Justification of disintegration testing beyond current FDA criteria using in vitro and in silico models

In vitro and in silico methods to investigate the effect of moderately increasing medium viscosity and density on ibuprofen dissolution rate

Medium viscosity can affect drug dissolution rate, however, it is not usually considered in routine dissolution testing or less complex biorelevant media. The effects of moderately increasing medium viscosity on the in vitro and in silico dissolution of ibuprofen were investigated with two viscosity enhancing agents (VEA) (hydroxypropyl methylcellulose (HPMC) and sucrose), three viscosity levels (range 0.7-5.5 mPa.s), two solubilities and two fluid velocities in the paddle, flow-through and intrinsic dissolution apparatuses. A factorial design analysis highlighted which factors significantly affected key dissolution metrics. Experimental results in the flow-through apparatus (FTA) were compared with in silico dissolution profiles generated by an in-house simulation code (SIMDISSOTM). Increasing viscosity reduced the intrinsic dissolution rate of ibuprofen for both VEAs. The dissolution rate reduction was also observed in the FTA with sucrose, but less so with HPMC, suggesting particle wetting, motion and surface area effects. Particle motion simulations suggested reduced particle lifting times as viscosity increased, indicating an effect of viscosity on particle dispersal. The viscosity- and fluid density-mediated reduction in the dissolution rate observed with sucrose was accurately simulated by SIMDISSOTM, in particular at higher velocities. Velocity had a significant impact on dissolution rates in the paddle apparatus, with a significant viscosity-related reduction in dissolution observed in the low solubility-low velocity scenario. Even small increases in medium viscosity can reduce the dissolution rate of a BCS class II drug, and in silico particle motion and dissolution data can assist interpretation of particulate dissolution behaviour.

Development of a Swellable and Floating Gastroretentive Drug Delivery System (sfGRDDS) of Ciprofloxacin Hydrochloride

Sangelose^® (SGL) is a novel hydroxypropyl methylcellulose (HPMC) derivative that has been hydrophobically modified. Due to its high viscosity, SGL has the potential as a gel-forming and release-rate-controlled material for application in swellable and floating gastroretentive drug delivery systems (sfGRDDS). The aim of this study was to develop ciprofloxacin (CIP)-loaded sfGRDDS tablets comprised of SGL and HPMC in order to extend CIP exposure in the body and achieve optimal antibiotic treatment regimes. Results illustrated that SGL-HPMC-based sfGRDDS could swell to a diameter above 11 mm and showed a short floating lag time (<4 s) and long total floating time (>24 h) to prevent gastric emptying. In dissolution studies, CIP-loaded SGL-HPMC sfGRDDS demonstrated a specific biphasic release effect. Among the formulations, the SGL/type-K HPMC 15,000 cps (HPMC 15K) (50:50) group exhibited typical biphasic release profiles, with F4-CIP and F10-CIP individually releasing 72.36% and 64.14% CIP within 2 h dissolution, and sustaining release to 12 h. In pharmacokinetic studies, the SGL-HPMC-based sfGRDDS demonstrated higher C_max (1.56-1.73 fold) and shorter T_max (0.67 fold) than HPMC-based sfGRDDS. Furthermore, SGL 90L in GRDDS indicated an excellent biphasic release effect and a maximum elevation of relative bioavailability (3.87 fold). This study successfully combined SGL and HPMC to manufacture sfGRDDS that retain CIP in the stomach for an optimal duration while improving its pharmacokinetic characteristics. It was concluded that the SGL-HPMC-based sfGRDDS is a promising biphasic antibiotic delivery system that can both rapidly achieve the therapeutic antibiotic concentration and maintain the plasma antibiotic concentration for an extended period to maximize antibiotic exposure in the body.

