Melt extrusion process for adjusting drug release of poorly water soluble drug felodipine using different polymer matrices

Characterization and Dissolution Mechanism of Low-Molecular-Weight Organic Acids or Inorganic Mesoporous Particle-Based Piperine Amorphous Solid Dispersions

The objective of the current study is to prepare amorphous solid dispersions (ASDs) containing piperine (PIP) by utilizing organic acid glycyrrhizic acid (GA) and inorganic disordered mesoporous silica 244FP (MSN/244FP) as carriers and to investigate their dissolution mechanism. The physicochemical properties of ASDs were characterized with scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC). Fourier transform infrared spectroscopy (FTIR) and one-dimensional proton nuclear magnetic resonance (1H NMR) studies collectively proved that strong hydrogen-bonding interactions formed between PIP and the carriers in ASDs. Additionally, molecular dynamic (MD) simulation was conducted to simulate and predict the physical stability and dissolution mechanisms of the ASDs. Interestingly, it revealed a significant increase in the dissolution of amorphous PIP in ASDs in in vitro dissolution studies. Rapid dissolution of GA in pH 6.8 medium resulted in the immediate release of PIP drugs into a supersaturated state, acting as a dissolution-control mechanism. This exhibited a high degree of fitting with the pseudo-second-order dynamic model, with an R2 value of 0.9996. Conversely, the silanol groups on the outer surface of the MSN and its porous nanostructures enabled PIP to display a unique two-step drug release curve, indicating a diffusion-controlled mechanism. This curve conformed to the Ritger-Peppas model, with an R2 > 0.9. The results obtained provide a clear evidence of the proposed transition of dissolution mechanism within the same ASD system, induced by changes in the properties of carriers in a solution medium of varying pH levels.

Amorphous solid dispersion of a binary formulation with felodipine and HPMC for 3D printed floating tablets

This study focuses on the combination of three-dimensional printing (3DP) and amorphous solid dispersion (ASD) technologies for the manufacturing of gastroretentive floating tablets. Employing hot melt extrusion (HME) and fused deposition modeling (FDM), the study investigates the development of drug-loaded filaments and 3D printed (3DP) tablets containing felodipine as model drug and hydroxypropyl methylcellulose (HPMC) as the polymeric carrier. Prior to fabrication, solubility parameter estimation and molecular dynamics simulations were applied to predict drug-polymer interactions, which are crucial for ASD formation. Physical bulk and surface characterization complemented the quality control of both drug-loaded filaments and 3DP tablets. The analysis confirmed a successful amorphous dispersion of felodipine within the polymeric matrix. Furthermore, the low infill percentage and enclosed design of the 3DP tablet allowed for obtaining low-density systems. This structure resulted in buoyancy during the entire drug release process until a complete dissolution of the 3DP tablets (more than 8 h) was attained. The particular design made it possible for a single polymer to achieve a zero-order controlled release of the drug, which is considered the ideal kinetics for a gastroretentive system. Accordingly, this study can be seen as an advancement in ASD formulation for 3DP technology within pharmaceutics.

Factors That Influence Sustained Release from Hot-Melt Extrudates

Hot-melt extrusion is a well-established tool in the pharmaceutical industry, mostly implemented to increase the solubility of poorly soluble drugs. A less frequent application of this technique is to obtain formulations with extended release. This study investigated the influence of polymer choice, drug loading, milling and hydrodynamics on the release of a model drug, flurbiprofen, from sustained-release hot-melt extrudates with Eudragit polymers. The choice of polymer and degree of particle size reduction of the extrudate by milling were the two key influences on the release profile: the percentage release after 12 h varied from 6% (2 mm threads) to 84% (particle size <125 µm) for Eudragit RL extrudates vs. 4.5 to 62% for the corresponding Eudragit RS extrudates. By contrast, the release profile was largely independent of drug loading and robust to hydrodynamics in the dissolution vessel. Thus, hot-melt extrusion offers the ability to tailor the release of the API to the therapeutic indication through a combination of particle size and polymer choice while providing robustness over a wide range of hydrodynamic conditions.

