Physical mechanical and tablet formation properties of hydroxypropylcellulose: in pure form and in mixtures

Effect of hydroxy propyl cellulose grade and foam quality on foam granulation of a high drug load formulation

Foam granulation is a relatively newer wet granulation process whereby foamed binder solutions are added to the powders in the mixer to reduce localized over-wetting encountered during the wet granulation. This study is the first to investigate the effect of binder grade and foam quality on foam granulation process and granule properties of a high drug load formulation. Two different HPC grades, HPC LF (two times more viscous) and HPC EXF at an equivalent 7.4%w/w solution concentration, and foam quality of 50%, 90% and binder solution dripped were added to a high drug load (81%w/w) formulation for wet granulation. The granules were evaluated for compactibility and resultant compact strengths. The 50% foam quality of either HPC LF and HPC EXF resulted in lowest impeller power reading and water activity compared to 90% foam quality or dripped HPC solution. Granules prepared with 50% foam quality also exhibited smaller granule size, wider size distribution and higher specific surface area, resulting in higher compactibility. Whilst the granules prepared with different foamed HPC grades were not significantly different in compression behavior, they were higher in compact strengths, suggesting that foam mixing was more efficient in binder distribution compared to binder liquid penetration and distribution.

Advances in the development of amorphous solid dispersions: The role of polymeric carriers

Amorphous solid dispersion (ASD) is one of the most effective approaches for delivering poorly soluble drugs. In ASDs, polymeric materials serve as the carriers in which the drugs are dispersed at the molecular level. To prepare the solid dispersions, there are many polymers with various physicochemical and thermochemical characteristics available for use in ASD formulations. Polymer selection is of great importance because it influences the stability, solubility and dissolution rates, manufacturing process, and bioavailability of the ASD. This review article provides a comprehensive overview of ASDs from the perspectives of physicochemical characteristics of polymers, formulation designs and preparation methods. Furthermore, considerations of safety and regulatory requirements along with the studies recommended for characterizing and evaluating polymeric carriers are briefly discussed.

Variability in the substitution pattern of hydroxypropyl cellulose affects its physico-chemical properties

Hydroxypropyl cellulose (HPC) is a water-soluble polymer with many applications in food, pharmaceutical, medical, or paints industries. Past studies have reported that differences in functionality can occur between products of similar pharmaceutical grades. Understanding the origin of these differences is a major challenge for the industry. In this work, the structure and physico-chemical properties of several HPC samples of the same commercial grade were studied. Structural analysis by NMR and enzymatic hydrolysis were performed to study molar substitution and distribution of substituents along the polymer chain respectively. Water-polymer interactions, surface properties as well as rheological and thermal behavior were characterized to tentatively correlate them with the structure, and gain new insights into the structure-function relationship of this polymer. The differences in structure revealed between the samples affect their properties. The unexpected behavior of one sample was attributed to a more heterogeneous substitution pattern, with the coexistence of highly and weakly substituted regions along the same polymer chain. The more block-like distribution of substituents has a great effect on the clouding behavior and surface tension reduction ability of the polymer.

Formulation development and in Vitro-Ex vivo characterization of hot-melt extruded ciprofloxacin hydrochloride inserts for ocular applications: Part I

This study developed, optimized, characterized, and evaluated bioadhesive, hot-melt extruded (HME), extended-release ocular inserts containing ciprofloxacin hydrochloride (CIP-HCL) to improve the therapeutic outcomes of ocular bacterial infections. The inserts were fabricated with FDA-approved biocompatible, biodegradable, and bioadhesive polymers that were tuned in different ratios to achieve a sustained release profile. The results revealed an inverse relationship between the Klucel™ hydroxypropyl cellulose (HPC, 140,000 Da) concentration and drug release and extended-release profile over 24 h. The CIP-HCL-HME inserts presented stable drug content, thermal behavior, surface pH, and release profiles over three months of room-temperature storage and demonstrated adequate mucoadhesive strength. SEM micrographs revealed a smooth surface. Bacterial growth was not observed on the samples during the in vitro release experiment (0.5-24 h), indicating that a minimum inhibitory concentration (MIC) of 90 against Pseudomonas aeruginosa was achieved. Ex vivo transcorneal permeation studies using excised rabbit corneas revealed that the prepared ocular inserts prolonged the transcorneal flux of the drug compared to commercial eye drops and immediate-release inserts and could reduce the administration frequency to once daily. Therefore, the inserts could increase patient compliance and exhibited prolonged antibacterial activity and thus could provide better therapeutic outcomes against ocular bacterial infections.

The influence of input material properties on hot melt granules prepared using a counter-rotating batch mixer

OBJECTIVE

The objective of this study was to develop a method that enabled granulation in a counter-rotating batch mixer to emulate large scale dry twin screw granulation trials.

METHODS

Four granulations were prepared using counter rotating batch mixing for formulations containing a mixture of different particle sizes of the API (70% w/w) and polymer (30% w/w). Milled theophylline (MTHF; fine API) was blended with coarse hydroxypropyl cellulose (HPC MF; coarse polymer), theophylline (THF; coarse API) with fine hydroxypropyl cellulose (HPC EXF, fine polymer), and the other two formulations consisted of both components in the blend being fine or coarse.

