Vinylpyrrolidone-vinyl Acetate Research Articles

Colyophilized Sugar-Polymer Dispersions for Enhanced Processing and Storage Stability.

Sucrose and trehalose pharmaceutical excipients are employed to stabilize protein therapeutics in a dried state. The mechanism of therapeutic protein stabilization is dependent on the sugars being present in an amorphous solid-state. Colyophilization of sugars with high glass transition polymers, polyvinylpyrrolidone (PVP), and poly(vinylpyrrolidone vinyl acetate) (PVPVA), enhances amorphous sugar stability. This study investigates the stability of colyophilized sugar-polymer systems in the frozen solution state, dried state postlyophilization, and upon exposure to elevated humidity. Binary systems of sucrose or trehalose with PVP or PVPVA were lyophilized with sugar/polymer ratios ranging from 2:8 to 8:2. Frozen sugar-PVPVA solutions exhibited a higher glass transition temperature of the maximally freeze-concentrated amorphous phase (Tg') compared to sugar-PVP solutions, despite the glass transition temperature (Tg) of PVPVA being lower than PVP. Tg values of all colyophilized systems were in a similar temperature range irrespective of polymer type. Greater hydrogen bonding between sugars and PVP and the lower hygroscopicity of PVPVA influenced polymer antiplasticization effects and the plasticization effects of residual water. Plasticization due to water sorption was investigated in a dynamic vapor sorption humidity ramping experiment. Lyophilized sucrose systems exhibited increased amorphous stability compared to trehalose upon exposure to the humidity. Recrystallization of trehalose was observed and stabilized by polymer addition. Lower concentrations of PVP inhibited trehalose recrystallization compared to PVPVA. These stabilizing effects were attributed to the increased hydrogen bonding between trehalose and PVP compared to trehalose and PVPVA. Overall, the study demonstrated how differences in polymer hygroscopicity and hydrogen bonding with sugars influence the stability of colyophilized amorphous dispersions. These insights into excipient solid-state stability are relevant to the development of stabilized biopharmaceutical solid-state formulations.

Implications of Low-concentration Polymer on the Physical Stability of Glassy Griseofulvin: Role of the Segmental Mobility.

Crystallization of amorphous pharmaceutical solids are widely reported to be affected by the addition of polymer, while the underlying mechanism require deep study. Herein, crystal growth behaviors of glassy griseofulvin (GSF) doped with various 1% w/w polymer were systematically studied. From the molecular structure, GSF cannot form the hydrogen bonding interactions with the selected polymer poly(vinyl acetate), polyvinyl pyrrolidone (PVP), 60:40 vinyl pyrrolidone-vinyl acetate copolymer (PVP/VA 64), and poly(ethylene oxide) (PEO). 1% w/w polymer exhibited weak or no detectable effects on the glass transition temperature (Tg) of GSF. However, crystal growth rates of GSF was altered from 4.27-fold increase to 2.57-fold decrease at 8 ℃ below Tg of GSF. Interestingly, the ability to accelerate and inhibit the growth rates of GSF crystals correlated well with Tg of polymer, indicating the controlling role of segmental mobility of polymer. Moreover, ring-banded growth of GSF was observed in the polymer-doped systems. Normal compact bulk and ring-banded crystals of GSF were both characterized as the thermodynamically stable form I. More importantly, formation of ring-banded crystals of GSF can significantly weaken the inhibitory effects of polymer on the crystallization of glassy GSF.

3D Printing of Personalised Carvedilol Tablets Using Selective Laser Sintering.

Selective laser sintering (SLS) has drawn attention for the fabrication of three-dimensional oral dosage forms due to the plurality of drug formulations that can be processed. The aim of this work was to employ SLS with a CO2 laser for the manufacturing of carvedilol personalised dosage forms of various strengths. Carvedilol (CVD) and vinylpyrrolidone-vinyl acetate copolymer (Kollidon VA64) blends of various ratios were sintered to produce CVD tablets of 3.125, 6.25, and 12.5 mg. The tuning of the SLS processing laser intensity parameter improved printability and impacted the tablet hardness, friability, CVD dissolution rate, and the total amount of drug released. Physicochemical characterization showed the presence of CVD in the amorphous state. X-ray micro-CT analysis demonstrated that the applied CO2 intensity affected the total tablet porosity, which was reduced with increased laser intensity. The study demonstrated that SLS is a suitable technology for the development of personalised medicines that meet the required specifications and patient needs.