Customized 3D-printed hollow capsular device filled with norfloxacin-loaded micropellets for controlled-release delivery

Pharmacotherapy has become more focused on the personalized treatment of patients with various diseases. This field of pharmacology and pharmacogenomics focuses on developing drug delivery systems designed to address the unique characteristics of individual patients. Three-dimensional printing technology can be used to fabricate personalized drug delivery systems with desired release properties according to patient needs. Norfloxacin (NOR)-loaded micropellets (MPs) were fabricated and filled inside a stereolithography (SLA) 3D printing technology-mediated hollow capsular device in accordance with a standard size of 09 (8.4 mm length × 2.70 mm diameter). The prepared 3D-printed hollow capsular device filled with pristine NOR and NOR-loaded MPs were characterized in terms of both in vitro and in vivo means. MPs with the particle size distribution of 1540.0 ± 26 µm showed 95.63 ± 2.0% NOR content with pellet-shaped surface morphology. The in vitro release profile showed an initial lag phase of approximately 30 min, followed by the sustained release of NOR from MPs from the 3D-printed hollow capsular device. The pharmacokinetic profile showed prolonged T_max, AUC, and evidence of good RBA of NOR compared to pure NOR after a single oral administration in the experimental animal model. The overall results confirm the feasibility of SLA-mediated 3D printing technology for preparing customized solid oral unit dosage carriers that can be filled with pure NOR- and NOR-loaded MPs with controlled-release delivery features.

Overview of nanoparticulate strategies for solubility enhancement of poorly soluble drugs

Poor aqueous solubility and poor bioavailability are major issues with many pharmaceutical industries. By some estimation, 70-90% drug candidates in development stage while up-to 40% of the marketed products are poorly soluble which leads to low bioavailability, reduced therapeutic effects and dosage escalation. That's why solubility is an important factor to consider during design and manufacturing of the pharmaceutical products. To-date, various strategies have been explored to tackle the issue of poor solubility. This review article focuses the updated overview of commonly used macro and nano drug delivery systems and techniques such as micronization, solid dispersion (SD), supercritical fluid (SCF), hydrotropy, co-solvency, micellar solubilization, cryogenic technique, inclusion complex formation-based techniques, nanosuspension, solid lipid nanoparticles, and nanogels/nanomatrices explored for solubility enhancement of poorly soluble drugs. Among various techniques, nanomatrices were found a promising and impeccable strategy for solubility enhancement of poorly soluble drugs. This article also describes the mechanism of action of each technique used in solubilization enhancement.

Drug Amorphous Solid Dispersions Based on Poly(vinyl Alcohol): Evaluating the Effect of Poly(propylene Succinate) as Plasticizer

Although significant actions have been taken towards the utilization of poly(vinyl alcohol) (PVA) in the preparation of drug amorphous solid dispersions (ASDs) using fusion-based techniques (such as melt-quench cooling and hot-melt extrusion), several drawbacks regarding its rather high melting temperature and its thermal degradation profile make the use of the polymer extremely challenging. This is especially important when the active pharmaceutical ingredient (API) has a lower melting temperature (than PVA) or when it is thermally labile. In this vein, a previous study showed that newly synthesized polyester-based plasticizers may improve the processability and the thermal properties of PVA. However, the effects of such polyester-based plasticizers on the drug’s physicochemical and pharmaco-technical properties are yet unknown. Hence, the aim of the present study is to extend our previous findings and evaluate the use of poly(propylene succinate) (PPSu, i.e., the most promising plasticizer in regard to PVA) in the preparation of drug-loaded PVA-based ASDs. Dronedarone (DRN), a poorly water-soluble API, was selected as a model drug, and drug ASDs (using either neat PVA or PVA-PPSu) were prepared using the melt-mixing/quench cooling approach at low melting temperatures (i.e., 170 °C). DSC and pXRD analysis showed that a portion of the API remained crystalline in the ASDs prepared only with the use of neat PVA, while the samples having PPSu as a plasticizer were completely amorphous. Further evaluation with ATR-FTIR spectroscopy revealed the formation of significant intermolecular interactions between the API and the PVA-PPSu matrix, which could explain the system’s physical stability during storage. Finally, dissolution studies, conducted under nonsink conditions, revealed that the use of PVA-PPSu is able to maintain DRN’s sustained supersaturation for up to 8 h.

