Enhanced rectal bioavailability of ibuprofen in rats by poloxamer 188 and menthol

Thermo-activated in situ rectal gel preparation for Ibuprofen using eutectic mixture

This study aimed to develop a thermosensitive in situ gel formulation for rectal delivery of Ibuprofen as an efficient alternative dosage form. Utilizing poloxamer 188, poloxamer 407, and HPMC via cold technique method, a thermosensitive in situ gel was successfully prepared. The concentration of Ibuprofen in the formulations was 1.2 % (w/w). The prepared gels underwent assessment for clarity, gelation temperature, gelation time, gel strength, spread ability, syringe-ability, pH, viscosity, FTIR, and drug content. The selected formulations exhibited a gelation temperature within the range of 30 °C to 36 °C, with consistent amount of drug soluble in the formulations (93 % - 110 %). Mucoadhesive studies, in vitro release tests, ex vivo modeling of drug release, kinetic studies modeling, and histopathology testing were also conducted. The formulation comprising 18 % poloxamer 407, 12 % poloxamer 188, and 1 % sodium chloride (FS15) demonstrated suitable gelation temperature and desirable drug release rate. In vitro drug release tests indicated completion within one hour for both FS10 (20 % P407 & 10 % P188) and FS15 (18 % P407 & 12 % P188), with consistent and predictable release patterns observed through kinetic modeling analysis. Microscopic histopathology examination confirmed the safety of the selected formula, exhibiting no irritation in the mucosal membrane of the sheep. In conclusion, Ibuprofen thermosensitive in situ gel presents a promising and convenient strategy as a rectal carrier and an alternative dosage form to solid suppositories.

Development of 3D-printed dual-release fixed-dose combination through double-melt extrusion

This study aimed to develop a 3D-printed fixed-dose combination tablet featuring differential release of two drugs using double-melt extrusion (DME). The hot-melt extrusion (HME) process was divided into two steps to manufacture a single filament containing the two drugs. In Step I, a sustained-release matrix of acetaminophen (AAP) was obtained through HME at 190 °C using Eudragit® S100, a pH-dependent polymer with a high glass transition temperature. In Step II, a filament containing both sustained-release AAP from Step I and solubilized ibuprofen (IBF) was fabricated via HME at 110 °C using a mixture of hydroxy propyl cellulose (HPC-LF) and Eudragit® EPO, whose glass transition temperatures make them suitable for use in a 3D printer. A filament manufactured using DME was used to produce a cylindrical 3D-printed fixed-dose combination tablet with a diameter and height of 9 mm. To evaluate the release characteristics of the manufactured filament and 3D-printed tablet, dissolution tests were conducted for 10 h under simulated gastrointestinal tract conditions using the pH jump method with the United States Pharmacopeia apparatus II paddle method at 37 ± 0.5 °C and 50 rpm. Dissolution tests confirmed that both the sustained-release and solubilized forms of AAP and IBF within the filament and 3D-printed tablet exhibited distinct drug-release behaviors. The physicochemical properties of the filament and 3D-printed tablet were confirmed by thermogravimetric analysis, differential scanning calorimetry, powder X-ray diffraction, and Fourier-transform infrared spectroscopy. HME transforms crystalline drugs into amorphous forms, demonstrating their physicochemical stability. Scanning electron microscopy and confocal laser scanning microscopy indicated the presence of sustained AAP granules within the filament, confirming that the drugs were independently separated within the filament and 3D-printed tablets. Finally, sustained-release AAP and solubilized IBF were independently incorporated into the filaments using DME technology. Therefore, a dual-release 3D-printed fixed-dose combination was prepared using the proposed filament.

Lopinavir-menthol co-crystals for enhanced dissolution rate and intestinal absorption

Lopinavir is an antiretroviral, antiparasitic agent and recently utilized in treatment of COVID-19. Unfortunately, lopinavir exhibited poor oral bioavailability due to poor dissolution, extensive pre-systemic metabolism, and significant P-glycoprotein intestinal efflux. Accordingly, the aim was to enhance dissolution rate and intestinal absorption of lopinavir. This employed co-processing with menthol which is believed to modify crystalline structures and inhibit intestinal efflux. Lopinavir was mixed with menthol at different molar ratios before ethanol assisted kneading. Formulations were evaluated using FTIR spectroscopy, differential scanning calorimetry (DSC), X-ray powder diffraction (XRD) and dissolution studies. Optimum ratio was utilized to assess lopinavir intestinal permeability. This employed in situ rabbit intestinal perfusion technique. FTIR, DSC and XRD indicated formation of lopinavir-menthol co-crystals at optimum molar ratio of 1:2. Additional menthol underwent phase separation due to possible self-association. Co-crystallization significantly enhanced lopinavir dissolution rate compared with pure drug to increase the dissolution efficiency from 24.96% in case of unprocessed lopinavir to 91.43% in optimum formulation. Lopinavir showed incomplete absorption from duodenum and jejuno-iliac segments with lower absorptive clearance from jejuno-ileum reflecting P-gp efflux. Co-perfusion with menthol increased lopinavir intestinal permeability. The study introduced menthol as co-crystal co-former for enhanced dissolution and augmented intestinal absorption of lopinavir.