Development of printable inks for 3D printing of personalized dosage forms: Coupling of fused deposition modelling and jet dispensing

3D printing technologies have gained significant attention for the development of personalized pharmaceutical dosage forms. Here we present the coupling of Fused Deposition Modelling (FDM) and jet dispensing for the printing of polyvinyl alcohol (PVA) tablets followed by dispensing of rosuvastatin calcium (RSV) – polymer inks for customization of the drug dissolution rates. By using the drop on demand approach, methacrylate (EUDRAGIT EPO), vinylpyrrolidone-vinyl acetate copolymer (Kollidon VA64), and ethylcellulose (Aqualon) inks loaded with RSV were dispensed in FDM printed tablets, bearing 5 and 15 mg of active dose respectively. Physicochemical characterization revealed that RSV was molecularly dispersed in the deposited inks. Various dissolution rates were obtained based on the polymer solubility in the dissolution media and the drug loading. The study is a paradigm of printing personalized dosage forms through the development of suitable inks.

Inhibition of Liquid-Liquid Phase Separation for Breaking the Solubility Barrier of Amorphous Solid Dispersions to Improve Oral Absorption of Naftopidil.

Amorphous solid dispersion (ASD) is one of the most promising technologies for improving the oral absorption of poorly soluble compounds. In this study, naftopidil (NFT) ASDs were prepared using vinylpyrrolidone-vinyl acetate copolymer (PVPVA), hydroxypropyl methylcellulose acetate succinate (HPMCAS), and poly(methacrylic acid-co-methyl methacrylate) L100-55 (Eudragit) to improve the dissolution and oral absorption behaviors of NFT. During the dissolution process of ASD, liquid-liquid phase separation (LLPS) may occur when certain requirements are met for providing a maximum quasi-stable concentration achievable by amorphization. The occurrence of LLPS was confirmed in the presence of PVPVA and HPMCAS; however, Eudragit inhibited LLPS owing to its molecular interaction with NFT. Although the dissolution behavior of the Eudragit ASD was found to be markedly poorer than that of other ASDs, it offered the best oral absorption in rats. The findings of the current study highlight the possibility for improving the oral absorption of poorly soluble drugs by this ASD, which should be eliminated from candidate formulations based on the conventional in vitro tests.

Artificial neural networks and their application in the optimization of carbamazepine solid dispersions

The aim of this study was to examine the possibility of using artificial neural networks in the optimization of solid dispersions with carbamazepine. Artificial neural networks of the Generalized regression neural network type with four layers, gave models that describe the effect of components in solid dispersions carbamazepine-Neusilin ® UFL2 (magnesium aluminosilicate)-Collidon ® VA64 (vinylpyrrolidone-vinyl acetate) and dissolved carbamazepine value (%) after 10 (Q10) and 30(Q30) minutes of carbamazepine testing. After the learning process, root mean square error (RMS) values of 0.0029 were obtained for the training data set, and 0.1185 for the test training data, which is an excellent prediction of the neural network.

Rivaroxaban lyospheres prepared by a dimethyl sulfoxide-based spray-freeze-drying process