Sustained-Release Solid Dispersion of High-Melting-Point and Insoluble Resveratrol Prepared through Hot Melt Extrusion to Improve Its Solubility and Bioavailability

This study aimed to prepare a sustained-release solid dispersion of poorly water-soluble resveratrol (RES) with high melting point in a single hot melt extrusion step. A hydrophobic-hydrophilic polymeric blend (Eudragit RS and PEG6000) was used to control the release of RES. With the dispersive mixing and high shear forces of hot melt extrusion, the thermodynamic properties and dispersion of RES were changed to improve its solubility. The effects of the formulation were investigated through univariate analysis to optimize the preparation of the sustained-release solid dispersion. In vitro and in vivo studies were performed to evaluate the prepared RES/RS/PEG6000 sustained-release solid dispersion. The physical state of the solid dispersion was characterized using differential scanning calorimetry and X-ray diffraction. Surface properties of the dispersion were visualized using scanning electron microscopy, and the chemical interaction between RES and excipients was detected through Fourier-transform infrared spectroscopy. Results suggested that the optimized sustained-release solid dispersion was obtained when the mass ratio of RES-polymeric blend was 1:5, the ratio of PEG6000 was 35%, the barrel temperature was 170 °C, and the screw speed was 80 rpm. In vitro studies demonstrated that the solid dispersion showed a good sustained release effect. The cumulative release of RES reached 82.42% until 12 h and was fit by the Weibull model. In addition, the saturated solubility was 2.28 times higher than that of the bulk RES. In vitro studies demonstrated that the half-life increased from 3.78 to 7.09 h, and the bioavailability improved to 140.38%. The crystalline RES was transformed into the amorphous one, and RES was highly dispersed in the polymeric blend matrix.

Drug-Loaded Hydrogels for Intraocular Lenses with Prophylactic Action against Pseudophakic Cystoid Macular Edema

Pseudophakic cystoid macular edema (PCME), caused by chronic inflammation, is the most common cause of visual impairment in the medium-term after cataract surgery. Therefore, the prophylactic topical administration of combined steroidal and non-steroidal anti-inflammatory drugs is commonly done. Drug-eluting intraocular lenses (IOLs) gained interest as an efficient way to overcome the compliance issues related to the use of ocular drops without the need for additional surgical steps. The incorporation of functional monomers and molecular imprinting were herein applied to design hydrogels suitable as IOLs and able to co-deliver steroidal (dexamethasone sodium phosphate) and non-steroidal (bromfenac sodium) drugs. The incorporation of N-(2-aminopropyl) methacrylamide (APMA) increased the drug uptake and improved the in vitro release kinetics. Imprinting with bromfenac resulted in a decreased drug release due to permanent drug bonding, while imprinting with dexamethasone increased the amount of dexamethasone released after dual-drug loading. The application of a mathematical model to predict the in vivo drug release behavior suggests the feasibility of achieving therapeutic drug concentrations of bromfenac and dexamethasone in the aqueous humor for about 2 and 8 weeks, respectively, which is compatible with the current topical prophylaxis after cataract surgery.

Hot-Melt Extrusion: a Roadmap for Product Development

Hot-melt extrusion has found extensive application as a feasible pharmaceutical technological option over recent years. HME applications include solubility enhancement, taste masking, and sustained drug release. As bioavailability enhancement is a hot topic of today's science, one of the main applications of HME is centered on amorphous solid dispersions. This review describes the most significant aspects of HME technology and its use to prepare solid dispersions as a drug formulation strategy to enhance the solubility of poorly soluble drugs. It also addresses molecular and thermodynamic features critical for the physicochemical properties of these systems, mainly in what concerns miscibility and physical stability. Moreover, the importance of applying the Quality by Design philosophy in drug development is also discussed, as well as process analytical technologies in pharmaceutical HME monitoring, under the current standards of product development and regulatory guidance. Graphical Abstract.

