU, increased roller compaction force, and larger minitablet size improved the potency and content uniformity; however, only the minitablet size was a statistically significant factor in this study. As a product strategic design criterion, a threshold of 25 minitablets in a dosage unit would ensure robust downstream filling and weight verification operations as well as dose accuracy and uniformity (would pass stage 1 criteria). This study results demonstrated feasibility of the novel simultaneous compression approach and the roller compaction process in developing good quality minitablets.

Current State of Minitablet Product Design: A Review

Interest in minitablets (MTs) has grown exponentially over the last 20 years and especially the last decade, as evidenced by the number of publications cited in Scopus and PubMed. MTs offer significant opportunities for personalized medicine, dose titration and flexible dosing, taste masking, and customizing drug delivery systems. Advances in specialized MT tooling, manufacturing, and characterization instrumentation have overcome many of the earlier development issues. Breakthrough MT swallowability, acceptability, and palatability research have challenged the long-standing idea that only liquids are acceptable dosage forms for infants and young children. MTs have been shown to be a highly acceptable dosage form for infants, small children, and geriatric patients who have difficulty swallowing. This review discusses the current state of MT applications, acceptability in pediatric and geriatric populations, medication adherence, manufacturing processes such as tableting and coating, running powder and tablet characterization, packaging and MT dispensing, and regulatory considerations.

Challenges in the transfer and scale-up of mini-tableting: Case study with losartan potassium

Mini-tablets (MTs) with losartan potassium were developed to treat the rare disease Epidermolysis Bullosa. The focus was placed on transfer and scale-up of a direct compressible formulation from the compaction simulator STYL'One Evo (CS) to the rotary tablet press Korsch XM 12 (RP). Transfer of tabletability and compactibility profiles from CS to RP did not show good agreement, e.g. at a tableting pressure of 125 MPa mean tensile strengths (TS) of 4 MPa on CS and 1-1.5 MPa on RP were reached. These results highlight the impact of the feed frame on final product qualities depending on process and material factors. In the scale-up studies the critical quality attributes (CQAs) mass variation, content uniformity, TS and disintegration time were investigated. After an appropriate run-up time, most CQAs reached a plateau, after reaching a balance between influx, efflux and distribution of lubricant in the feed frame. TS values of 1-2 MPa, disintegration times of max. 50 s, mass variation of 0.9-2.2 % (CV) and acceptance values below 15.0 were reached depending on chosen process parameters.

Development of a simple in-die method for determination of capping tendency in rotary tableting machines

A rotary tableting machine is used for the continuous tableting process. Tableting conditions often result in capping, leading to serious problems during production. Several studies have been conducted to predict the tablet capping tendency. However, as most previous studies were conducted using a compaction simulator, there is a lack of technology that can be readily applied during actual production. Therefore, the present study aimed to develop a novel method for predicting tablet capping in a rotary tableting machine. We hypothesized that capping occurs when residual stress of the tablet inside a die exceeds the critical stress immediately before ejection. Residual stress was evaluated by measuring the in-line die-wall pressure in a rotary tableting machine. Additionally, critical stress was estimated from the tablet strength inside the die using the Rumpf's equation. The critical and residual stresses were compared to determine the capping tendency to some extent. The findings of this study will substantially contribute to the rapid detection of tablet capping during tablet production.

Texture analysis – a versatile tool for pharmaceutical evaluation of solid oral dosage forms

In the past few decades, texture analysis (TA) has gained importance as a valuable method for the characterization of solid oral dosage forms. As a result, an increasing number of scientific publications describe the textural methods that evaluate the extremely diverse category of solid pharmaceutical products. Within the current work, the use of texture analysis in the characterization of solid oral dosage forms is summarised with a focus on the evaluation of intermediate and finished oral pharmaceutical products. Several texture methods are reviewed regarding the applications in mechanical characterization, and mucoadhesion testing, but also in estimating the disintegration time and in vivo specific features of oral dosage forms. As there are no pharmacopoeial standards for pharmaceutical products tested through texture analysis, and there are important differences between reported results due to different experimental conditions, the choice of testing protocol and parameters is challenging. Thereby, this work aims to guide the research scientists and quality assurance professionals involved in different stages of drug development into the selection of optimal texture methodologies depending on the product characteristics and quality control needs.

Orally disintegrating drug carriers for paediatric pharmacotherapy

Non-compliance, dosing inaccuracy, choking risk, flavour, and instability, are some of the issues associated with paediatric, oral dosage forms - tablets, capsules, solutions, and suspensions. Orally disintegrating drug carriers, a dosage form with growing interest, are thought to overcome several of the challenges associated with these conventional formulations by rapidly disintegrating within the buccal cavity without the need for water. This review serves as an up-to-date report on the various types of orodispersible delivery systems, currently being developed or commercialized, by detailing their characteristics, manufacturing processes, and applications in the paediatric population. Mentioned are orodispersible tablets, films, wafers and lyophilisates, mini-tablets, capsules, granules, electrospun fibers and webs. Also highlighted are the choice of excipients, quality control requirements, and expected pharmacokinetics of orally disintegrating drug carriers concerning the paediatric population. Overall, orodispersible formulations, particularly tablets, films, and lyophilisates/wafers, have shown to be a valuable addition to medication administration in minors, thus the execution of more targeted research and development activities is expected to lead to enhanced paediatric care and outcomes.

Orally Dispersible Dosage Forms for Paediatric Use: Current Knowledge and Development of Nanostructure-Based Formulations

The paediatric population has always suffered from a lack of medicines tailored to their needs, especially in terms of accurate dosage, stability and acceptability. Orodispersible dosage forms have gone through a resurrection as an alternative to liquid formulations or fractioned solid formulations, although they are still subject to several inconveniences, among which the unpleasant taste and the low oral bioavailability of the API are the most significant hurdles in the way of achieving an optimal drug product. Nanostructures can address these inconveniences through their size and variety, owing to the plethora of materials that can be used in their manufacturing. Through the formation and functionalisation of nanostructures, followed by their inclusion in orodispersible dosage forms, safe, stable and acceptable medicines intended for paediatric use can be developed.