Spray-freeze-drying (SFD) processes are usually using aqueous solvent systems, which however, exclude the use of SFD for poorly water-soluble drugs/excipients. Here, we evaluated dimethyl sulfoxide for its suitability in formulating SFD particles (lyospheres®). Rivaroxaban was spray-freeze-dried from DMSO solutions containing polyvinyl pyrrolidone (PVP; Kollidon® 25), vinylpyrrolidone-vinyl acetate copolymer (PVP-VA; Kollidon® VA64) or polyvinyl alcohol 4–88 (PVA) forming porous lyospheres® (median particle size 250 to 350 µm). Rivaroxaban was amorphous with all three polymers, which in combination with the high porosity resulted in rapid dissolution in vitro within 10 min. Consequently, this translated in lower Tmax (0.5–1.0 h) after oral administration of lyospheres® to rats (compared with Tmax of 4 h with coarse rivaroxaban). Lyosphere formulations achieved a distinct bioavailability increase (AUC(0-inf) = 1487 ± 657 ng*h/ml with PVP; 4426 ± 1553 ng*h/ml with PVP-VA; 9569 ± 3868 ng*h/ml with PVA lyospheres®; whereas 385 ± 145 ng*h/ml with coarse rivaroxaban). These in vitro and in vivo results underlined the benefit of using DMSO in SFD that can broaden the applicability of the SFD process to a much larger repertoire of poorly water-soluble drugs/excipients.

Dose-independent drug release from 3D printed oral medicines for patient-specific dosing to improve therapy safety

Fused deposition modelling (FDM) 3D printing provides the ability to address individual patients’ therapeutic needs without having to change the formulation every time. This is particularly interesting for dosing and release modelling. In this study, a geometry model was developed that can represent variable dosages while keeping the surface area to volume (SA/V) ratio alike, so the drug release profiles remain similar. The model was tested on three different formulations. Two BCS I active pharmaceutical ingredients (API), pramipexole and levodopa, and one BCS II API, praziquantel, were used. Polyvinyl alcohol (PVA, water soluble) and a combination of vinylpyrrolidone-vinyl acetate copolymer (PVP-VA, water soluble) and ethylene–vinyl acetate (EVA, water insoluble) were used as the polymer matrix. The curves were compared using the similarity factor (f2 value) and mean dissolution time (MDT). Using a hollow cylinder-based (HCb) geometry model, a dose-independent drug release could be realized. For the PVA formulations, an 8-fold dose change could be obtained and for the EVA-PVP-VA formulation a factor of 5.5 could be achieved, with f2 > 50. Due to the layer structure of the printed objects, very fine dose variation of 0.13 mg per layer is possible within these models. This allows variable dosing in small steps with only one basis formulation.

Revealing the roles of polymers in supersaturation stabilization from the perspective of crystallization behaviors: A case of nimodipine

Formulating drugs into amorphous solid dispersions (ASDs) represents an attractive means to enhance the aqueous solubility of drugs. Furthermore, water-soluble polymers have proven highly advantageous for stabilizing supersaturated solutions of ASDs. However, the performance and mechanism of various polymers in stabilizing supersaturated drug solutions have not been well-studied. The aim of this study was to investigate the effects of different commercial polymers on the dissolution behaviors and supersaturation stabilization of the ASDs and to further explore the mechanism of polymer mediated supersaturation maintenance by studying the crystallization behaviors of the ASDs. In this study, nimodipine (NMD) was used as a model drug because of its poor water-solubility and fast crystallization rate in aqueous solution, and three polymers polyvinylpyrrolidone (PVP), vinylpyrrolidone-vinyl acetate copolymer (PVP VA), and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft co-polymer (Soluplus) was selected as the drug carriers to form the ASDs with NMD. Solid-state characterizations of the ASDs confirmed the amorphous state of the ASD systems. ASDPVP VA demonstrated superior supersaturation maintenance in dissolution experiments compared to the other two ASD systems. Among the polymers tested, PVP VA most efficiently maintained dissolution of NMD and prevented its crystallization from the supersaturated solution. The ability of PVP VA to most-effectively maintain supersaturation of the drug was manifested by inhibition of crystal nucleation rather than inhibition of crystal growth following nucleation. These results suggest that nucleation inhibition was instrumental in enabling the polymer-mediated supersaturation maintenance, at least with NMD.