Enabling modular dosage form concepts for individualized multidrug therapy: Expanding the design window for poorly water-soluble drugs

Multidrug dosage forms (aka combination dosage forms, polypills, etc.) create value for patients through reduced pill burdens and simplified administration to improve adherence to therapy. Enhanced flexibility of multidrug dosage forms would provide further opportunities to better match emerging needs for individualized therapy. Through modular dosage form concepts, one approach to satisfy these needs is to adapt multidrug dosage forms to a wider variety of drugs, each with a variety of doses and release profiles. This study investigates and technically explores design requirements for extending the capability of modular multidrug dosage form concepts towards individualization. This builds on our recent demonstration of independent tailoring of dose and drug release, which is here extended towards poorly water-soluble drugs. The challenging design requirement of carrying higher drug loads in smaller volumes to accommodate multiple drugs at their clinical dose is here met regarding dose and release performance. With a modular concept, we demonstrate high precision (<5% RSD) in dose and release performance of individual modules containing felodipine or naproxen in Kollidon VA64 at both a wide drug loading range (5% w/w and 50% w/w drug) and a small module size (3.6 mg). In a forward-looking design-based discussion, further requirements are addressed, emphasizing that reproducible individual module performance is predictive of dosage form performance, provided the modules are designed to act independently. Therefore, efforts to incorporate progressively higher drug loads within progressively smaller module volumes will be crucial to extend the design window further towards full flexibility of future dosage forms for individualized multidrug therapy.

Synthesis of PEG-4000-co-poly (AMPS) nanogels by cross-linking polymerization as highly responsive networks for enhancement in meloxicam solubility

Poor solubility is an ongoing issue and the graph of poorly soluble drugs has increased markedly which critically affect their dissolution, bioavailability, and clinical effects. This common issue needs to be addressed, for this purpose a series of polyethylene glycol (PEG-4000) based nanogels were developed by free radical polymerization technique to enhance the solubility, dissolution, and bioavailability of poorly soluble drug meloxicam (MLX), as improved solubility is the significant application of nanosystems. Developed nanogels formulations were characterized by FTIR, XRD, SEM, zeta sizer, percent equilibrium swelling, drug loaded content (DLC), drug entrapment efficiency (DEE), solubility studies, and in vitro dissolution studies. Furthermore, cytotoxicity studies were conducted in order to determine the bio-compatibility of the nanogels drug delivery system to biological environment. Nanogels particle size was found to be 156.19 ± 09.33 d.nm. Solubility study confirmed that the solubility of poorly soluble drug MLX was significantly enhanced up to 36 folds as compared to reference product (Mobic^®). The toxicity study conducted on rabbits and MTT assay endorsed the safety of the developed nanogels formulations to the biological system.

Fabrication and characterisation of melt-extruded chitosan/keratin/PCL/PEG drug-eluting sutures designed for wound healing

Diclofenac potassium loaded sutures based upon PEG/PCL/chitosan-keratin blends were fabricated using the hot-melt extrusion technique. Polymer sutures were evaluated based on their physical, thermal and mechanical properties, while the drug-eluting sutures were evaluated for drug release properties. Lastly, the performance of the drug-loaded sutures in the contact with the human keratinocyte cell line HaCat were assessed. Results showed that the sutures extruded homogeneously at a temperature of 63 ± 1 °C providing a uniform thickness of fibres. Analysis by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) showed that completely amorphous and miscible solid dispersions were created. Fourier transform infrared (FTIR) spectroscopy indicated that the presence of hydrogen bonds between the polymers improved material miscibility. Tensile properties of the sutures were clearly affected by the PEG, chitosan and keratin additions. The optimal formulation of tensile strength was obtained when PCL/PEG/chitosan-keratin were combined at a ratio of 80/19/1 w/w. Rapid and sustained drug release rates were achieved with the PEG/PCL/chitosan/keratin blends at various combinations. The composite of PCL/PEG/chitosan-keratin with 30 wt% of diclofenac potassium also exhibited high cell viability and wound healing rates in vitro cytotoxicity testing. The anti-inflammatory properties imparted by the PCL/PEG/chitosan/keratin/drug sutures may further the use of composite sutures for wound healing in clinical settings.

