Solid dispersions with hydrogenated castor oil increase solubility, dissolution rate and intestinal absorption of praziquantel

Extrusion and 3D printing of novel lipid-polymer blends for oral drug applications

Lipids are interesting biological materials that can offer a number of pharmaceutical benefits when used as carriers for drug delivery. However, 3D printing of lipids alone by fused deposition processing techniques is very difficult as they have very poor mechanical properties that cause their filaments to fail when they are loaded into a fused deposition 3D printer. If this problem could be overcome, then lipids could be 3D printed into bespoke tablets and assist progress towards such personalised medicines. This work aims to improve the mechanical properties of lipid filaments by developing novel lipid-EVA (ethylene vinyl acetate) blends suitable for 3D printing. Different types of lipids in varying proportions were melt blended with EVA and extruded using a micro compounder. The ultimate printability of the materials was tested by feeding the filaments into a material extrusion 3D printer. Flexural testing of the extruded blends demonstrates that a good balance between the strength and flexibility is required for a material to be printable and it was found that a filament has to have a modulus/strength ratio between 8 and 25 in order to be printable. SEM analysis of the fracture surface shows a network structure within the lipid matrix that could be playing a role in the improved properties of the best performing blends. DSC thermograms show a shift in thermal transitions, suggesting some level of miscibility of the components that could have contributed to a more robust structure. The TGA results show an onset of degradation of the blends greater than 200 °C, indicating that the materials can readily withstand the extrusion and printing temperatures. This study demonstrates the successful extrusion and 3D printing of novel EVA-lipid blends with lipid contents of up to 90%.

Formulation of amorphous ternary solid dispersions of dapagliflozin using PEG 6000 and Poloxamer 188: solid-state characterization, ex vivo study, and molecular simulation assessment

The present study was designed to prepare dapagliflozin (DFG) loaded ternary solid dispersions (SDs) using the carrier blend polyethylene glycol 6000 (PEG 6000) and poloxamer 188 (PLX 188). The prepared DFG-SDs were evaluated for solubility study, physicochemical characterization and molecular simulation study. The prepared DFG-SDs showed significant higher solubility and dissolution vis-a-vis pure DFG and DFG physical mixture. The composition DFG:PEG:PLX (1:2.25:0.75 mM) showed the highest solubility (0.476 ± 0.016 mg/mL). The physicochemical characterization confirms the polymorphic transition of DFG from crystalline state to stable amorphous form. The prepared DFG-SDs showed a significantly higher dissolution (64.78 ± 2.34% to 78.41 ± 2.39%) than pure DFG (15.70 ± 3.54%). DFG-SD2 showed a significantly enhanced drug permeation (p<.05) (58.76 ± 4.65 µg/cm) as compared to pure DFG (14.97 ± 3.32 µg/cm). The molecular docking study result revealed a good hydrophobic interaction of DFG with the used carrier due to the lowest energy pose. The interaction occurs between the methylene bridges and the central hydrophobic chain of polyoxypropylene of the polymer. Therefore, DFG-SDs prepared by microwave irradiation method using hydrophilic carrier blend might be a promising strategy for improving the solubility and in vitro dissolution performance.

Oral nanoparticles based on gellan gum/pectin for colon-targeted delivery of resveratrol

Nanoparticles based on gellan gum/pectin blends were designed for colon-targeted release of resveratrol (RES). Their impact on drug release rates and permeability were evaluated using Caco-2 cell model and mucus secreting triple co-culture model. Polymeric nanoparticles (PNP) were successfully prepared by nebulization/ionotropic gelation, achieving high drug loading (>80%). PNP were spherical with a low positive charge density (+5mV) and exhibited diameters of around 330 nm. Developed PNP were able to promote effective modulation of drug release rates, so that only 3% of RES was released in acidic media over 2 h, and, in pH 6.8, the drug was released in a sustained manner, reaching 85% in 30 h. The permeability of RES-loaded PNP in the Caco-2 model was 0.15%, while in the triple co-culture model, in the presence of mucus, it reached 5.5%. The everted gut sac experiment corroborated the low permeability of RES-loaded PNP in the presence or absence of mucus and highlighted their high ability to interact with the intestinal tissue. Results indicate that the novel PNP developed in this work are safe and promising carriers for controlled delivery of RES at the colon.