Enhancement of the Solubility and Dissolution Rate of Telmisartan by Surface Solid Dispersions Employing Superdisintegrants, Hydrophilic Polymers and Combined Carriers

Telmisartan (Tel) is a potent antihypertensive drug with a very poor aqueous solubility, especially in pH ranging from 3 to 9 (i.e., biological fluids) that results in poor bioavailability. Our aim was to improve Tel solubility and dissolution rates without the need for expensive multistep procedures, and without inclusion of alkalinizers. This study adopted the use of surface solid dispersions (SSDs) employing superdisintegrants, hydrophilic polymers and combined carriers including a superdisintegrant with a hydrophilic polymer. Tel-SSDs were formulated using thesolvent evaporation method. Compatibility between Tel and different carriers was examined via FT-IR. Tel-SSDs were evaluated optically and thermally to reveal a complete loss of the crystalline nature of the drug. Both drug content and percentage yield were calculated to judge the efficiency of the preparation technique used. Saturation, aqueous solubility, and dissolutions rates were determined. Dissolution profiles were studied using model dependent and independent approaches and were subjected to the pair-wise procedure using the DDsolver software program. Effect of aging was studied by comparing the drug content and dissolution profiles of freshly prepared SSDs with aged samples. All Tel-SSDs showed acceptable physical properties. Tel-SSDs showed pertinent enhancement related to the carrier used. Combined surface solid dispersions employing superdisintegrant croscarmellose sodium with either hydrophilic polymer PEG 4000 or Poloxamer 407 gave remarkable enhancement in solubility and dissolution rates of Tel where more than 90% of the drug was released within 20 min. The effect of aging results proved a non-significant difference in the drug content and dissolution profiles between fresh and aged samples. Formulation of Tel SSDs using combined carriers proved to be effective in enhancing the aqueous solubility and dissolution rates of Tel, as well as showing good stability upon aging.

Intracranial In Situ Thermosensitive Hydrogel Delivery of Temozolomide Accomplished by PLGA–PEG–PLGA Triblock Copolymer Blending for GBM Treatment

Glioblastoma (GBM) recurrence after surgical excision has grown to be a formidable obstacle to conquer. In this research, biodegradable thermosensitive triblock copolymer, poly(D, L–lactic acid–co–glycolic acid)–b–poly(ethylene glycol)–b–poly(D, L–lactic acid–co–glycolic acid (PLGA–PEG–PLGA) was utilized as the drug delivery system, loading with micronized temozolomide(micro-TMZ) to form an in situ drug–gel depot inside the resection cavity. The rheology studies revealed the viscoelastic profile of hydrogel under various conditions. To examine the molecular characteristics that affect gelation temperature, ¹H–NMR, inverse gated decoupling ¹³C–NMR, and GPC were utilized. Cryo-SEM and XRD were intended to disclose the appearance of the hydrogel and the micro-TMZ existence state. We worked out how to blend polymers to modify the gelation point (T_gel) and fit the correlation between T_gel and other dependent variables using linear regression. To simulate hydrogel dissolution in cerebrospinal fluid, a membraneless dissolution approach was used. In vitro, micro-TMZ@PLGA–PEG–PLGA hydrogel exhibited Korsmeyer–Peppas and zero–order release kinetics in response to varying drug loading, and in vivo, it suppressed GBM recurrence at an astoundingly high rate. Micro-TMZ@PLGA–PEG–PLGA demonstrates a safer and more effective form of chemotherapy than intraperitoneal TMZ injection, resulting in a spectacular survival rate (40%, n = 10) that is much more than intraperitoneal TMZ injection (22%, n = 9). By proving the viability and efficacy of micro-TMZ@PLGA–PEG–PLGA hydrogel, our research established a novel chemotherapeutic strategy for treating GBM recurrence.