RESULTS

The formulations selected for granulation had the lowest friction coefficient, f, as a function of drug load determined by the iShear^® powder flow rheometer. Despite the non-uniform chaotic and random nature of thermal granulation, each formulation granulated reproducibly, though the evolution for each was different.

CONCLUSION

This work highlighted that, firstly it is possible to measure plastic and frictional energy dissipation as product temperature. Secondly, granule growth and density were found to be proportional to the onset of polymer molecular mobility activated by the heat liberated from interparticle velocity differences via mechanical work (torque) required to move agglomerates through the mixer for the duration of each run.

Moisture Sorption by Polymeric Excipients Commonly Used in Amorphous Solid Dispersions and its Effect on Glass Transition Temperature: II. Cellulosic Polymers

Moisture sorption by polymeric carriers used for the development of amorphous solid dispersions (ASDs) plays a critical role in the physical stability of dispersed drugs since moisture may decrease glass transition temperature (T_g) and thereby increase molecular mobility of drugs leading to their crystallization. To assist the selection of appropriate polymers for ASDs, we conducted moisture sorption by five types of cellulosic polymers, namely, hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC), hydroxypropyl methyl cellulose acetate succinate (HPMCAS), hydroxypropyl methyl cellulose phthalate (HPMCP), and ethyl cellulose (EC), as functions of relative humidity (10 to 90% RH) and temperature (25 and 40 °C). The moisture sorption was in the order of HPC>HPMC>HPMCP>HPMCAS>EC, and there was no significant effect of the molecular weights of polymers on moisture uptake. There was also less moisture sorption at 40 °C than that at 25 °C. Glass transition temperatures (T_g) of the polymers decreased with the increase in moisture content. However, the plasticizing effect by moisture on HPC could not be determined fully since, despite being amorphous, there were very little baseline shifts in DSC scans. There was also very shallow baseline shift for HPMC at >1% moisture content. In contrast, T_g of HPMCAS and HPMCP decreased in general agreement with the Gordon-Taylor/Kelley-Bueche equation, and EC was semicrystalline having both T_g and melting endotherm, with only minor effect of moisture on T_g. The results of the present investigation would lead to a systematic selection of polymeric carriers for ASDs.

Evaluation of Hydroxyethyl Cellulose Grades as the Main Matrix Former to Produce 3D-Printed Controlled-Release Dosage Forms

Diclofenac sodium tablets were successfully prepared via hot-melt extrusion (HME) and fused deposition modeling (FDM), using different molecular-weight (Mw) grades of hydroxyethyl cellulose (HEC) as the main excipient. Hydroxypropyl cellulose (HPC) was added to facilitate HME and to produce drug-loaded, uniform filaments. The effect of the HEC grades (90–1000 kDa) on the processability of HME and FDM was assessed. Mechanical properties of the filaments were evaluated using the three-point bend (3PB) test. Breaking stress and distance were set in relation to the filament feedability to identify printer-specific thresholds that enable proper feeding. The study demonstrated that despite the HEC grade used, all formulations were at least printable. However, only the HEC L formulation was feedable, showing the highest breaking stress (29.40 ± 1.52 MPa) and distance (1.54 ± 0.08 mm). Tablet drug release showed that the release was Mw dependent up to a certain HEC Mw limit (720 kDa). Overall, the release was driven by anomalous transport due to drug diffusion and polymer erosion. The results indicate that despite being underused in FDM, HEC is a suitable main excipient for 3D-printed dosage forms. More research on underutilized polymers in FDM should be encouraged to increase the limited availability.

Water-Responsive Self-Repairing Superomniphobic Surfaces via Regeneration of Hierarchical Topography

Superomniphobic surfaces that can self-repair physical damage are desirable for sustainable performance over time in many practical applications that include self-cleaning, corrosion resistance, and protective gears. However, fabricating such self-repairing superomniphobic surfaces has thus far been a challenge because it necessitates the regeneration of both low-surface-energy materials and hierarchical topography. Herein, a water-responsive self-repairing superomniphobic film is reported by utilizing cross-linked hydroxypropyl cellulose (HPC) composited with silica (SiO₂) nanoparticles (HPC-SiO₂) that is treated with a low-surface-energy perfluorosilane. The film can repair physical damage (e.g., a scratch) in approximately 10 s by regenerating its hierarchical topography and low-surface-energy material upon the application of water vapor. The repaired region shows an almost complete recovery of its inherent superomniphobic wettability and mechanical hardness. The repairing process is driven by the reversible hydrogen bond between the hydroxyl (-OH) groups which can be dissociated upon exposure to water vapor. This results in a viscous flow of the HPC-SiO₂ film into the damaged region. A mathematical model composed of viscosity and surface tension of the HPC-SiO₂ film can describe the experimentally measured viscous flow with reasonable accuracy. Finally, we demonstrate that the superomniphobic HPC-SiO₂ film can repair physical damage by a water droplet pinned on a damaged area or by sequential rolling water droplets.