Praziquantel-Solid Lipid Nanoparticles Produced by Supercritical Carbon Dioxide Extraction: Physicochemical Characterization, Release Profile, and Cytotoxicity

Solid lipid nanoparticles (SLNs) can be produced by various methods, but most of them are difficult to scale up. Supercritical fluid (SCF) is an important tool to produce micro/nanoparticles with a narrow size distribution and high encapsulation efficiency. The aim of this work was to produce cetyl palmitate SLNs using SCF to be loaded with praziquantel (PZQ) as an insoluble model drug. The mean particle size (nm), polydispersity index (PdI), zeta potential, and encapsulation efficiency (EE) were determined on the freshly prepared samples, which were also subject of Differential Scanning Calorimetry (DSC), Fourier-Transform Infrared Spectroscopy (FTIR), drug release profile, and in vitro cytotoxicity analyses. PZQ-SLN exhibited a mean size of ~25 nm, PdI ~ 0.5, zeta potential ~−28 mV, and EE 88.37%. The DSC analysis demonstrated that SCF reduced the crystallinity of cetyl palmitate and favored the loading of PZQ into the lipid matrices. No chemical interaction between the PZQ and cetyl palmitate was revealed by FTIR analysis, while the release or PZQ from SLN followed the Weibull model. PZQ-SLN showed low cytotoxicity against fibroblasts cell lines. This study demonstrates that SCF may be a suitable scale-up procedure for the production of SLN, which have shown to be an appropriate carrier for PZQ.

Structural Elucidation of Poloxamer 237 and Poloxamer 237/Praziquantel Solid Dispersions: Impact of Poly(Vinylpyrrolidone) over Drug Recrystallization and Dissolution

Praziquantel (PZQ) is the recommended, effective, and safe treatment against all forms of schistosomiasis. Solid dispersions (SDs) in water-soluble polymers have been reported to increase solubility and bioavailability of poorly water-soluble drugs like PZQ, generally due to the amorphous form stabilization. In this work, poloxamer (PLX) 237 and poly(vinylpyrrolidone) (PVP) K30 were evaluated as potential carriers to revert PZQ crystallization. Binary and ternary SDs were prepared by the solvent evaporation method. PZQ solubility increased similarly with PLX either as binary physical mixtures or SDs. Such unpredicted data correlated well with crystalline PZQ and PLX as detected by solid-state NMR (ssNMR) and differential scanning calorimetry in those samples. Ternary PVP/PLX/PZQ SDs showed both ssNMR broad and narrow superimposed signals, thus revealing the presence of amorphous and crystalline PZQ, respectively, and exhibited the highest PZQ dissolution efficiency (up to 82% at 180 min). SDs with PVP provided a promising way to enhance solubility and dissolution rate of PZQ since PLX alone did not prevent recrystallization of amorphous PZQ. Based on ssNMR data, novel evidences on PLX structure and molecular dynamics were also obtained. As shown for the first time using ssNMR, propylene glycol and ethylene glycol constitute the PLX amorphous and crystalline components, respectively.

Preparation and evaluation of azithromycin binary solid dispersions using various polyethylene glycols for the improvement of the drug solubility and dissolution rate