Spectroscopic Methodology and Molecular Docking Studies on Changes in Binding Interaction of Felodipine with Bovine Serum Albumin Induced by Cocrystallization with β-Resorcylic Acid

In the present study, a novel cocrystal of felodipine (FEL) and β-resorcylic acid (βRA) was developed. We specially focused on the change of binding pattern with bovine serum albumin (BSA) induced by cocrystallization of FEL with βRA. The solid characterizations and density functional theory (DFT) simulation verified that FEL-βRA cocrystal formed in equimolar ratio (1 : 1 M ratio) through C=O^…H-O hydrogen bond between C=O group in FEL and O-H group in βRA. The binding interactions between FEL-βRA system and BSA were studied using fluorescence spectral and molecular docking methods. Two guest molecule systems, including a physical mixture of FEL and βRA and FEL-βRA cocrystal were performed binding to BSA in molecular docking. According to the K_b and binding energy, the supramolecular form of FEL-βRA system was retained during binding to BSA. Molecular docking simulation suggested that FEL and its cocrystal inserted into the subdomain IIIA (site II') of BSA. The interactions between FEL and BSA including hydrogen bonding with ASN390 residue and intermolecular hydrophobic interactions with LEU429 and LEU452 residues. However, the size of supramolecular FEL-βRA better matched that of active cavity of BSA; the cocrystal is closely bound to BSA through hydrogen bonding with ASN390 residue and intermolecular hydrophobic interactions with LEU429, VAL432, LEU452 and ILE387 residues. This change on binding affinity of FEL to BSA induced by cocrystallization with βRA provided theoretical basis to evaluate the transportation, distribution and metabolism of cocrystal drug.

The preparation of felodipine/zein amorphous solid dispersions and in vitro evaluation using a dynamic gastrointestinal system

ABSTRCT Felodipine has been widely used as a poorly water-soluble model drug for various studies to improve its oral bioavailability and in vivo efficacy. In this study, we developed amorphous solid dispersions (ASDs) via spray drying to enhance the bioavailability of felodipine through using natural zein protein as a novel polymeric excipient. The solid state characterization results demonstrated a single glass transition temperature (T_g ) around 128.6 °C and good physical stability post 3 months accelerated study under the condition of 40 °C and 75% relative humidity (RH), which is possibly accounted for the molecular immobilization and hydrogen bonding interactions between felodipine and zein. By combining the in vitro dissolution study with TIM-1 gastrointestinal simulation investigation, it is indicated that felodipine was rapidly released from the ASD in 30 mins, and the supersaturation of felodipine was well maintained over 6 h, which resulted in a significant enhancement of felodipine bioavailability during simulated digestive processes in the upper GI tract. This study suggests that spray drying combined with natural excipient zein is an efficient formulation strategy for the development of ASDs with enhanced aqueous solubility and bioavailability.

Crystallization tendency of APIs possessing different thermal and glass related properties in amorphous solid dispersions