Understanding Direct Powder Extrusion for Fabrication of 3D Printed Personalised Medicines: A Case Study for Nifedipine Minitablets

Fuse deposition modelling (FDM) has emerged as a novel technology for manufacturing 3D printed medicines. However, it is a two-step process requiring the fabrication of filaments using a hot melt extruder with suitable properties prior to printing taking place, which can be a rate-limiting step in its application into clinical practice. Direct powder extrusion can overcome the difficulties encountered with fabrication of pharmaceutical-quality filaments for FDM, allowing the manufacturing, in a single step, of 3D printed solid dosage forms. In this study, we demonstrate the manufacturing of small-weight (<100 mg) solid dosage forms with high drug loading (25%) that can be easily undertaken by healthcare professionals to treat hypertension. 3D printed nifedipine minitablets containing 20 mg were manufactured by direct powder extrusion combining 15% polyethylene glycol 4000 Da, 40% hydroxypropyl cellulose, 19% hydroxy propyl methyl cellulose acetate succinate, and 1% magnesium stearate. The fabricated 3D printed minitablets of small overall weight did not disintegrate during dissolution and allowed for controlled drug release over 24 h, based on erosion. This release profile of the printed minitablets is more suitable for hypertensive patients than immediate-release tablets that can lead to a marked burst effect, triggering hypotension. The small size of the minitablet allows it to fit inside of a 0-size capsule and be combined with other minitablets, of other API, for the treatment of complex diseases requiring polypharmacy within a single dosage form.

Co-Spray Drying of Paracetamol and Propyphenazone with Polymeric Binders for Enabling Compaction and Stability Improvement in a Combination Tablet

Paracetamol (PCT) and propyphenazone (PRP) are analgesic drugs that are often combined in a single dosage form for enhanced pharmacological action. In this work, PCT and PRP were co-spray dried separately with hydroxypropyl methylcellulose (HPMC) and hydroxypropyl cellulose (HPC) using drug suspensions in polymer solutions as feed liquids. It was thought that because of polymer adherence to the surface of drug particles, the risk of PCT–PRP contact and interaction could be reduced. Such interaction may be caused by localized temperature gradients due to frictional forces during tableting, or during storage under harsh conditions. A worst-case scenario would be eutectic formation due to variations in powder mixture homogeneity since eutectic and therapeutic mass PCT/PRP ratios are close (65:35 and 60:40, respectively) and eutectic temperature is low (~56 °C). Uniform particle size, round shape, compaction improvement and faster release of the analgesics were important additional benefits of co-spray drying. Experimental design was first applied for each drug to optimize the polymer concentration on the yield of spray drying and melting point separation (Δmp) of heated binary mixtures of co-spray dried PCT/neat PRP, and vice versa, with the two drugs always included at their therapeutic 60:40 ratio. Optimal combinations with largest Δmp and production yield were: co-spray dried PCT (15% HPC) with neat PRP and co-spray dried PRP (10% HPMC) with neat PCT. Compression studies of these combinations showed tableting improvement due to the polymers, as reflected in greater work of compaction and solid fraction, greater fracture toughness and tablet strength, easier tablet detachment from the punch surface and ejectability. Faster release of both drugs was obtained from the tablet of co-spray dried PCT (15% HPC) with neat PRP. A one-month stability test (75% RH/40 °C) showed moisture-induced alteration tablet strength.

Effect of binder type and lubrication method on the binder efficacy for direct compression

The effect of different binders for direct compression on tablet critical quality attributes was investigated. Dicalcium phosphate, lactose and microcrystalline cellulose were used as fillers and combined with ten binders (10, 20 and 30% w/w). Binder properties were linked to tensile strength via partial least square analysis. Tablets containing VA64F and PH105 exhibited the highest tensile strength which was linked to their compaction properties (specific work of compaction, elasticity, cohesion index) and particle size. In contrast, S1500 and E15 exhibited the lowest tensile strength of all binders. Lubrication method influenced the tensile strength as lubricant sensitivity was observed to some extent for all binders. Tensile strength was significantly higher applying external compared to internal lubrication. Fast disintegration was observed for MCC (PH105 and PH200) and starch (S1500 and NMSt) grades, whereas HPC (KEXF and KEF) and E15 resulted in delayed disintegration. Wettability measurements, via determination of contact angle, correlated well with the disintegration behaviour of the binders and can therefore be used as an indicative measurement for tablet disintegration. This study revealed the effect of binder properties, filler type and lubrication method on tablet critical quality attributes. In addition, the potential of dry binder addition for direct compression was highlighted.

Polymeric drug delivery systems by additive manufacturing

Additive manufacturing (AM) is gaining interests in drug delivery applications, offering innovative opportunities for the design and development of systems with complex geometry and programmed controlled release profile. In addition, polymer-based drug delivery systems can improve drug safety, efficacy, patient compliance, and are the key materials in AM. Therefore, combining AM and polymers can be beneficial to overcome the existing limitations in the development of controlled release drug delivery systems. Considering these advantages, here we are focusing on the recent developments in the field of polymeric drug delivery systems prepared by AM. This review provides a comprehensive overview on a holistic polymer-AM perspective for drug delivery systems with discussion on the materials, properties, design and fabrication techniques and the mechanisms used to achieve a controlled release system. The current challenges and future perspectives for personalized medicine and clinical use of these systems are also briefly discussed.