ABSTRACT Azithromycin is a water-insoluble drug, with a very low bioavailability. In order to increase the solubility and dissolution rate, and consequently increase the bioavailability of poorly-soluble drugs (such as azithromycin), various techniques can be applied. One of such techniques is "solid dispersion". This technique is frequently used to improve the dissolution rate of poorly water-soluble compounds. Owing to its low solubility and dissolution rate, azithromycin does not have a suitable bioavailability. Therefore, the main purpose of this investigation was to increase the solubility and dissolution rate of azithromycin by preparing its solid dispersion, using different Polyethylene glycols (PEG). Preparations of solid dispersions and physical mixtures of azithromycin were made using PEG 4000, 6000, 8000, 12000 and 20000 in various ratios, based on the solvent evaporation method. From the studied drug release profile, it was discovered that the dissolution rate of the physical mixture, as the well as the solid dispersions, were higher than those of the drug alone. There was no chemical incompatibility between the drug and polymer from the observed Infrared (IR) spectra. Drug-polymer interactions were also investigated using Differential Scanning Calorimetry (DSC), Powder X-Ray Diffraction (PXRD) and Scanning Election Microscopy (SEM). In conclusion, the dissolution rate and solubility of azithromycin were found to improve significantly, using hydrophilic carriers, especially PEG 6000.

Design and development of SMEDDS for colon-specific drug delivery

CONTEXT

Lipoidal systems have particularly shown potential for specific accumulation in areas with inflamed tissue increasing the selectivity of local drug delivery.

OBJECTIVE

Formulation and evaluation of self-microemulsifying drug delivery system (SMEDDS) for colon-specific drug delivery for effective treatment of colonic diseases.

METHOD

Ternary phase diagram was used to optimize level of oil, surfactant and co-surfactant to optimize SMEDDS and were evaluated for percent transmittance, emulsification time, in vitro release, myeloperoxidase (MPO) activity and intestinal accumulation. The spray dried SMEDDS were filled in capsules which were enteric coated with Eudragit S-100 at 10% weight gain to ensure SMEDDS delivery at colon. The spray dried SMEDDS were also evaluated for IR, DSC, XRD, SEM and stability study.

RESULT

In ternary phase diagram, Capmul MCM C8 and Capmul PG12 NF with surfactant (Tween 20) and co-surfactant (PG) in ratio 2:1 and 3:1, respectively, showed maximum emulsification area. These liquid SMEDDS show maximum transmittance, globule size of 90-30 nm. The spray-dried SMEDDS with diluents show good flow property. The units of MPO activity show lower level as compared to pure drug and control group, histopathology results supports better healing with SMEDDS. This was attributed to accumulation of SMEDDS in inflammatory area as compared to drug which was further proved by accumulation study. Enteric-coated capsule containing SMEDDS are able to deliver drug, specifically at the colonic region.

CONCLUSION

Higher accumulation of lipoidal drug in inflammatory area and specific release of liposomes by enteric-coated capsules provide better option for the treatment of colonic disease.

Absorption enhancement studies of clopidogrel hydrogen sulphate in rat everted gut sacs

Objectives

Clopidogrel, a thienopyridine antiplatelet agent, is a poor aqueous soluble compound and a P-glycoprotein (P-gp) efflux pump substrate. These two factors are responsible for its incomplete intestinal absorption. In this study, we have attempted to enhance the absorption of clopidogrel by improving its solubility and by inhibiting intestinal P-gp activity.

Methods

Solubility enhancement was achieved by preparing solid dispersions. Quinidine and naringin were selected as P-gp inhibitors, whilst tartaric acid was selected as the intestinal absorption enhancer. Absorption studies were performed using the everted gut sac model prepared from rat jejunum. The determination of clopidogrel was performed by high performance liquid chromatography.

Key findings

We noticed an enhancement of clopidogrel absorption by improving its solubility or by inhibiting the P-gp activity. The greatest results were obtained for solid dispersions in the presence of P-gp inhibitors at their highest concentrations, with an absorption improvement of 3.41- and 3.91-fold for naringin (15 mg/kg) and quinidine (200 µm), respectively. However, no clopidogrel absorption enhancement occurred in the presence of tartaric acid.

Conclusions

Naringin, a natural compound which has no undesirable side effects as compared with quinidine, could be used as a pharmaceutical excipient in the presence of clopidogrel solid dispersions to increase clopidogrel intestinal absorption and therefore its oral bioavailability.