Probing the early stages of tablet disintegration by stress relaxation measurement

Impact of immediate release film coating on the disintegration process of tablets

Pharmaceutical tablets are often coated with a layer of polymeric material to protect the drug from environmental degradation, facilitate the packaging process, and enhance patient compliance. However, the detailed effects of such coating layers on drug release are not well understood. To investigate this, flat-faced pure microcrystalline cellulose tablets with a diameter of 13 mm and a thickness between 1.5 mm to 1.6 mm were directly compressed, and a film coating layer with a thickness of 80 μm to 120 μm was applied to one face of these tablets. This tablet geometry and immediate release film coating were chosen as a model system to understand how the film coating interacts with the tablet core. The coating hydration and dissolution process was studied using terahertz pulsed imaging, while optical coherence tomography was used to capture further details on the swelling process of the polymer in the coated tablet. The study investigated the film coating polymer dissolution process and found the gelling of dissolving polymer restricted the capillary liquid transport in the core. These findings can help predict the dissolution of film coating within the typical range of thickness (30 μm to 40 μm) and potentially be extended to understand modified release coating formulations.

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.

Tablet disintegration performance: Effect of compression pressure and storage conditions on surface liquid absorption and swelling kinetics

The disintegration process of pharmaceutical tablets is a crucial step in the oral delivery of a drug. Tablet disintegration does not only refer to the break up of the interparticle bonds, but also relates to the liquid absorption and swelling behaviour of the tablet. This study demonstrates the use of the sessile drop method coupled with image processing and models to analyse the surface liquid absorption and swelling kinetics of four filler combinations (microcrystalline cellulose (MCC)/mannitol, MCC/lactose, MCC/dibasic calcium phosphate anhydrous (DCPA) and DCPA/lactose) with croscarmellose sodium as a disintegrant. Changes in the disintegration performance of these formulations were analysed by quantifying the effect of compression pressure and storage condition on characteristic liquid absorption and swelling parameters. The results indicate that the disintegration performance of the MCC/mannitol and MCC/lactose formulations are driven by the liquid absorption behaviour. For the MCC/DCPA formulation, both liquid absorption and swelling characteristics affect the disintegration time, whereas DCPA/lactose tablets is primarily controlled by swelling characteristics of the various excipients. The approach discussed in this study enables a rapid (<1 min) assessment of characteristic properties that are related to tablet disintegration to inform the design of the formulation, process settings and storage conditions.

Exploring the performance-controlling tablet disintegration mechanisms for direct compression formulations

The design and manufacture of tablets is a challenging process due to the complex interrelationships between raw material properties, the manufacturing settings and the tablet properties. An important factor in formulation and process design is the fact that raw material and tablet properties drive the disintegration and dissolution performance of the final drug product. This study aimed to identify the mechanisms which control tablet disintegration for 16 different immediate-release placebo formulations based on raw material and tablet properties. Each formulation consisted of two fillers (47% each), one disintegrant and a lubricant. Tablets were manufactured by direct compression using four different combinations of the fillers microcrystalline cellulose (MCC), mannitol, lactose and dibasic calcium phosphate anhydrous (DCPA). The disintegration mechanism was primarily driven by the filler combination, where MCC/lactose tablets were identified as wettability controlled, MCC/mannitol tablets as dissolution controlled and DCPA-based tablets (MCC/DCPA and lactose/DCPA) as swelling controlled. A change of 2% in porosity for the wettability controlled tablets (MCC/lactose) caused a significant acceleration of the disintegration process (77% reduction of disintegration time), whereas for swelling controlled tablets (MCC/DCPA) the same porosity change did not considerably impact the disintegration process (3% change in disintegration time). By classifying these formulations, critical formulation and manufacturing properties can be identified to allow tablet performance to be optimised.

Disintegrant Selection in Hydrophobic Tablet Formulations

The hydrophobicity of poorly soluble drugs can delay tablets disintegration. We probed here the influence of different disintegrants on the disintegration of challenging hydrophobic formulations. Tablets containing diluents, hydrogenated vegetable oil and either sodium starch glycolate (SSG), croscarmellose sodium (CCS) or crospovidone (XPVP) were prepared. The disintegration time of tablets was tested immediately and after storage at 40 °C and 75% RH in sealed bags. Results show that storage and compression force had a negative effect on disintegration, particularly with 1% disintegrant. The performance of the three disintegrants was in the following order: CCS (best) > SSG > XPVP. For example, tablets containing 1% CCS, SSG and XPVP, compressed at 20 kN, disintegrated in ≈3, ≈12 and ≈69 min, respectively, after two months storage. Settling volume, liquid uptake and effect of storage on physical properties of the pure disintegrants were also studied and revealed that the reduced performance of XPVP is related to: 1) its rapid, yet short-range expansion upon liquid exposure and 2) its change of behaviour on storage. In conclusion, CCS ensured rapid disintegration at low concentration across various compression forces and storage times. Thus, the use of CCS in hydrophobic tablet formulations is recommended.

The influence of ethanol on superdisintegrants and on tablets disintegration

Disintegration of immediate release tablets originates from the volume expansion of disintegrants within the formulation. Here, we study the impact of ethanol on the disintegrant expansion and on tablets disintegration. The three most commonly used superdisintegrants, namely sodium starch glycolate (SSG), crospovidone (PVPP) and croscarmellose sodium (CCS) were investigated alone and incorporated in dicalcium phosphate and in drug-containing tablets. High (i.e. 40%), but not moderate (i.e. 10%), aqueous ethanol concentrations reduce the size expansion of the three disintegrants compared to water. This "ethanol effect" is the greatest for SSG, followed by CCS and then PVPP. Moreover, the presence of ethanol in the media can significantly influence the disintegration time of drug-containing tablets via affecting both the disintegrant action itself and the drug solubility. For example, the disintegration time of theophylline tablets containing SSG is 8.1-fold greater in 40% aqueous ethanol compared to water. Overall, this study brought to light the existence of a potentially significant interference of alcohol with the disintegration phenomenon, suggesting that the concomitant administration of tablets and intake of alcoholic beverages may affect, in some cases, tablets disintegration. More studies are now needed to verify the importance of the "ethanol effect" on disintegration of commercial dosage forms. Our findings also suggest that PVPP is the disintegrant that is the least affected by alcohol.