Formulation, in vitro characterization and optimization of taste-masked orally disintegrating co-trimoxazole tablet by direct compression

Introduction

Orally disintegrating tablet (ODT) is a dosage form that overcomes the problem of swallowing which is prevalent in about 35% of the general population. Co-trimoxazole (CTX) is given for patients with HIV for the prophylaxis of opportunistic infection (OI), commonly for pneumocystis carinii pneumonia. It was reported that CTX was associated with a 25–46% reduction in mortality among individuals infected with HIV in sub-Saharan Africa. Esophageal candidiasis which usually comes along with HIV/AIDS is one of AIDS defining illness affecting up to 1 in 5 of people with AIDS. This opportunistic illness is manifested by painful or difficulty of swallowing. In this respect, CTX ODT offer the advantages of both liquid dosage forms in terms of easy swallowing thereby improve patient compliance and solid dosage forms in terms of dose uniformity, stability, lower production, and transportation costs. The objective of this study was to formulate, characterize and optimize CTX ODT which could overcome swallowing problem and improve patient compliance. Co-trimoxazole ODTs were prepared by direct compression technique using a semi synthetic super disintegrant (crospovidone) along with other excipients. Two taste masking techniques were employed, addition of sweetening agent, and solid dispersion by using a pH sensitive polymer, Eudragit E-100 at different ratios (1:1, 1:2 and 1:3). Taste masking was determined by comparing taste threshold value and in vitro drug release. Preliminary study was used to investigate the effect of crospovidone, compression force (CF) and Hydroxypropyl cellulose (HPC) on disintegration time, friability and wetting time (WT). Factorial design was used as it enables simultaneous evaluation of formulation variables and their interaction effect. From the preliminary study, the factors that were found significant were further optimized using central composite design. Design-Expert 8.0.7.1 software was employed to carry out the experimental design. The bitterness threshold concentration of Trimethoprim was found to be 150 μg/ml and the in vitro drug release of the three batches of drug to polymer ratio (F1:1, 1:2 and 1:3) was 2.80±0.05, 2.77±0.00 and 2.63±0.00 respectively. From the optimization study, the optimal concentration for the superdisintegrant was 8.60% w/w and a CF of 11.25 KN which gave a rapid disintegration and WT of 13.79 and 23.19 seconds respectively and a friability of 0.666%.

Conclusion

In this study, co-trimoxazole ODT was formulated successfully. Central composite design was effectively used to model and optimize friability, DT and WT. The method was found effective for estimating the effect of independent variables on the dependent variables by using polynomial equation and surface plots. Optimization of the response variables was possible by using both numerical and graphical optimization and the predicted optimal conditions were confirmed experimentally and were found to be in good agreement within 5% of the predicted responses. The results of the study showed that CTX ODT had significantly rapid disintegration, less than 1% friability and enhanced dissolution profiles. The successful formulation of CTX ODT can solve difficulty of swallowing of conventional tablets for some group of patients which are unable to swallow solid oral dosage form.

Co-processing of small molecule excipients with polymers to improve functionality

INTRODUCTION

Polymers have various applications such as binder, film coating agent, stabilizer, drug release modification, and as primary packaging materials. Recently, they have been explored in co-processing technique to improve the functionality of small molecule excipients (SMEs). Co-processing is a concept wherein two or more excipients interact at sub-particle level to provide synergy in functionality and minimize drawbacks of individual excipients.

AREA COVERED

The present review highlights the application of co-processing to improve the functionality of SMEs using polymers; physicochemical and mechanical properties of polymers for co-processing; advantages of co-processed excipients for different applications; functionality enhancement of co-processed excipients; novel concepts/methods for co-processing; mechanistic insights on co-processing and commercial products available in the market.

EXPERT OPINION

Most of the SMEs do not possess optimal multifunctional properties like flow, compressibility, compactibility, and disintegration ability, required to compensate for poorly compactable drugs. Some of these drawbacks can be overcome by co-processing of SMEs with polymers. For example, co-processing of a brittle SME and plastic material (polymer) can provide a synergistic effect and result in the generation of single entity multi-functional excipient. Besides, novel co-processed excipients generated using combinations of SMEs and polymers can also generate intellectual property rights.

Phase behavior of ASDs based on hydroxypropyl cellulose

Novel polymeric carriers for amorphous solid dispersions (ASDs) are highly demanded in pharmaceutical industry to improve the bioavailability of poorly-soluble drug candidates. Besides established polymer candidates, hydroxypropyl celluloses (HPC) comes more and more into the focus of ASD production since they have the availability to stabilize drug molecules in aqueous media against crystallization. The thermodynamic long-term stability of HPC ASDs with itraconazole and fenofibrate was predicted in this work with PC-SAFT and compared to three-months enduring long-term stability studies. The glass-transition temperature is a crucial attribute of a polymer, but in case of HPC hardly detectable by differential scanning calorimetry. By investigating the glass transition of HPC blends with a miscible polymer, we were for the first time able to estimate the HPC glass transition. Although both, fenofibrate and itraconazole reveal a very low crystalline solubility in HPC regardless of the HPC molecular weight, we observed that low-molecular weight HPC grades such as HPC-UL prevent fenofibrate crystallization for a longer period than the higher molecular weight HPC grades. As predicted, the ASDs with higher drug load underwent amorphous phase separation according to the differential scanning calorimetry thermograms. This work thus showed that it is possible to predict critical drug loads above which amorphous phase separation and/or crystallization occurs in HPC ASDs.

