Inhomogeneous Phase Significantly Reduces Oral Bioavailability of Felodipine/PVPVA Amorphous Solid Dispersion.

Inhomogeneity is a key factor that significantly influences the dissolution behavior of amorphous solid dispersion (ASD). However, the underlying mechanisms of the effects of inhomogeneous phase on the dissolution characteristics as well as the bioavailability of ASDs are still unclear. In this study, two types of felodipine/PVPVA based ASDs with 30 wt % drug loading but different homogeneity were prepared: homogeneous "30 wt % ASD" prepared by spray drying, as well as inhomogeneous "30 wt % PM" prepared by physically mixing the sprayed dried 70 wt % ASD with PVPVA. We aimed to investigate (1) drug-polymer interaction mechanism and "apparent" interaction strength within the two ASDs and (2) dissolution mechanism as well as in vivo performance of the two ASDs. DSC thermogram revealing a single Tg in 30 wt % ASD confirmed its homogeneous phase. 1H NMR, FT-IR, and DVS studies collectively proved that strong hydrogen bonding interactions formed between felodipine and PVPVA in ASDs. Moreover, homogeneous "30 wt % ASD" has more numbers of interacting drug-polymer pairs, and thus exhibits stronger "apparent" interaction strength comparing with that of inhomogeneous "30 wt % PM". Unexpectedly,in the in vitro dissolution studies, inhomogeneous "30 wt % PM" showed much faster dissolution and also generated drug concentration ∼4.4 times higher than that of homogeneous "30 wt % ASD". However, drug precipitate recrystallized much slower in homogeneous "30 wt % ASD", presumably because much more polymer coprecipitated with amorphous drug in this system, which helps inhibiting drug crystallization. Surprisingly, homogeneous "30 wt % ASD" showed a significantly higher bioavailability in the in vivo pharmacokinetic studies, with the maximum plasma concentrations (Cmax) and the area under the curve (AUC) values of about 2.7 and 2.3 times higher than those of inhomogeneous "30 wt % PM". The above findings indicated that the amorphous state of drug precipitate contributes significantly to increase bioavailability of ASDs, while traditional in vitro dissolution studies, for instance, if we only compare the dissolved drug in solution or the capability of an ASD to generate supersaturation, are inadequate to predict in vivo performance of ASDs. In conclusion, the phase behavior of ASDs directly impact the formation of drug-polymer interaction, which controls not only drug supersaturation in solution but also drug crystallization in precipitate, and ultimately affect the in vivo performance of ASDs.

L-Type Ca2+ Channel Inhibition Rescues the LPS-Induced Neuroinflammatory Response and Impairments in Spatial Memory and Dendritic Spine Formation.

Ca2+ signaling is implicated in the transition between microglial surveillance and activation. Several L-type Ca2+ channel blockers (CCBs) have been shown to ameliorate neuroinflammation by modulating microglial activity. In this study, we examined the effects of the L-type CCB felodipine on LPS-mediated proinflammatory responses. We found that felodipine treatment significantly diminished LPS-evoked proinflammatory cytokine levels in BV2 microglial cells in an L-type Ca2+ channel-dependent manner. In addition, felodipine leads to the inhibition of TLR4/AKT/STAT3 signaling in BV2 microglial cells. We further examined the effects of felodipine on LPS-stimulated neuroinflammation in vivo and found that daily administration (3 or 7 days, i.p.) significantly reduced LPS-mediated gliosis and COX-2 and IL-1ß levels in C57BL/6 (wild-type) mice. Moreover, felodipine administration significantly reduced chronic neuroinflammation-induced spatial memory impairment, dendritic spine number, and microgliosis in C57BL/6 mice. Taken together, our results suggest that the L-type CCB felodipine could be repurposed for the treatment of neuroinflammation/cognitive function-associated diseases.

"Novel mucoadhesive PLGA-PVM/MA micro-nanocomposites loaded with felodipine intended for pulmonary administration by nebulization".