The correlation between glass forming ability (GFA) and several thermophysical or physicochemical properties of APIs with the formation and the physical stability of amorphous solid dispersions (ASDs) was evaluated in the present study. Eight poorly water-soluble APIs belonging in different GFA classes (i.e. a) GFA Class I: Carbamazepine, CBZ, b) GFA Class II: Agomelatine, AGO, Aprepitant, APT, Rivaroxaban, RIV, and c) GFA Class III: Indomethacin, IND, Pioglitazone, PIO, Piroxixam, PIR, and Simvastatin, SIM) were tested, in addition to six commonly used matrix-carriers (namely povidone, PVP, hydroxypropyl cellulose, HPC-SL, copovidone, coPVP, Soluplus®, SOL, and gelatin) in order to prepared ASDs via film casting approach. Results using polarized light microscopy (PLM) showed a similar drug crystallization tendency from ASDs independently of their GFA classification, glass stability or glass fragility. X-ray diffraction analysis verified the formation and the physical stability of ASD (independently of GFA class) when a suitable matrix-carrier was selected (i.e. SOL for AGO, RIV and SIM, PVP for APT, CBZ and IND, coPVP for PIO and gelatin for PIR). Further attempts to correlate some physicochemical properties (i.e. component's binding affinity and miscibility) with the formation and the crystallization tendency of the prepared ASDs showed no apparent correlation in regards to the different drug GFA classes. Finally, the evaluation of molecular interactions via FTIR analysis also failed to adequately distinguish the differences in regards to the formation and the physical stability of the prepared systems.

Novel Hot Melt Extruded Matrices of Hydroxypropyl Cellulose and Amorphous Felodipine-Plasticized Hydroxypropyl Methylcellulose as Controlled Release Systems

Hydroxypropyl methylcellulose (HPMC) is a hydrophilic retarding-release polymer with the limited application in hot melt extrusion (HME) due to its high glass transition temperature (T_g 181-191°C) and melt viscosity. The aim of this study is to develop hot melt extruded matrices using hydroxypropyl cellulose (HPC) and felodipine (FLDP) with HPMC for controlled release and explore the relations of their specialty, processability, and structure with the product properties. Results showed that FLDP/HPC_EF/HPMC can be extruded at 160°C with torques not more than 0.5 N·m. The extruded matrices of FLDP/HPC_EF/HPMC_K15M (10:45:45 and 30:35:35) achieved the controlled release for 24 h. Rheological behaviors demonstrated that HPC_EF and FLDP were miscible with HPMC_K15M, attaining maximum 30% FLDP soluble in the molten mixtures. HPC_EF and FLDP decreased the complex viscosity and plasticized HPMC_K15M to improve the extrusion processing. DSC and FT-IR indicated that the molten soluble FLDP was amorphous in the extruded matrices by hydrogen bonding with HPC_EF/HPMC_K15M. SEM/energy-dispersive X-ray microanalysis illustrated that the microstructure of extrudates was surface dense and interior loose, and FLDP was homogenously dispersed. Three-point bending test revealed that the plasticizers of HPC_EF and FLDP contributed differently to the mechanical properties. HPC_EF decreased the flexural modulus of HPMC_K15M while that of HPC_EF/HPMC_K15M was increased by FLDP. Besides controlled release, low moisture absorption and enhanced stability were also the correlated achievements. Therefore, HPC_EF-combined poorly water-soluble drugs to plasticize HPMC_K15M provide an alternative novel potential approach to realize the controlled-release delivery via HME.

A novel insight into fluid bed melt granulation: Temperature mapping for the determination of granule formation with the in-situ and spray-on techniques

The in-line control of pharmaceutical processes has become a necessary tool for the evaluation and follow-up of pharmaceutical dosage forms. In this study, a novel approach to the evaluation of conditions established in a conical fluid bed granulator during the in-situ and spray-on fluid bed melt granulation (FBMG) techniques was developed. The determination of temperature mappings allowed the characterization of the critical zones during the melt granulation and the prediction of the volume of the wetting zone, hence enabling the identification of the areas of optimal granule growth. Two grades of polyethylene glycol (PEG 2000 and 6000) were used as meltable binders in three binder spraying rates and droplet size fractions for spray-on and three binder particle sizes and contents for in-situ. The results showed the presence of intense heat exchange in the bottom of the bed during the in-situ technique and under the spraying nozzle during the spray-on technique, identified as the wetting zone. Isotherm maps enabled the identification of the transition between the wetting, cooling and consolidation zones for the spray-on and the cooling zone for the in-situ technique. The shape and volume of the wetting zone was highly dependent on binder spraying rate and spraying pressure for spray-on and binder particle size and content for in-situ FBMG. Granule size and size distribution were correlated to the volume of the wetting zone and an optimized wetting volume interval was determined for both spray-on and in-situ techniques for the optimal quality attributes of the granules.