Modeling of In Vitro Dissolution Profiles of Carvedilol Immediate-Release Tablets in Different Dissolution Media

Quantitative evaluation of drug dissolution characteristics based on mathematical models is essential to understand and predict a particular drug release profile. In this study, model-dependent evaluation of the dissolution kinetics of reference and five test products (25-mg, immediate-release (IR) tablets) of an antihypertensive drug, carvedilol, was carried out using the DDSolver^® program. The effects of pH (pH 1.2, 4.5, and 6.8) and various media with/without 0.5% (w/v) anionic, cationic, and nonionic surfactants (sodium lauryl sulfate (SLS), hexadecyltrimethylammonium bromide (CTAB), and polysorbate 80) on the dissolution kinetics of the bioequivalent IR products of carvedilol were investigated. The Weibull-1 model was fitted successfully to the dissolution data of all products at pH 1.2 and pH 4.5, as well as in the pH 6.8 medium with CTAB according to the model goodness of fit (r² = 0.981-0.999, AIC = 14.5-42.6, MSC = 1.99-5.25). Model fitting produced good fits to Gompertz-1 for all products at pH 6.8 without a surfactant (r² = 0.975-0.998, AIC = 28.3-55, MSC = 2.53-5.82). For pH 6.8 media containing SLS or polysorbate 80, Logistic-2 was fitted successfully to the dissolution data of all products (r² = 0.974-0.999, AIC = 20.9-52.1, MSC = 1.90-5.69). Overall, the model-dependent analysis of in vitro dissolution data indicated in vitro equivalence of the reference and test products of carvedilol in each medium in terms of kinetic models, suggesting that it would have an important role in developing generic drug products of the BCS class II drug carvedilol.

Predictive selection rule of favourable image processing methods for X-ray micro-computed tomography images of tablets

Adequately processed X-ray micro-computed tomography images of real pharmaceutical formulations provide the possibility to validate in silico tools for the prediction of disintegration and/or dissolution. However, the evaluation of suitable image processing pathways is time consuming. The objective of this study was to prove the transferability of image processing methods and to develop an approach to select probable favourable image processing approaches for data sets with similar properties to accelerate the evaluation process. Therefore, data from a previously performed evaluation of image processing approaches and parameters were used to analyse the robustness of the image processing by statistical resampling and to develop a predictive rule set. The rule set was verified by both one new ratio of API and excipient within and outside of the ratios used to develop the rule. The rule was applied to images of a binary mixture with new compounds with similar determined image properties to prove the transferability of the rule set. It was possible to identify robust image processing pathways with narrow ranges of input parameters. The prediction of the image processing pathways led to high desirabilities which were confirmed by visual verification for ratios within the calibrated range. The transfer to the new binary mixture was successful and confirmed as well.

Mechanistic Models for USP2 Dissolution Apparatus, Including Fluid Hydrodynamics and Sedimentation

Drug product dissolution is a key input to Physiologically Based Biopharmaceutics Models (PBBM) to be able to predict in vivo dissolution. The integration of product dissolution in PBBMs for immediate release drug products should be mechanistic, i.e. allow to capture the main determinants of the in vitro dissolution experiment, and extract product batch specific parameter(s). This work focussed on the Product Particle Size Distribution (P-PSD), which was previously shown to integrate the effect of dose, volume, solubility (pH), size and concentration of micelles in the calculation of a batch specific input to PBBMs, and proposed new hydrodynamic (HD) models, which integrate the effect of USP2 apparatus paddle rotation speed and medium viscosity on dissolution. In addition, new models are also proposed to estimate the quantitative impact of formulation and drug sedimentation or "coning" on dissolution. Model "HDC-1" predicts coning in the presence of formulation insoluble excipients and "HDC-2" predicts the sedimentation of the drug substance only. These models were parameterized and validated on 166 dissolution experiments and 18 different drugs. The validation showed that the HD model average fold errors (AFE) for dissolution rate prediction of immediate release formulations, is comprised between 0.85 and 1.15, and the absolute average fold errors (AAFE) are comprised between 1.08 and 1.28, which shows satisfactory predictive power. For experiments where coning was suspected, the HDC-1 model improved the precision of the prediction (defined as ratio of "AAFE-1"values) by 2.46 fold compared to HD model. The calculation of a P-PSD integrating the impact of USP2 paddle rotation, medium viscosity and coning, will improve the PBBM predictions, since these parameters could have an influence on in vitro dissolution, and could open the way to better prediction of the effect of prandial state on human exposure, by developing new in silico tools which could integrate variation of velocity profiles due to the chyme viscosity.