Poly(latic-co-glycolic) acid (PLGA) nanoparticles loaded with felodipine (FEL) were embedded in a mucoadhesive matrix of poly (methyl vinyl ether-co-maleic anhydride) (PVM/MA) to prepare micro-nanoparticulate composites by particle engineering. Composites were characterized for physical and rheological properties and formulated with inhalable grade lactose. In-vitro characterization studies such as drug release kinetics, and mucoadhesive, and aerodynamic properties were performed. The in-vivo efficacy was evaluated by administering the optimized composites by nebulization in hypertensive rats. The obtained FEL-PLGA-PVM/MA composites of 1,069 ± 82 nm showed sustained drug release and mucoadhesive properties. Bulk and tapped densities of composites mixed with lactose were 0.08-0.13 g/mL and 0.18-0.30 g/mL, respectively, with mass median aerodynamic diameters (MMAD) in a range of 1.29-12.0 µm. After pulmonary administration of the composites, a decrease in systolic and diastolic blood pressure was observed within the first 3 h, of -9.0 ± 1.3 % and -13.9 ± 3.3 %, respectively, with a maximal effect at 12 h (sustained during 144 h), in contrast to pure FEL, which showed no significant decrease in blood pressure (1.6 ± 2.7 % and 4.1 ± 4.1 %). Findings suggest that novel mucoadhesive FEL-PLGA-PVM/MA composites are a promising strategy formulation to treat systemic diseases by pulmonary route.

Influence of the crystallization tendencies of pharmaceutical glasses on the applicability of the Adam-Gibbs-Vogel and Vogel-Tammann-Fulcher equations in the prediction of their long-term physical stability.

Amorphization is a powerful approach for improving the aqueous solubility and bioavailability of poorly water-soluble compounds. However, it can cause chemical and physical instability, the latter of which can lead to crystallization during storage, diminishing the solubility advantage of the amorphous state. As there is no standard method for predicting the physical stability of amorphous materials, a long-term stability study is needed in drug development. This study investigated the correlation between the physical stability of amorphous compounds and molecular mobility based on the assumption that physical stability is governed by the diffusional motion of a molecule. Model compounds were evaluated for crystallization onset time, structural relaxation time, fragility, and fictive temperature. The crystallization onset time of acetaminophen glass correlated with its relaxation time calculated from the Adam-Gibbs-Vogel equation; however, that of felodipine glass correlated with the relaxation time calculated from the Vogel-Tammann-Fulcher equation. The different crystallization tendencies of these compounds can be explained by the differences in the rate limiting steps in their crystallization processes, indicating the importance of distinguishing the critical process associated with crystallization. These findings will be useful for more accurate prediction of long-term physical stability of amorphous materials.

Efficacy of felodipine and enalapril in the treatment of essential hypertension with coronary artery disease and the effect on levels of Salusin-ß, Apelin, and PON1 gene expression in patients.

This study aimed to analyze the effect of felodipine combined with enalapril in the treatment of patients with essential hypertension and coronary artery disease. Also, the effect of these medicines was evaluated on the peripheral blood Salusin-ß, Apelin levels, and PON1 gene expression. For this purpose, 110 patients with essential hypertension combined with coronary heart disease, admitted to the hospital from January 2019 to January 2021, were selected and randomly divided into two groups. The control group was given felodipine treatment alone, and the study group was treated with combined application of felodipine and enalapril. The treatment effect, peripheral blood Salusin-ß, Apelin, PON1 gene expression, and the safety of medication were compared between the two groups. The results showed that the post-treatment systolic blood pressure in the study group was 119.77 ± 5.23 mm Hg and diastolic blood pressure was 86.84 ± 5.42 mm Hg, both of which were significantly lower than those in the control group (127.81 ± 6.92 mm Hg and 95.13 ± 6.08 mm Hg), with statistically significant differences (p<0.05). The effective rates of the study group and the control group were 92.73% and 74.54% respectively, with statistically significant differences (P<0.05). The post-treatment peripheral blood Salusin-ßlevel in the study group was 3.77±0.53mmol/L, and Apelin was 1.94±0.58µg/L, with statistically significant differences compared to the control group (P<0.05). The PON1 gene expression in the study group was higher than those in the control group after treatment (P<0.05). Also, the results showed that there was no statistical difference in adverse reactions between the two groups (P>0.05). According to these results, the combination of felodipine and enalapril in patients with essential hypertension combined with coronary artery disease can effectively lower the patients' blood pressure and improve their peripheral blood Salusin-ß, Apelin levels, and PON1 gene expression, thus enhancing the patients' therapeutic effect with few adverse effects and high safety.