Ball milling and hot-melt extrusion of indomethacin–l-arginine–vinylpyrrolidone-vinyl acetate copolymer: Solid-state properties and dissolution performance

Commonly applied approaches to enhance the dissolution properties of low water-soluble crystalline active pharmaceutical ingredients (APIs) include their amorphization by incorporation into a polymeric matrix and the formation of amorphous solid dispersions, or blending APIs with low-molecular-weight excipients and the formation of a co-amorphous system. This study focused on the preparation and characterization of binary (consisting of indomethacin (IND) and polymer – copovidone (PVP VA 64), as a carrier, or amino acid – L-arginine (ARG), as a co-former) and ternary (comprising the same API, polymer, and amino acid) formulations. Formulations were produced by ball milling (BM) and/or hot-melt extrusion (HME), and extensive physicochemical characterization was performed. Specifically, the physicochemical and solid-state properties of a model IND–ARG system incorporated into a polymeric matrix of PVP VA 64 by HME and BM as well as by combined BM/HME method together with the impact of the preparation strategy on the dissolution profiles and long-term physical stability were investigated. Ball-milled binary and ternary formulations were found to be amorphous. The residual crystals corresponding to IND–ARG salt were identified in the ternary formulations produced via HME. Despite the presence of a crystalline phase, dissolution tests showed that ternary systems prepared by HME exhibited improved IND solubility when compared to pure crystalline IND and their corresponding physical mixture. None of the binary and ternary formulations that were initially fully amorphous did undergo recrystallization during the entire period of preservation (minimum of 12 months) in dry conditions at 25 °C.

Selective Laser Sintering of a Photosensitive Drug: Impact of Processing and Formulation Parameters on Degradation, Solid State, and Quality of 3D-Printed Dosage Forms.

This research study utilized a light-sensitive drug, nifedipine (NFD), to understand the impact of processing parameters and formulation composition on drug degradation, crystallinity, and quality attributes (dimensions, hardness, disintegration time) of selective laser sintering (SLS)-based three-dimensional (3D)-printed dosage forms. Visible lasers with a wavelength around 455 nm are one of the laser sources used for selective laser sintering (SLS) processes, and some drugs such as nifedipine tend to absorb radiation at varying intensities around this wavelength. This phenomenon may lead to chemical degradation and solid-state transformation, which was assessed for nifedipine in formulations with varying amounts of vinyl pyrrolidone-vinyl acetate copolymer (Kollidon VA 64) and potassium aluminum silicate-based pearlescent pigment (Candurin) processed under different SLS conditions in the presented work. After preliminary screening, Candurin, surface temperature (ST), and laser speed (LS) were identified as the significant independent variables. Further, using the identified independent variables, a 17-run, randomized, Box-Behnken design was developed to understand the correlation trends and quantify the impact on degradation (%), crystallinity, and quality attributes (dimensions, hardness, disintegration time) employing qualitative and quantitative analytical tools. The design of experiments (DoEs) and statistical analysis observed that LS and Candurin (wt %) had a strong negative correlation on drug degradation, hardness, and weight, whereas ST had a strong positive correlation with drug degradation, amorphous conversion, and hardness of the 3D-printed dosage form. From this study, it can be concluded that formulation and processing parameters have a critical impact on stability and performance; hence, these parameters should be evaluated and optimized before exposing light-sensitive drugs to the SLS processes.

Engineered Hydrophobin as a Crystallization Inhibitor for Flufenamic Acid.

Hydrophobins are multifunctional, highly surface-active proteins produced in filamentous fungi. Due to their surface-active properties, resistance to degradation, and potential immunological inertness, hydrophobins have been used in many applications such as protein purification, increasing implant biocompatibility, increasing water solubility of insoluble drugs, and foam stabilizers for food products. To further explore surface-active and self-assembly properties of hydrophobins, we evaluated an engineered, recombinant hydrophobin (class II type 1, HFB1) as a potential crystallization inhibitor for maintaining drug supersaturation for an amorphous drug delivery system. A supersaturation-precipitation method was employed utilizing an ultraviolet (UV) fiber optic system for tracking precipitation kinetics of a model drug, flufenamic acid (FA), that was selected due to its low aqueous solubility in its crystalline form. The effectiveness of HFB1 as a crystallization inhibitor was compared with commonly used pharmaceutical grade polymeric crystallization inhibitors. The following polymers were selected to compare with HFB1: methocel (A4C grade), methocel (K15M grade), Kollidon vinylpyrrolidone-vinyl acetate (VA64), and hydroxypropyl methylcellulose acetate succinate (HPMCAS) (MF grade). The supersaturation-precipitation experiments concluded that HFB1 outperformed all polymers tested in this study and can potentially be used as a crystallization inhibitor at significantly lower concentrations in amorphous drug delivery systems. Dynamic light scattering (DLS) and circular dichroism (CD) results suggest a crystallization inhibition mechanism in which HFB1 functions differently depending on whether flufenamic acid is molecularly dispersed but supersaturated relative to its crystalline solubility or it has exceeded its amorphous solubility limit and exists as a phase-separated drug-rich colloid.