The applicability of pharmaceutical polymeric blends for the fused deposition modelling (FDM) 3D technique: Material considerations-printability-process modulation, with consecutive effects on in vitro release, stability and degradation

The three dimensional printing (3DP) in the pharmaceutical domain constitutes an alternative, innovative approach compared to the conventional production methods. Fused deposition modelling (FDM), is a simple, cost-effective 3DP technique, however the range of pharmaceutical excipients that can be applied for this methodology is restricted. The study set to define the requirements of the FDM printability, using as technical support custom made, pharmaceutical polymer based filaments and to evaluate if these new dosage forms can live up to the current GMP/GCP quality standards. Formulation rationale was assessed in accordance to the apparatus functionality. Blends were pre-screened based on the processability under the API (carvedilol) thermogravimetric analysis determined critical limit. The technological process implied the use of FDM coupled with hot melt extrusion (HME), while printability was defined by means of thermal, rheological and mechanical measurements. From the pharmaceutical standpoint, the consistency of the in vitro dissolution kinetics was monitored 'at release' and 'in stability', while the print process impact was evaluated based on the previously determined processability potential. Results showed that FDM printability is multifactorial, with brittleness and melt viscosity as primary limitation factors. The increase in shear-thinning and flexural modulus can enable broader processability intervals, which in turn proved to be essential in limiting degradation product formation. The 3DP tablets released the API in an extended rate, however the temperature and humidity along production and storage should be carefully considered as it may affect the final product quality in time. In conclusion, HME + FDM can be considered as an alternative production methodology, with prospects of applicability in the clinical sector, however for some formulations extensive packaging development will be necessary before confirming their suitability.

Polyvinylpyrrolidone affects thermal stability of drugs in solid dispersions

The present study explores the hypothesis that a polymer can affect the thermal stability of a drug in solid polymer-drug dispersions. The hypothesis is tested in a systematic fashion by combining isoconversional kinetic analysis with thermogravimetric measurements on several solid dispersions. Experimental systems involve three drugs: indomethacin (IMC), felodipine (FD), and nifedipine (ND) and their solid dispersions with polyvinylpyrrolidone (PVP). It is found that PVP stabilizes IMC but destabilizes FD and ND. Isoconversional kinetic analysis provides insights into the origin of the observed effects. The enhanced thermal stability of IMC in the PVP matrix is associated with an increase in the activation energy of the respective degradation process. A detrimental effect of the PVP matrix on the stability of FD and ND has been linked to a decrease in the activation energy and an increase in the preexponential factor, respectively. The molecular underpinnings of the observed effects are discussed. It is concluded that the effects in question are of relevance for drug performance and need to be taken into account in preformulation studies.

Investigation of miscibility estimation methods between indomethacin and poly(vinylpyrrolidone-co-vinyl acetate)

The investigation of the miscibility between active pharmaceutical ingredients (API's) and polymeric excipients is of great interest for the formulation and development of amorphous solid dispersions, especially in the context of the prediction of the stability of these systems. Two different methods were applied to determine the miscibility between model compounds poly(vinylpyrrolidone-co-vinyl acetate) (PVPVA) and indomethacin (IND), viz. the measurement of the glass transition temperature (T_g) and the melting point depression method framed on the Flory-Huggins theory. Measurement of the glass transition temperatures of the binary blends showed the formation of an amorphous single phase system between the PVPVA and the IND regardless of the composition. Variation of T_g with the composition was well described by the Gordon-Taylor equation leading to the error of concluding lack of intermolecular interactions between the materials. Application of the Brostow-Chiu-Kalogeras-Vassilikou-Dova (BCKV) model shows a negative interaction parameter (a₀) suggesting the presence of drug-drug intermolecular interactions. Application of the melting point depression method within the framework of the Flory-Huggins theory proved the miscibility of the system at temperatures close to the melting point of IND.