Effect of Hydroxypropyl Cellulose Level on Twin-Screw Melt Granulation of Acetaminophen

This study investigated the effect of binder level on the physicochemical changes and tabletability of acetaminophen (APAP)-hydroxypropyl cellulose (HPC) granulated using twin-screw melt granulation. Even at 5% HPC level, the tablet tensile strength achieved up to 3.5 MPa. A minimum of 10% HPC was required for the process robustness. However, 20% HPC led to tabletability loss, attributable to the high mechanical strength of APAP granules. The over-granulated APAP granules had thick connected HPC scaffold and low porosity. Consequently, these granules were so strong that they underwent a lower degree of fracture under compression and higher elastic recovery during decompression. HPC was enriched on the surface of APAP extrudates at all HPC levels. Amorphous APAP was also observed on the extrudate surface at 20% HPC level, and it recrystallized within 24 h storage. To achieve a robust process and optimal improvement in APAP tabletability, the preferred HPC level was 10 to 15%.

Polymer Selection for Hot-Melt Extrusion Coupled to Fused Deposition Modelling in Pharmaceutics

Three-dimensional (3D) printing offers the greatest potential to revolutionize the future of pharmaceutical manufacturing by overcoming challenges of conventional pharmaceutical operations and focusing design and production of dosage forms on the patient’s needs. Of the many technologies available, fusion deposition modelling (FDM) is considered of the lowest cost and higher reproducibility and accessibility, offering clear advantages in drug delivery. FDM requires in-house production of filaments of drug-containing thermoplastic polymers by hot-melt extrusion (HME), and the prospect of connecting the two technologies has been under investigation. The ability to integrate HME and FDM and predict and tailor the filaments’ properties will extend the range of printable polymers/formulations. Hence, this work revises the properties of the most common pharmaceutical-grade polymers used and their effect on extrudability, printability, and printing outcome, providing suitable processing windows for different raw materials. As a result, formulation selection will be more straightforward (considering the characteristics of drug and desired dosage form or release profile) and the processes setup will be more expedite (avoiding or mitigating typical processing issues), thus guaranteeing the success of both HME and FDM. Relevant techniques used to characterize filaments and 3D-printed dosage forms as an essential component for the evaluation of the quality output are also presented.

Iridescent Cellulose Nanocrystal Films Modified with Hydroxypropyl Cellulose

The introduction of polymers into a chiral nematic cellulose nanocrystal (CNC) matrix allows for the tuning of optical and mechanical properties, enabling the development of responsive photonic materials. In this study, we explored the incorporation of hydroxypropyl cellulose (HPC) into a CNC film prepared by slow evaporation. In the composite CNC/HPC thin films, the CNCs adopt a chiral nematic structure, which can selectively reflect certain wavelengths of light to yield a colored film. The color could be tuned across the visible spectrum by changing the concentration or molecular weight of the HPC. Importantly, the composite films were more flexible than pure CNC films with up to a ten-fold increase in elasticity and a decrease in stiffness and tensile strength of up to six times and four times, respectively. Surface modification of the films with methacrylate groups increased the hydrophobicity of the films, and therefore, the water stability of these materials was also improved.

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.

Metformin Hydrochloride and Sitagliptin Phosphate Fixed-Dose Combination Product Prepared Using Melt Granulation Continuous Processing Technology

The development of oral solid dosage forms, such as tablets that contain a high dose of drug(s), requires polymers and other additives to be incorporated at low levels as possible, to keep the final tablet weight low, and, correspondingly, the dosage form size small enough to be acceptable from a patient perspective. Additionally, a multi-step batch-based manufacturing process is usually required for production of solid dosage forms. This study presents the development and production, by twin-screw melt granulation technology, of a high-dose immediate-release fixed-dose combination (FDC) product of metformin hydrochloride (MET) and sitagliptin phosphate (SIT), with drug loads of 80% w/w and 6% w/w, respectively. For an 850/63 mg dose of MET/SIT, the final weight of the caplets was approximately 1063 mg compared with 1143 mg for the equivalent dose in Janumet®, the marketed product. Mixtures of the two drugs and polymers were melt-granulated at temperatures below the individual melting temperatures of MET and SIT (231.65 and 213.89°C, respectively) but above the glass transition temperature or melting temperature of the binder(s) used. By careful selection of binders, and processing conditions, direct compressed immediate-release caplets with desired product profiles were successfully produced. The melt granule formulations before compression showed good flow properties, were larger in particle size than individual starting API materials and were easily compressible. Melt granulation is a suitable platform for developing direct compressible high-dose immediate-release solid dosage forms of FDC products.

The Influence of Viscosity and Non-freezing Water Contents Bounded to Different Hydroxypropyl Celluloses (HPC) and Hydroxypropyl Methylcelluloses (HPMC) on Stability of Acetylsalicylic Acid

The aim of the study was to examine the influence of non-freezing water (NFW) contents bound to hydroxypropyl methylcellulose (HPMC) or hydroxypropyl cellulose (HPC) binary mixtures using acetylsalicylic acid (ASA) as a model moisture-sensitive ingredient. Polysaccharides with significantly different physicochemical properties were mixed with acetylsalicylic acid at a ratio 1:1 (w/w). The measurements of NFW contents of hydrated samples were carried out using differential scanning calorimetry (DSC). In the method used, the dry mass normalized dependency of melting enthalpy (ΔH) and respective contents of water was found to be linear. NFW values were calculated after extrapolation ΔH to 0. For stability studies, HPC/ASA and HPMC/ASA mixtures were stored at 40°C and 75% RH for 5 weeks in the climatic chamber. The ASA hydrolysis was investigated using UV-Vis spectrophotometry. The amounts of NFW calculated for raw HPMC 3 cP and 100,000 cP were 0.49 and 0.42 g g-1, while for polymer and ASA mixtures, prepared from HPC type LF (126 cP) and MF (6300 cP) as well as from HPMC 3 cP and 100,000 cP were 0.23, 0.28 g g-1, 0.21 g g-1, and 0.33 g g-1 respectively. The measured NFW values were connected with appropriate concentrations of unhydrolyzed ASA.