Miscibility and thermal properties of poly(vinylpyrrolidone-vinyl acetate)/lamivudine and tenofovir binary blends prepared by hot melt extrusion

Preparation of amorphous solid dispersions (ASD) by hot melt extrusion (HME) of poly(vinylpyrrolidone-vinyl acetate) (Kollidon) and the active pharmaceutical ingredients (API) Lamivudine (3TC) and Tenofovir Disoproxyl Fumarate (TDF) was investigated aiming to study their miscibility and thermal behavior. These two drugs are currently used as drugs in first line treatment of patients with Acquired Immunodeficiency Syndrome (AIDS). In order to predetermine parameters for extrusion and the maximum concentration of API to be used without any recrystallization, binary blends were first processed in the mixing chamber at 130°C using a roller type rotor at 10, 20 and 30 rpm for 7 min, giving rise to ASD of both API, at least up to 20 wt% of the drug. Both 3TC and TDF were then extruded individually with Kollidon in a single screw extruder. HME produced ASD with high concentration of both Kollidon/API combinations, being part of the API soluble in the polymer matrix. From HME, Kollidon/3TC forms ASD in concentration up to 50 wt%, but from 30 wt% 3TC, the ASD has no time stability, showing recrystallization in less than 5 months, while the Kollidon/TDF system forms ASD up to 30 wt% of TDF, but it has aging stability inferior to 4 months.

Novel Extraction Method Using Excipients to Enhance Yield of Genistein and Daidzein in Trifolium pratensis L.

Isoflavones can be found in different chemical forms, but the health beneficial effects mainly appear in their free forms—aglycones. Their yield in red clover (Trifolium pratensis L.) extracts differs due to different extraction and hydrolysis methodologies. The main aim of this study was to obtain the highest yields of daidzein and genistein from red clover blossoms through the various extraction and hydrolysis methods and to increase their quantities using additional excipients. Extracts were obtained by ultrasound-assisted, heat-reflux and maceration methods combining them with acidic, alkaline, and thermal hydrolysis. Using ultrasound-assisted extraction with optimal conditions and heat-reflux method highest yields of isoflavones were obtained in UTE510 (393.23 ± 19.66 µg/g daidzein and 171.57 ± 8.58 µg/g genistein); UTE530 (415.07 ± 20.75 µg/g daidzein and 150.57 ± 7.53 µg/g genistein) and HNE5 (432.30 ± 21.61 µg/g daidzein and 154.50 ± 7.72 µg/g genistein) samples. These conditions were used with excipients: magnesium aluminometasilicate, croscarmellose sodium, sodium carboxymethyl starch and vinylpyrrolidone-vinyl acetate copolymer. This is the first study reporting the ability of the vinylpyrrolidone-vinyl acetate copolymer to promote solubilization and availability of active compounds from a herbal extract, resulting in enhanced isoflavones yield. The results of the present study showing increased solubility and availability provided by the vinylpyrrolidone-vinyl acetate copolymer suggest that this preparation could in principle also reduce variability due to limited water solubility of isoflavones.