Effect of repeated Shengmai-San administration on nifedipine pharmacokinetics and the risk/benefit under co-treatment.

Herbal interactions with nifedipine/felodipine through cytochrome P450 (CYP) 3A inhibition is significant in humans. Shengmai-San (SMS), a three-herbal formula of Chinese medicine, is commonly prescribed in Asia populations for cardiovascular disorders. This study aimed to elucidate the impact of SMS on nifedipine/felodipine treatment by the findings from rat pharmacokinetic study of nifedipine to the retrospective cohort study of patients with hypertension. The 3-week SMS treatment increased the systemic exposure to nifedipine by nearly two-fold and decreased nifedipine clearance by 39% in rats. Among the ingredients of SMS component herbs, schisandrin B, schisantherin A, and methylophiopogonanone A, inhibited the nifedipine oxidation (NFO) activities of rat hepatic and intestinal microsomes, as well as human CYP3A4. Methylophiopogonanone A was identified as a time-dependent inhibitor of CYP3A4. After 1:5 propensity score matching, 4,894 patients with nifedipine/felodipine use were analyzed. In patients receiving nifedipine/felodipine, the subgroup with concurrent SMS treatment had a higher incidence of headache (92.70 per 1,000 personyears) than the subgroup without SMS treatment (51.10 per 1,000 person-years). There was a positive association between headache incidence and cumulative doses of SMS (1-60 g SMS: hazard ratio (HR): 1.39; 95% confidence interval (CI): 1.11-1.74; >60 g SMS: HR: 1.97; 95% CI: 1.62-2.39; p < 0.0001). However, patients who had higher cumulative SMS doses had a lower risk of all-cause mortality (1-60 g SMS: HR: 0.67; 95% CI: 0.47-0.94; >60 g SMS: HR: 0.54; 95% CI: 0.37-0.79; p = 0.001). Results demonstrated increased rat plasma nifedipine levels after 3-week SMS treatment and increased headache incidence should be noted in nifedipine/felodipine-treated patients with prolonged SMS administration.

Water-Resistant Drug-Polymer Interaction Contributes to the Formation of Nano-Species during the Dissolution of Felodipine Amorphous Solid Dispersions.

Drug-polymer interactions are of great importance in amorphous solid dispersion (ASD) formulation for both dissolution performance and physical stability considerations. In this work, three felodipine ASD systems with drug loading ranging from 5 to 20% were prepared using PVP, PVP-VA, or HPMC-AS as the polymer matrix. The amorphization and homogeneity were confirmed by differential scanning calorimetry and powder X-ray diffraction. The intrinsic dissolution behavior of these ASDs was studied in 0.05 M HCl and phosphate-buffered saline (PBS) (pH 6.5). In 0.05 M HCl, PVP-VA ASDs with low drug loading (<15%) showed rapid dissolution accompanied with nano-species generation, while in the PVP system, rapid dissolution and nano-species generation were observed only when drug loading was less than 10%, and HPMC-AS ASDs always released slowly with no nano-species formation. In PBS, PVP-VA ASDs with drug loading less than 10% showed rapid dissolution accompanied with nano-species generation, while for PVP ASDs, rapid dissolution and nano-species generation were observed only when drug loading was 5%. However, 20% drug loading HPMC-AS ASDs exhibited rapid dissolution of felodipine and nano-species generation. When the drug loading was above the transition point of PVP-VA ASDs and PVP ASDs, the release rate was significantly lowered, and no nano-species was generated. To understand this phenomenon, drug-polymer interactions were studied using the melting point depression method and the Flory-Huggins model fitting. The Flory-Huggins interaction parameters (χ) for felodipine/HPMC-AS, felodipine/PVP, and felodipine/PVP-VA were determined to be 0.62 ± 0.07, -0.55 ± 0.20, and -1.02 ± 0.21, respectively, indicating the existence of the strongest attractive molecular interaction between felodipine and PVP-VA, followed by felodipine/PVP, but not in felodipine/HPMC-AS. Furthermore, dynamic vapor sorption further revealed that the molecular interactions between felodipine and PVP or PVP-VA were resistant to water. We concluded that water-resistant drug-polymer interactions in felodipine/polymer systems were responsible for the formation of nano-species, which further facilitated the rapid initial drug dissolution.