Effects of Processing on a Sustained Release Formulation Prepared by Twin-Screw Dry Granulation

Dry granulation is an indispensable process used to improve the flow property of moisture-sensitive materials. Considering the limitations of currently available dry granulation techniques, it is necessary to develop a novel technique. In this study, a twin-screw dry granulation (TSDG) technology was successfully applied to produce a sustained-release dry granule formulation, which was subsequently compressed into sustained-release tablets. Based on a preliminary study, theophylline was selected as model drug, Klucel^™ EF, Ethocel^™, and magnesium stearate were selected as excipients. A Resolution V Irregular Fraction Design was applied to determine the effect of different processing parameters (screw speed, feeding rate, barrel temperature, and screw configuration) on product properties (flow properties, particle size distribution, and dissolution time). A reliable model was achieved by combining the data obtained, and processing parameters were automatically optimized to attain the setting goal. In general, TSDG was demonstrated to be an alternative method for the preparation of dry granules. The continuous processing nature, simplicity of operation, and ease of optimization made TSDG competitive compared with other conventional dry granulation techniques.

Pharmaceutical Applications of Cellulose Ethers and Cellulose Ether Esters

Cellulose ethers have proven to be highly useful natural-based polymers, finding application in areas including food, personal care products, oil field chemicals, construction, paper, adhesives, and textiles. They have particular value in pharmaceutical applications due to characteristics including high glass transition temperatures, high chemical and photochemical stability, solubility, limited crystallinity, hydrogen bonding capability, and low toxicity. With regard to toxicity, cellulose ethers have essentially no ability to permeate through gastrointestinal enterocytes and many are already in formulations approved by the U.S. Food and Drug Administration. We review pharmaceutical applications of these valuable polymers from a structure-property-function perspective, discussing each important commercial cellulose ether class; carboxymethyl cellulose, methyl cellulose, hydroxypropylcellulose, hydroxypropyl methyl cellulose, and ethyl cellulose, and cellulose ether esters including hydroxypropyl methyl cellulose acetate succinate and carboxymethyl cellulose acetate butyrate. We also summarize their syntheses, basic material properties, and key pharmaceutical applications.

The development of sustained release drug delivery platforms using melt-extruded cellulose-based polymer blends

OBJECTIVES

This research examined the application of hot melt extrusion (HME) in the preparation of matrix formulations containing hydroxypropyl cellulose (HPC) as a base polymer in combination with methyl cellulose (MC) and hydroxypropyl methylcellulose (HPMC).

METHODS

The limit to which formulations could control drug release under varying paddle speeds, high alcohol environments and high and low drug loads was investigated on a Caleva 10 ST dissolution tester. Rheological studies and hot plate imaging highlighted the impact of thermoresponsive polymers on drug release. The rate and percentage release of drug were analysed using a one-way ANOVA and Tukey's HSD test.

KEY FINDINGS

No significant differences in the amount of drug released were calculated as a result of paddle speed variation or in the presence of 40% v/v ETOH. The phase separation effects of temperature-sensitive polymers HPC and MC and the characteristic gel shrinkage and fluid expulsion were shown to be contributing factors. The use of the partition activity, α, identified the extent to which formulations were affected by phase separation.

CONCLUSION

Hot melt extrusion was successfully used to manufacture cellulose-based formulations. Thermoresponsive polymers HPC and MC significantly impacted drug release properties.

Quality-by-Design II: Application of Quantitative Risk Analysis to the Formulation of Ciprofloxacin Tablets

Qualitative risk assessment methods are often used as the first step to determining design space boundaries; however, quantitative assessments of risk with respect to the design space, i.e., calculating the probability of failure for a given severity, are needed to fully characterize design space boundaries. Quantitative risk assessment methods in design and operational spaces are a significant aid to evaluating proposed design space boundaries. The goal of this paper is to demonstrate a relatively simple strategy for design space definition using a simplified Bayesian Monte Carlo simulation. This paper builds on a previous paper that used failure mode and effects analysis (FMEA) qualitative risk assessment and Plackett-Burman design of experiments to identity the critical quality attributes. The results show that the sequential use of qualitative and quantitative risk assessments can focus the design of experiments on a reduced set of critical material and process parameters that determine a robust design space under conditions of limited laboratory experimentation. This approach provides a strategy by which the degree of risk associated with each known parameter can be calculated and allocates resources in a manner that manages risk to an acceptable level.