Stabilizing effect of the cyclodextrins additive to spray-dried particles of curcumin/polyvinylpyrrolidone on the supersaturated state of curcumin

Although curcumin is considered to have various therapeutic effects, its use as a functional food or supplement is restricted owing to its low water solubility and bioavailability. To increase the solubility of curcumin in water, the use of polyvinylpyrrolidone (PVP) and vinylpyrrolidone-vinyl acetate copolymers with a pyrrolidone skeleton was noted to be promising. In particular, the bi-component formulations of curcumin/PVP prepared through spray drying exhibited an amorphous state in powder X-ray diffraction observations and temporally increased the apparent solubility of curcumin to over 5000 times that of untreated curcumin; nevertheless, after 24 h, the solubility decreased owing to the unstable supersaturated state of curcumin. The addition of α-cyclodextrin (α-CyD) in the bi-component curcumin/PVP formulation helped maintain the supersaturated state of curcumin, whereas the addition of β- and γ-CyD led to the collapse of the supersaturated state. The addition of α-CyD can likely help inhibit the nucleation and crystal growth of curcumin, through the interaction among the solubilized units of curcumin/PVP and α-CyD.

Relevance of Liquid-Liquid Phase Separation of Supersaturated Solution in Oral Absorption of Albendazole from Amorphous Solid Dispersions.

Amorphous solid dispersion (ASD) is one of the most promising formulation technologies for improving the oral absorption of poorly soluble drugs, where the maintenance of supersaturation plays a key role in enhancing the absorption process. However, quantitative prediction of oral absorption from ASDs is still difficult. Supersaturated solutions can cause liquid-liquid phase separation through the spinodal decomposition mechanism, which must be adequately comprehended to understand the oral absorption of drugs quantitatively. In this study, albendazole (ALZ) was formulated into ASDs using three types of polymers, poly(methacrylic acid-co-methyl methacrylate) (Eudragit) L100, Vinylpyrrolidone-vinyl acetate copolymer (PVPVA), and hydroxypropyl methylcellulose acetate succinate (HPMCAS). The oral absorption of ALZ in rats administered as ASD suspensions was not explained by dissolution study but was predicted using liquid-liquid phase separation concentration, which suggested that the absorption of ALZ was solubility-limited. The oral administration study in dogs performed using solid capsules demonstrated the low efficacy of ASDs because the absorption was likely to be limited by dissolution rate, which indicated the importance of designing the final dosage form of the ASDs.

Development of immediate release (IR) 3D-printed oral dosage forms with focus on industrial relevance

Pharmaceutical 3D-printing represents a potentially new dosing and manufacturing approach for the pharmaceutical industry, with unique opportunities for personalization of dosage strengths. Fused deposition modelling (FDM) is a 3D-printing technique, which presents advantages for decentralized on-site manufacturing in hospitals and pharmacies. This study introduces industrially relevant development of formulations for filaments with the required mechanical properties to be 3D-printable and providing immediate release (IR) dosage forms using safe materials approved also for pediatric use. Hydroxypropyl-cellulose (HPC) SSL was chosen as hydrophilic polymer and caffeine with a load of 5-20% as thermally stable model drug. Poly-(vinyl pyrrolidone-vinyl acetate) copolymer (Kollidon VA64) and poly-(vinyl alcohol-polyethylene glycol) graft copolymer (Kollicoat IR) were additional water-soluble polymers tested in combination with HPC and xylitol and polyethylene glycol (PEG) 4000 were evaluated as hydrophilic plasticizers and PEG4000 and maltodextrin as pore formers. Formulations were hot-melt extruded using a scalable twin-screw extruder and 3D-printed into honeycomb geometry solid dosage forms with high (100%) and low (80%) infill density. Rapid or very rapid release was achieved via formulation selection and tablet design parameters. PEG4000 in combination with Kollidon VA64 demonstrated superior processability and significantly accelerated release properties of the matrix independently of infill density. Lowering caffeine content improved hot-melt extrusion processability for each formulation but prolonged dissolution. The use of Kollicoat IR resulted in superior mechanical properties of the manufactured filaments, with easy handling and successful 3D-printing for drug load of 5 to 20%. For most formulations, lowering infill density of 3D-printed tablets yielded faster drug dissolution in agreement with the literature. However, the extent of the infill density effect varied depending on formulation. Caffeine was present in stable crystalline state in 3D-printed tablets. Printing temperature appeared to be critical for drug dissolution in vitro. This wide-ranging excipient investigation epitomizes the beginning of a toolbox approach targeting FDM processability in combination with immediate release characteristics of personalized dosage forms.