Development of Simple Dissolution Methods for Felodipine and Combined Amlodipine Besylate-Indapamide Extended Release Tablets without Stationary (Felodipine) Basket.

BACKGROUND: The dissolution method for certain drugs needs specialized conditions. Dissolution testing for felodipine extended release (ER) tablets (Plendil® 5 mg) and amlodipine-indapamide fixed dose (Natrilam®, 5/1.5 mg) ER tablets requires the use of a stationary (felodipine) basket in USP Apparatus II. OBJECTIVE: The study aimed to develop simple methods for Plendil® and Natrilam® without the use of a felodipine basket. METHODS: The dissolution profiles obtained from different media and paddle speeds were used to compute miscellaneous dissolution parameters and were compared to those obtained from standard (existing) methods using a felodipine basket. RESULTS: The f1, f2, and bootstrap f2 (5th % percentile) values for Plendil® 2.47, 88.17, and 54.62, respectively, and all other dissolution factors revealed similarity between standard and the selected test method with 1% Tween 20 at 50 rpm. For Natrilam®, f1 and f2 and bootstrap f2 5.13, 72.92, and 62.67, respectively, and all other dissolution parameters showed similarity of the standard and selected test method using 0.1N HCl media having 0.38 gm/L EDTA with a sinker at 100 rpm. Release of products assumed zero-order and Weibull model, respectively. CONCLUSION: Test dissolution methods for Plendil® and Natrilam® tablets produced equivalent dissolution profiles compared to their respective standard methods with stationary basket USP Apparatus II.

Transfer of trace organic compounds in an operational soil-aquifer treatment system assessed through an intrinsic tracer test and transport modelling.

Soil Aquifer Treatment (SAT) can provide supplementary treatment of trace organic compounds (TrOCs) such as pharmaceutical and industrial compounds present in Secondary Treated Wastewater (STWW). Concern on presence of unregulated TrOCs in natural systems has raised recently as well as the interest in SAT systems for remediation. The present study quantifies, at the field scale over35 m of lateral groundwater flow, the effectiveness of the Agon-Coutainville SAT system (Manche, Normandy, France) for TrOCs removal by sorption and biodegradation through monitoring of seven TrOCs (oxazepam, carbamazepine, benzotriazole, tolyltriazole, caffein, paracetamol, ibuprofen) and major inorganic compounds as intrinsic tracers in STWW and groundwater during a 34-day STWW infiltration experiment during operational use of the SAT. Cationic exchanges and mixing between groundwater and STWW during the experiment were highlighted by major ions and geochemical simulations. Due to the low thickness of the unsaturated zone, a 1D analytical solution of the advection-dispersion equation (ADE) was applied on chloride data. Chloride was used as conservative intrinsic tracer to calibrate the horizontal flow and transport parameters such as the aquifer dispersion coefficient (D) and the average pore water velocity (ν) allowing estimation of the groundwater residence time. Transport and attenuation of the TrOCs were simulated assuming first-order degradation constant (µ) and linear retardation coefficient (R), calibrated to simulate the observed temporal changes in the breakthrough of TrOCs. Sorption was found to play a role in the transport of TrOCs, notably for oxazepam with a higher linear retardation coefficient value of 2.2, whereas no significant differences of retardation were observed for carbamazepine, tolyltriazole, benzotriazole (1.37, 1.35, 1.36 respectively). Estimated first order degradation rate constants, between 0.03d-1 for carbamazepine and 0.09d-1 for tolyltriazole, were generally high compared to the literature, possibly due to favourable redox conditions and important microbial activities within the system. This study provides evidence of the efficiency of the Agon-Coutainville SAT system for the removal of TrOCs.