Evaluation of the recrystallization kinetics of hot-melt extruded polymeric solid dispersions using an improved Avrami equation

The recrystallization of an amorphous drug in a solid dispersion system could lead to a loss in the drug solubility and bioavailability. The primary objective of the current research was to use an improved kinetic model to evaluate the recrystallization kinetics of amorphous structures and to further understand the factors influencing the physical stability of amorphous solid dispersions. Amorphous solid dispersions of fenofibrate with different molecular weights of hydroxypropylcellulose, HPC (Klucel™ LF, EF, ELF) were prepared utilizing hot-melt extrusion technology. Differential scanning calorimetry was utilized to quantitatively analyze the extent of recrystallization in the samples stored at different temperatures and relative humidity (RH) conditions. The experimental data were fitted into the improved kinetics model of a modified Avrami equation to calculate the recrystallization rate constants. Klucel LF, the largest molecular weight among the HPCs used, demonstrated the greatest inhibition of fenofibrate recrystallization. Additionally, the recrystallization rate (k) decreased with increasing polymer content, however exponentially increased with higher temperature. Also k increased linearly rather than exponentially over the range of RH studied.

Controlled porosity solubility modulated osmotic pump tablets of gliclazide

A system that can deliver drug at a controlled rate is very important for the treatment of various chronic diseases such as diabetes, asthma, and heart disease. Poorly water-soluble drug with pH-dependent solubility such as gliclazide (GLZ) offers challenges in the controlled-release formulation because of low dissolution rate and poor bioavailability. Solid dispersion (SD) of GLZ consisted of hydroxypropyl cellulose (HPC-SSL) as a polymeric solubilizer was manufactured by hot melt extrusion (HME) technology. Then, controlled porosity osmotic pump (CPOP) tablet of gliclazide was designed to deliver drug in a controlled manner up to 16 h. The developed formulation was optimized for type and level of pore former and coating weight gain. The optimized formulation was found to exhibit zero order kinetics independent of pH and agitation speed but depends on osmotic pressure of dissolution media indicated that mechanism of drug release was osmotic pressure. The in vivo performance prediction of developed formulation using convolution approach revealed that the developed formulation was superior to the existing marketed extended-release formulation in terms of attaining steady state plasma levels and indicated adequate exposure in translating hypoglycemic response. The prototype solubilization method combined with controlled porosity osmotic pump based technique could provide a unique way to increase dissolution rate and bioavailability of many poorly water-soluble, narrow therapeutic index drugs used in diabetes, cardiovascular diseases, etc.

Evaluation of hot-melt extrusion technique in the preparation of HPC matrices for prolonged release

The aim of the work was to explore the potential of hot-melt extrusion (HME) for preparing hydroxypropyl cellulose (HPC)-based prolonged-release matrices intended for oral administration. For this purpose, compressed and extruded systems, either composed of polymer only or containing different amounts of a model drug (theophylline or ketoprofen), were compared. The overall morphological/physical changes of the systems following interaction with water indicated that the manufacturing process would not exert a major influence on the swelling behavior of the polymeric matrices. On the other hand, the release rate was generally higher from HME systems probably due to an increase of the drug dissolution rate, which is in agreement with the relevant DSC data (loss of drug cristallinity). However, the technological characteristics of the matrices and the maximum drug load were demonstrated to depend on the mode of interaction of the active ingredient with the molten polymer. In this respect, the formation of a composite material from ketoprofen and HPC, when mixed in specific ratios, was supposed to explain the differences observed between compressed and extruded systems in terms of morphological characteristics, hydration/swelling and release. The obtained results support the possibility of exploiting the advantages offered by HME technique, above all the potential for continuous manufacturing, in the preparation of prolonged-release swellable matrices based on a cellulose derivative.

Design, development, and optimization of polymeric based-colonic drug delivery system of naproxen

The aim of present investigation deals with the development of time-dependent and pH sensitive press-coated tablets for colon specific drug delivery of naproxen. The core tablets were prepared by wet granulation method then press coated with hydroxypropyl cellulose (HPC) or Eudragit RSPO : RLPO mixture and further coated with Eudragit S-100 by dip immerse method. The in vitro drug release study was conducted in different dissolution media such as pH 1.2, 6.8, and 7.4 with or without rat caecal content to simulate GIT conditions. Surface morphology and cross-sectional view of the tablets were visualized by scanning electron microscopy (SEM). All prepared batches were in compliance with the pharmacopoeial standards. The tablets which are compression coated with HPC followed by Eudragit S-100 coated showed highest in vitro drug release of 98.10% in presence of rat caecal content. The SEM of tablets suggested that the number of pores got increased in pH 7.4 medium followed by dissolution of coating layer. The tablets coat erosion study suggested that the lag time depends upon the coating concentrations of polymers. A time-dependent hydrophilic polymer and pH sensitive polymer based press-coated tablets of naproxen were promising delivery for colon targeting.