A New Validation Methodology for In Silico Tools Based on X-ray Computed Tomography Images of Tablets and a Performance Analysis of One Tool

In silico tools which predict the dissolution of pharmaceutical dosage forms using virtual matrices can be validated with virtual matrices based on X-ray micro-computed tomography images of real pharmaceutical formulations. Final processed images of 3 different tablet batches were used to check the performance of the in silico tool F-CAD. The goal of this work was to prove the performance of the software by comparing the predicted dissolution profiles to the experimental ones and to check the feasibility and application of the validation concept for in silico tools. Both virtual matrices based on X-ray micro-computed tomography images and designed by the software itself were used. The resulting dissolution curves were compared regarding their similarity to the experimental curve. The kinetics were analysed with the Higuchi and Korsmeyers-Peppas plot. The whole validation concept as such was feasible and worked well. It was possible to identify prediction errors of the software F-CAD and issues with the virtual tablets designed within the software.

Evaluation of different segmentation methods of X-ray micro computed tomography images

In silico tools for the prediction of disintegration and/or dissolution of tablets can be validated using adequate images of real pharmaceutical formulations. X-ray micro-computed tomography images of 12 different tablet batches prepared from binary mixtures of API and excipient were used. The goal of this work was to compare different segmentation methods to improve the results and processing time of an evaluation of pre-processing methods. The open source software ImageJ was utilised for the image processing. Different threshold algorithms were applied as well as different cluster numbers for the k-means clustering. The pathways were analysed regarding their desirability which was calculated from the recovery rates and their ratios. It was possible to identify suitable pathways for each single batch as well as for combinations of several batches. The recovery rates of the best pathways were always approximately 100%. It was possible to confirm the correctness of the image processing by visual perception. The image processing could be improved and sped up.

Traditional Chinese Medicine "Pill", an Ancient Dosage Form with Surprising Modern Pharmaceutical Characteristics

Currently, the use of Traditional Chinese Medicine (TCM) for healthy living in daily practice is widely accepted across the world. However, not much attention has been paid to the particular characteristics of TCM "pills", one of the classic dosage forms in TCM. For a better understanding, this review was undertaken to provide a modern pharmaceutical overview of pills. Over many centuries, pills have been developed in different types (honeyed pill, water-honeyed pill, watered pill, pasted pill, waxed pill, concentrated pill, and dripping pill) to achieve varying intended TCM release patterns. It suggests that knowledge relating to the impact of binders and excipients on drug release from TCM pills can be traced back to before dissolution testing was invented. Therefore, although Pills may be considered as an ancient and outdated dosage form compared to current drug delivery systems, they have surprisingly modern pharmaceutical properties that is highlighted in this article. In addition, this review found that the quality control standards for TCM pill are globally substantially different. Hence, greater effort should be taken to establish an internationally harmonized and proper standard to safeguard the quality of this dosage form and to ensure the alignment with TCM use.

Best Practices in the Development and Validation of Physiologically Based Biopharmaceutics Modeling. A Workshop Summary Report

This workshop report summarizes the proceedings of Day 2 of a three-day workshop on "Current State and Future Expectations of Translational Modeling Strategies toSupportDrug Product Development, Manufacturing Changes and Controls". From a drug product quality perspective, physiologically based biopharmaceutics modeling (PBBM) is a tool to link variations in the drug product quality attributes to in vivo outcomes enabling the establishment of clinically relevant drug product specifications (CRDPS). Day 2 of the workshop focused on best practices in developing, verifying and validating PBBM. This manuscript gives an overview of podium presentations and summarizes breakout (BO) session discussions related to (1) challenges and opportunities for using PBBM to assess the clinical impact of formulation and manufacturing changes on the in vivo performance of a drug product, (2) best practices to account for parameter uncertainty and variability during model development, (3) best practices in the development, verification and validation of PBBM and (4) opportunities and knowledge gaps related to leveraging PBBM for virtual bioequivalence simulations.