Multicomponent Droplet Drying Modeling Based on Conservation and Population Balance Equations.

The aim of this work is to present a modeling tool to describe drying kinetics and delineate evolving physical and chemical behavior of multicomponent droplets during drying. Conservation equations coupled with population balance equations (PBE) are used to achieve this goal. Modeling results are gauged with single salt-water droplet drying from literature and show congruent trends. This model is then extended to a more complex system: various droplet sizes containing methanol (solvent), Felodipine (active ingredient), and PVP (polyvinylpyrrolidone as excipient). The FIB-SEM (Focused-Ion Beam Scanning Electron Microscopy) imaging results from spray-dried particles produced with similar formulation and processing conditions are consistent with phase behavior predicted by the model. The results show competing impacts of transport phenomena on the intermittent shell formation process and final particle structure and chemical heterogeneity. Solute diffusion, solvent efflux, and intra-drop flow impact the model system. It is found that shell formation follows a fluctuating profile where the initial precipitation of the dissolved species on the droplet surface is dampened, and nucleated particles become dispersed periodically until the shell becomes strong enough to withstand internal circulations. These internal effects are dependent on droplet size and are pronounced for larger droplets. That is, the particle phase behavior and physical nature are functions of the atomized droplet size. Stemming understating from this study would inform an optimized unit, operating in target design space. This would provide better product quality control and minimize discrepancies observed in process development during the early phase vs. commercial scale.

The Physical Stability of Felodipine and Its Recrystallization from an Amorphous Solid Dispersion Studied by NMR Relaxometry.

The 1H nuclear magnetic resonance (NMR) relaxometry method was applied to investigate the physical stability of an active pharmaceutical ingredient (API) and, for the first time, its recrystallization process in an amorphous solid dispersion system (ASD). The ASD of felodipine and polyvinylpyrrolidone (PVP) was prepared using the solvent evaporation method in a mass ratio of 50:50. In the first stage of the study (250 days), the sample was stored at 0% relative humidity (RH). The recovery of magnetization was described by one-exponential function. In the second stage (300 days in 75% relative humidity), the recrystallization process of felodipine was studied, showing in the sample three components of equilibrium magnetization related to (i) crystalline felodipine, (ii) water, and (iii) felodipine and PVP remaining in the ASD. The study shows that the 1H NMR relaxometry method is a very useful tool for analysing the composition of a three-phase system mixed at the molecular level and for the investigation of recrystallization process of API in amorphous solid dispersion system.

Micellar-emphasized simultaneous determination of ivabradine hydrochloride and felodipine using synchronous spectrofluorimetry.

A sensitive and green micellar spectrofluorimetric approach was applied for the simultaneous estimation of ivabradine hydrochloride (IVB) and felodipine (FLD) in the ng/ml concentration range. The approach depended on measuring the first derivative synchronous peak amplitude (1 D) of both drugs at ∆λ = 60 nm in a Tween-80 micellar system. The method was rectilinear alongside the concentration ranges 0.02-0.4 µg/ml and 0.05-1.0 µg/ml at 269.5 nm and 378.5 nm for IVB and FLD, respectively. The proposed method was validated by following the International Council for Harmonization guidelines. The method was successfully applied without interference for laboratory-prepared synthetic mixtures, single pharmaceutical preparations, and within spiked biological fluids with acceptable percentage recoveries. A comparison of the performance of the suggested method with other methods, showed no discrepancy. The method's ecofriendly property evaluated using three different tools, confirming an excellent green method.

Appraisal of Felodipine Nanocrystals for Solubility Enhancement and Pharmacodynamic Parameters on Cadmium Chloride Induced Hypertension in Rats.