Low-viscosity hydroxypropylcellulose (HPC) grades SL and SSL: versatile pharmaceutical polymers for dissolution enhancement, controlled release, and pharmaceutical processing

Hydroxypropylcellulose (HPC)-SL and -SSL, low-viscosity hydroxypropylcellulose polymers, are versatile pharmaceutical excipients. The utility of HPC polymers was assessed for both dissolution enhancement and sustained release of pharmaceutical drugs using various processing techniques. The BCS class II drugs carbamazepine (CBZ), hydrochlorthiazide, and phenytoin (PHT) were hot melt mixed (HMM) with various polymers. PHT formulations produced by solvent evaporation (SE) and ball milling (BM) were prepared using HPC-SSL. HMM formulations of BCS class I chlorpheniramine maleate (CPM) were prepared using HPC-SL and -SSL. These solid dispersions (SDs) manufactured using different processes were evaluated for amorphous transformation and dissolution characteristics. Drug degradation because of HMM processing was also assessed. Amorphous conversion using HMM could be achieved only for relatively low-melting CBZ and CPM. SE and BM did not produce amorphous SDs of PHT using HPC-SSL. Chemical stability of all the drugs was maintained using HPC during the HMM process. Dissolution enhancement was observed in HPC-based HMMs and compared well to other polymers. The dissolution enhancement of PHT was in the order of SE>BM>HMM>physical mixtures, as compared to the pure drug, perhaps due to more intimate mixing that occurred during SE and BM than in HMM. Dissolution of CPM could be significantly sustained in simulated gastric and intestinal fluids using HPC polymers. These studies revealed that low-viscosity HPC-SL and -SSL can be employed to produce chemically stable SDs of poorly as well as highly water-soluble drugs using various pharmaceutical processes in order to control drug dissolution.

Klucel™ EF and ELF polymers for immediate-release oral dosage forms prepared by melt extrusion technology

The objective of this research work was to evaluate Klucel™ hydroxypropylcellulose (HPC) EF and ELF polymers, for solubility enhancement as well as to address some of the disadvantages associated with solid dispersions. Ketoprofen (KPR), a Biopharmaceutics Classification System class II drug with poor solubility, was utilized as a model compound. Preliminary thermal studies were performed to confirm formation of a solid solution/dispersion of KPR in HPC matrix and also to establish processing conditions for hot-melt extrusion. Extrudates pelletized and filled into capsules exhibited a carrier-dependent release with ELF polymer exhibiting a faster release. Tablets compressed from milled extrudates exhibited rapid release owing to the increased surface area of the milled extrudate. Addition of mannitol (MNT) further enhanced the release by forming micro-pores and increasing the porosity of the extrudates. An optimized tablet formulation constituting KPR, MNT, and ELF in a 1:1:1 ratio exhibited 90% release in 15 min similar to a commercial capsule formulation. HPC polymers are non-ionic hydrophilic polymers that undergo polymer-chain-length-dependent solubilization and can be used to enhance solubility or dissolution rate of poorly soluble drugs. Dissolution/release rate could be tailored for rapid-release applications by selecting a suitable HPC polymer and altering the final dosage form. The release obtained from pellets was carrier-dependent and not drug-dependent, and hence, such a system can be effectively utilized to address solubility or precipitation issues with poorly soluble drugs in the gastrointestinal environment.

Radial die-wall pressure as a reliable tool for studying the effect of powder water activity on high speed tableting

The effect of moisture as a function of water activity (Aw) on the compaction process is important to understand particle/water interaction and deformation. Studying powder/moisture interaction under pressure with radial die-wall pressure (RDWP) tool was never done. The aim of our study was to use this tool to study this interaction at high compression pressure and speed. Moreover, the effect of changing ejection cam angle (EA) of the machine on ejection force (EF) was investigated. Also, a new tool for prediction of tablet sticking was proposed. Materials with different deformation behaviors stored at low and high moisture conditions were used. Compaction simulation guided by modeling was applied. High Aw resulted in a low residual die-wall pressure (RDP) for all materials, and a high maximum die-wall pressure (MDP) for plastic materials, p < 0.05. This was due to the lubricating and plasticizing effects of water, respectively. However, microcrystalline cellulose showed capping at high Aw and compaction pressure. By increasing compression pressure at high Aw for all materials, effective fall time (EFT) was increased, p < 0.05, showing tendency for sticking. Increasing EA caused an increase of friction and EF for powders, p < 0.05. RDWP was a useful tool to understand particle/moisture interaction under pressure.

FIP position paper on qualification of paddle and basket dissolution apparatus

The qualification process for ensuring that a paddle or basket apparatus is suitable for its intended use is a highly debated and controversial topic. Different instrument qualification and suitability methods have been proposed by the pharmacopeias and regulatory bodies. In an effort to internationally harmonize dissolution apparatus suitability requirements, the International Pharmaceutical Federation's (FIP) Dissolution/Drug Release Special Interest Group (SIG) reviewed current instrument suitability requirements listed in the US, European, and Japanese pharmacopeias and the International Conference on Harmonization (ICH) Topic Q4B on harmonization of pharmacopoeial methods, in its Annex 7, Dissolution Test General. In addition, the SIG reviewed the Food and Drug Administration (FDA) Draft Guidance for Industry, "The Use of Mechanical Calibration of Dissolution Apparatus 1 and 2-Current Good Manufacturing Practice (CGMP)" and the related ASTM Standard E2503-07. Based on this review and several in-depth discussions, the FIP Dissolution/Drug Release SIG recommends that the qualification of a dissolution test instrument should be performed following the calibration requirements as indicated in the FDA (draft) guidance. If additional system performance information is desired, a performance verification test using US Pharmacopeia Reference Standard tablet or an established in-house reference product can be conducted. Any strict requirement on the use of a specific performance verification test tablet is not recommended at this time.