Biphasic Dissolution as an Exploratory Method During Early Drug Product Development

Dissolution testing is a major tool used to assess a drug product's performance and as a quality control test for solid oral dosage forms. However, compendial equipment and methods may lack discriminatory power and the ability to simulate aspects of in vivo dissolution. Using low buffer capacity media combined with an absorptive phase (biphasic dissolution) increases the physiologic relevance of in vitro testing. The purpose of this study was to use non-compendial and compendial dissolution test conditions to evaluate the in vitro performance of different formulations. The United States Pharmacopeia (USP)-recommended dissolution method greatly lacked discriminatory power, whereas low buffer capacity media discriminated between manufacturing methods. The use of an absorptive phase in the biphasic dissolution test assisted in controlling the medium pH due to the drug removal from the aqueous medium. Hence, the applied non-compendial methods were more discriminative to drug formulation differences and manufacturing methods than conventional dissolution conditions. In this study, it was demonstrated how biphasic dissolution and a low buffer capacity can be used to assess in vitro drug product performance differences. This can be a valuable approach during the early stages of drug product development for investigating in vitro drug release with improved physiological relevance.

In silico Tools at Early Stage of Pharmaceutical Development: Data Needs and Software Capabilities

In early drug development, the selection of a formulation platform and decisions on formulation strategies have to be made within a short timeframe and often with minimal use of the active pharmaceutical ingredient (API). The current work evaluated the various physicochemical parameters required to improve the prediction accuracy of simulation software for immediate release tablets in early drug development. DDDPlus™ was used in simulating dissolution test profiles of immediate release tablets of ritonavir and all simulations were compared with experimental results. The minimum data requirements to make useful predictions were assessed using the ADMET predictor (part of DDDPlus) and Chemicalize (an online resource). A surfactant model was developed to estimate the solubility enhancement in media containing surfactant and the software's transfer model based on the USP two-tiered dissolution test was assessed. One measured data point was shown to be sufficient to make predictive simulations in DDDPlus. At pH 2.0, the software overestimated drug release while at pH 1.0 and 6.8, simulations were close to the measured values. A surfactant solubility model established with measured data gave good dissolution predictions. The transfer model uses a single-vessel model and was unable to predict the two in vivo environments separately. For weak bases like ritonavir, a minimum of three solubility data points is recommended for in silico predictions in buffered media. A surfactant solubility model is useful when predicting dissolution behavior in surfactant media and in silico predictions need measured solubility data to be predictive.

A multivariate investigation into the relationship between pharmaceutical characteristics and patient preferences of bioequivalent ibuprofen tablets

BACKGROUND

In Spain the price of all ibuprofen 600 mg tablet generic products is the same due to reimbursement existing rules so for the patient there is not any economic incentive to choose a particular one. Bearing in mind that the quality of generic products should be similar, it could be questioned if differences in patient preferences evaluated as sales could be related to differences on their pharmaceutical properties. The aims of this work were to study the variability on the pharmaceutical characteristics of marketed bioequivalent tablet formulations and its impact on patient preferences.

METHODS

Thirty-six batches corresponding to fourteen different generic products were chosen among the best-selling products of the Spanish market in the years 2011 and 2015 and were compared to the reference product. The effect on patient preferences of six variables was studied through a multivariate analysis. The first two variables were marketing characteristics: 1) years in the market and 2) the number of other generic products marketed by the same manufacturer, which could be related to the size and service provided by the manufacturer. The other four variables studied were pharmaceutical tablet properties: 3) mean weight, 4) hardness, 5) disintegration, and 6) dissolution. A multiple linear regression analysis was performed to identify the effect on sales of the six variables studied.

RESULTS

The disintegration time was the most significant (P=0.018) factor affecting the sales of Ibuprofen tablets which may be related to the onset of action.

CONCLUSION

The faster the tablet disintegration, the higher its sales. Two possible explanations are suggested: 1) the most specialized ibuprofen tablet manufacturer considers fast disintegration as a key parameter and/or 2) habitual consumers of ibuprofen can detect small differences on the onset of action among different marketed formulations. In this work, all marketed ibuprofen tablets comply with the pharmacopoeia specifications.