AIM: Felodipine (FDP), an antihypertensive drug possesses low water solubility and extensive first-pass metabolism leading to poor bioavailability. This impelled us to improve its solubility, bioavailability, and pharmacodynamic properties through the Nanocrystal (NC) approach. METHODS: FDP-NC were prepared with Poloxamer F125 (PXM) by the antisolvent precipitation method. The experimental setup aimed at fine-tuning polymer concentration, the proportion of antisolvent to solvent, and the duration of ultrasonication for NC formulation. RESULTS: Optimized formulation was characterized for particle size, solubility, and PDI. Particle reduction of 74.96 times was achieved with a 9X solubility enhancement as equated to pure FDP. The morphology of NC was found to be crystalline through scanning electron microscopy observation. The formation of the crystal lattice in FDP-NC was further substantiated by the XRD and DSC results. Lowering of the heat of fusion of FDP-NC is a clear indication of size reduction. The stability studies showed no substantial change in physical parameters of the FDP-NC as assessed by particle size, zeta potential, and drug content. CONCLUSION: The crystalline nature and improved solubility of FDP-NC improve the dissolution profile and pharmacodynamic data. The stability study data ensure that FDP-NC can be safely stored at 25°C. It is revealed that FDP-NC had a better release profile and improved pharmacodynamic effects as evident from better control over heart rate than FDP.

Solvent influence on manufacturability, phase behavior and morphology of amorphous solid dispersions prepared via bead coating.

Bead coating or fluid-bed coating serves as an auspicious solvent-based amorphous solid dispersion (ASD) manufacturing technique in respect of minimization of potential physical stability issues. However, the impact of solvent selection on the bead coating process and its resulting pellet formulation is, to the best of our knowledge, never investigated before. This study therefore aims to investigate the influence of the solvent on the bead coating process itself (i.e. manufacturability) and on solid-state characteristics of the resulting ASDs coated onto beads. For this purpose, the drug-polymer system felodipine (FEL)-poly(vinylpyrrolidone-co-vinyl acetate) (PVP-VA) was coated onto microcrystalline cellulose (MCC) beads from acetonitrile (ACN), methanol (MeOH), ethanol (EtOH), acetone (Ac), 2-propanol (PrOH), dichloromethane (DCM) and ethyl acetate (EthAc). A drug loading screening approach with bead coating revealed analogous ability to manufacture high drug-loaded ASDs from the different organic solvents. The results show no correlation with crystallization tendency or with equilibrium solubility of the drug in the different solvents, nor with the solvent-dependent drug-polymer miscibility obtained from film casting experiments. Distinct coating morphologies were however observed for PVP-VA and FEL-PVP-VA ASDs deposited onto beads from the various solvents, which is attributed to differences in solvent evaporation kinetics.

NMR relaxometry in an investigation of the kinetics of the recrystallization of a three-phase system.

The method of 1H Nuclear Magnetic Resonance (NMR) relaxometry is applied to investigate the kinetics of the recrystallization of an active pharmaceutical ingredient (felodipine) from the amorphous phase of its physical mixture with a polymer (polyvinylpyrrolidone, PVP). Comparison of the recrystallization results obtained for amorphous felodipine and its mixtures with PVP shows that the recrystallization process of API is faster in the mixtures and depends on the content of water in the system. The free induction decay (FID) for protons that were detected are composed of three components, and the loss of water from PVP strongly influences the part characterized by the longest spin-spin lattice relaxation time. Analysis of the FID of the physical mixture indicates that the content of water does not change during the recrystalization process. The study shows that the T11H NMR relaxometry method is very useful for analysing the composition of a three-phase mixture and the recrystallization process.

"Felodipine-indomethacin" co-amorphous supersaturating drug delivery systems: "Spring-parachute" process, stability, in vivo bioavailability, and underlying molecular mechanisms.