Mechanodegradation of Polymers: A Limiting Factor of Mechanochemical Activation in the Production of Amorphous Solid Dispersions by Cryomilling.

In this study, we report on the influence of mechanochemical activation on the chemical stability of amorphous solid dispersions made up of indomethacin and hydroxypropyl methyl cellulose (HPMC), poly(vinylpyrrolidone) (PVP), poly(vinylpyrrolidone vinylacetate) (PVPVA), or Soluplus. In agreement with our recently published work, all applied carriers were found to be prone to polymer degradation. Covalent bonds within the polymers were cleaved and mechanoradicals were generated. Furthermore, decomposition of indomethacin was also observed but occurred only in the presence of polymers. Hence, it is proposed that the generated mechanoradicals from the polymers are responsible for the chemical degradation of indomethacin. Our study also strongly suggests the existence of a critical polymer- and process-dependent molecular weight limit "M∞", below which only limited mechanodegradation takes place since the lower-molecular-weight polymer PVP K12PF had a less profound influence on the degradation of indomethacin in comparison to PVP K25.

Evaluating supersaturation in vitro and predicting its performance in vivo with Biphasic gastrointestinal Simulator: A case study of a BCS IIB drug.

This study aimed to develop an evaluation approach for supersaturation by employing an in vitro bio-mimicking apparatus designed to predict in vivo performance. The Biphasic Gastrointestinal Simulator (BGIS) is composed of three chambers with absorption phases that represent the stomach, duodenum, and jejunum, respectively. The concentration of apatinib in each chamber was detected by fiber optical probes in situ. The dissolution data and the pharmacokinetic data were correlated by GastroplusTM. The precipitates were characterized by polarizing microscope, Scanning Electron Microscopy, Powder X-ray diffraction and Differential scanning calorimetry. According to the results, Vinylpyrrolidone-vinyl acetate copolymer (CoPVP) prolonged supersaturation by improving solubility and inhibiting crystallization, while Hydroxypropyl methylcellulose (HPMC) prolonged supersaturation by inhibiting crystallization alone. Furthermore, a predictive in vitro-in vivo correlation was established, which confirmed the anti-precipitation effect of CoPVP and HPMC on in vitro performance and in vivo behavior. In conclusion, CoPVP and HPMC increased and prolonged the supersaturation of apatinib, and then improved its bioavailability. Moreover, BGIS was demonstrated to be a significant approach for simulating in vivo conditions for in vitro-in vivo correlation in a supersaturation study. This study presents a promising approach for evaluating supersaturation, screening precipitation inhibitors in vitro, and predicting their performances in vivo.

Impact of degree of supersaturation on the dissolution and oral absorption behaviors of griseofulvin amorphous solid dispersions

Although amorphous solid dispersion (ASD) is widely recognized as a formulation technology to improve oral absorption of poorly soluble drugs, prediction of its oral absorption behavior from in vitro dissolution tests is still difficult. This becomes especially challenging for drugs with high crystallization tendency, because crystallization during dissolution tests and in the gastrointestinal tract makes dissolution and precipitation behaviors complex. In this study, attempts were made to explain the oral absorption behavior of griseofulvin (GF), a drug with high crystallization tendency, from ASDs using in vitro supersaturation and dissolution tests with a focus on the effect of the degree of supersaturation. Liquid-liquid phase separation of a supersaturated GF solution in the presence of vinylpyrrolidone-vinyl acetate copolymer (PVPVA), Eudragit (Poly(methacrylic acid-co-methyl methacrylate)) L100-55 (Eudragit), or hydroxypropyl methylcellulose acetate succinate (HPMCAS) was investigated based on turbidity measurements to find that the apparent phase separation concentration was increased in the presence of all polymers. In both the dissolution test and oral absorption study, a significant effect of the degree of supersaturation was observed presumably because of high crystallization tendency of GF. Thus, dose setting in the dissolution test was important to achieve an in vitro-in vivo correlation of GF ASDs. Other conditions required for the in vivo predictive dissolution study included pH-shift and surfactant addition. The apparent liquid-liquid phase separation concentration also worked as a rough predictor of the oral absorption of GF from ASD.