Amorphous solid dispersions (ASD) are one of most commonly used supersaturating drug delivery systems (SDDS) to formulate insoluble active pharmaceutical ingredients. However, the development of polymer-guided stabilization of ASD systems faces many obstacles. To overcome these shortcomings, co-amorphous supersaturable formulations have emerged as an alternative formulation strategy for poorly soluble compounds. Noteworthily, current researches around co-amorphous system (CAS) are mostly focused on preparation and characterization of these systems, but more detailed investigations of their supersaturation ("spring-parachute" process), stability, in vivo bioavailability and molecular mechanisms are inadequate and need to be clarified. In present study, we chose pharmacological relevant BCS II drugs to fabricate and characterize "felodipine-indomethacin" CAS. To enrich the current inadequate but key knowledge on CAS studies, we carried out following highlighted investigations including dissolution/solubility, semi-continuous "spring-parachute" process, long-term stability profile of amorphous state, in vivo bioavailability and underlying molecular mechanisms (molecular interaction, molecular miscibility and crystallization inhibition). Generally, the research provides some key information in the field of current "drug-drug" CAS supersaturable formulations.

Insights into the ameliorating ability of mesoporous silica in modulating drug release in ternary amorphous solid dispersion prepared by hot melt extrusion.

In this work, the application of various mesoporous silica grades in the preparation of stabilized ternary amorphous solid dispersions of Felodipine using hot melt extrusion was explored. We have demonstrated the effectiveness of mesoporous silica in these dispersions without the need for any organic solvents i.e., no pre-loading or immersion steps required. The physical and chemical properties, release profiles of the prepared formulations and the surface concentrations of the various molecular species were investigated in detail. Formulations containing 25 wt% and 50 wt% of Felodipine demonstrated enhanced stability and solubility of the drug substance compared to its crystalline counterpart. Based on the Higuchi model, ternary formulations exhibited a 2-step or 3-step release pattern which can be ascribed to the release of drug molecules from the organic polymer matrix and the external silica surface, followed by a release from the silica pore structure. According to the Korsmeyer-Peppas model, the release rate and release mechanism are governed by a complex quasi-Fickian release mechanism, in which multiple release mechanisms are occurring concurrently and consequently. Stability studies indicated that after 6 months storage of all formulation at 30% RH and 20 °C, Felodipine in all formulations remained stable in its amorphous state except for the formulation comprised of 40 wt% Syloid AL-1FP with a 50 wt% drug load.

Cell culture-based production and in vivo characterization of purely clonal defective interfering influenza virus particles.

BACKGROUND: Infections with influenza A virus (IAV) cause high morbidity and mortality in humans. Additional to vaccination, antiviral drugs are a treatment option. Besides FDA-approved drugs such as oseltamivir or zanamivir, virus-derived defective interfering (DI) particles (DIPs) are considered promising new agents. IAV DIPs typically contain a large internal deletion in one of their eight genomic viral RNA (vRNA) segments. Consequently, DIPs miss the genetic information necessary for replication and can usually only propagate by co-infection with infectious standard virus (STV), compensating for their defect. In such a co-infection scenario, DIPs interfere with and suppress STV replication, which constitutes their antiviral potential. RESULTS: In the present study, we generated a genetically engineered MDCK suspension cell line for production of a purely clonal DIP preparation that has a large deletion in its segment 1 (DI244) and is not contaminated with infectious STV as egg-derived material. First, the impact of the multiplicity of DIP (MODIP) per cell on DI244 yield was investigated in batch cultivations in shake flasks. Here, the highest interfering efficacy was observed for material produced at a MODIP of 1E-2 using an in vitro interference assay. Results of RT-PCR suggested that DI244 material produced was hardly contaminated with other defective particles. Next, the process was successfully transferred to a stirred tank bioreactor (500 mL working volume) with a yield of 6.0E+8 PFU/mL determined in genetically modified adherent MDCK cells. The produced material was purified and concentrated about 40-fold by membrane-based steric exclusion chromatography (SXC). The DI244 yield was 92.3% with a host cell DNA clearance of 97.1% (99.95% with nuclease digestion prior to SXC) and a total protein reduction of 97.2%. Finally, the DIP material was tested in animal experiments in D2(B6).A2G-Mx1r/r mice. Mice infected with a lethal dose of IAV and treated with DIP material showed a reduced body weight loss and all animals survived. CONCLUSION: In summary, experiments not only demonstrated that purely clonal influenza virus DIP preparations can be obtained with high titers from animal cell cultures but confirmed the potential of cell culture-derived DIPs as an antiviral agent.