Chitosan/guar gum-based thermoreversible hydrogels loaded with pullulan nanoparticles for enhanced nose-to-brain drug delivery

The biopolymers-based two-fold system could provide a sustained release platform for drug delivery to the brain resisting the mucociliary clearance, enzymatic degradation, bypassing the first-pass hepatic metabolism, and BBB thus providing superior bioavailability through intranasal administration. In this study, poloxamers PF-127/PF-68 grafted chitosan HCl-co-guar gum-based thermoresponsive hydrogel loaded with eletriptan hydrobromide laden pullulan nanoparticles was synthesized and subjected to dynamic light scattering, Fourier transform infrared spectroscopy, thermal analysis, x-ray diffraction, scanning electron microscopy, stability studies, mucoadhesive strength and time, gel strength, cloud point assessment, rheological assessment, ex-vivo permeation, cell viability assay, histology studies, and in-vivo Pharmacokinetics studies, etc. It is quite evident that CSG-EH-NPs T-Hgel has an enhanced sustained release drug profile where approximately 86 % and 84 % of drug released in phosphate buffer saline and simulated nasal fluid respectively throughout 48 h compared to EH-NPs where 99.44 % and 97.53 % of the drug was released in PBS and SNF for 8 h. In-vivo PKa parameters i.e., mean residence time (MRT) of 11.9 ± 0.83 compared to EH-NPs MRT of 10.2 ± 0.92 and area under the curve (AUC_tot) of 42,540.5 ± 5314.14 comparing to AUC_tot of EH-NPs 38,026 ± 6343.1 also establish the superiority of CSG-EH-NPs T-Hgel.

Novel Naproxen Salts with Increased Skin Permeability

The paper presents the synthesis, full identification, and characterization of new salts-L-proline alkyl ester naproxenates [ProOR][NAP], where R was a chain from ethyl to butyl (including isopropyl). All obtained compounds were characterized by Nuclear Magnetic Resonance (NMR), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffractometry (XRD), and in vitro dissolution studies. The specific rotation, phase transition temperatures (melting point), and thermal stability were also determined. In addition, their lipophilicity, permeability, and accumulation in pigskin were determined. Finally, toxicity against mouse L929 fibroblast cells was tested. The obtained naproxen derivatives showed improved solubility and higher absorption of drug molecules by biological membranes. Their lipophilicity was lower and increased with the increase in the alkyl chain of the ester. The derivative with isopropyl ester had the best permeability through pigskin. The use of L-proline isopropyl ester naproxenate increased the permeation of naproxen through the skin almost four-fold. It was also shown that the increase in permeability is not associated with additional risk: all compounds had a similar effect on cell viability as the parent naproxen.

Curcumin-laden hyaluronic acid-co-Pullulan-based biomaterials as a potential platform to synergistically enhance the diabetic wound repair

Injectable hydrogel with multifunctional tunable properties comprising biocompatibility, anti-oxidative, anti-bacterial, and/or anti-infection are highly preferred to efficiently promote diabetic wound repair and its development remains a challenge. In this study, we report hyaluronic acid and Pullulan-based injectable hydrogel loaded with curcumin that could potentiate reepithelization, increase angiogenesis, and collagen deposition at wound microenvironment to endorse healing cascade compared to other treatment groups. The physical interaction and self-assembly of hyaluronic acid-Pullulan-grafted-pluronic F127 injectable hydrogel were confirmed using nuclear magnetic resonance (¹H NMR) and Fourier transformed infrared spectroscopy (FT-IR), and cytocompatibility was confirmed by fibroblast viability assay. The CUR-laden hyaluronic acid-Pullulan-g-F127 injectable hydrogel promptly undergoes a sol-gel transition and has proved to potentiate wound healing in a streptozotocin-induced diabetic rat model by promoting 93% of wound closure compared to other groups having 35%, 38%, and 62%. The comparative in vivo study and histological examination was conducted which demonstrated an expeditious recovery rate by significantly reducing the wound healing days i.e. 35 days in a control group, 33 days in the CUR suspension group, 21 days in unloaded injectable, and 13 days was observed in CUR loaded hydrogel group. Furthermore, we suggest that the injectable hydrogel laden with CUR showed a prompt wound healing potential by increasing the cell proliferation and serves as a drug delivery platform for sustained and targeted delivery of hydrophobic moieties.

Sketching neoteric solvents for boosting drugs bioavailability

Emerging neoteric solvents are being the subject of growing attention due to their lower cost and environmental impact, so they are being applied in a broad spectrum of industries. Among them, the pharmaceutical sector is demanding new environmentally friendly and non-toxic solvents able to enhance drugs solubility and stability. The introduction of ionic liquids turned out to be a breakthrough in the field of Green Chemistry opening up new separation and catalysis opportunities. In this sense, the options represented by Deep Eutectic Solvents make up an attractive alternative due to the low cost of their raw material, simple synthesis, and eco-friendly character. In line with these findings, Therapeutic Deep Eutectic Solvents and Natural Deep Eutectic Solvents are new and promising alternatives to improve the bioavailability of drugs in pharmaceutical formulations. This leading article is focused on providing a general picture of the advantages and drawbacks of these new solvents as well as the main research lines and perspectives to achieve efficient drugs delivery systems.

Tolmetin sodium-loaded thermosensitive mucoadhesive liquid suppositories for rectal delivery; strategy to overcome oral delivery drawbacks

Tolmetin sodium (TS) is a nonsteroidal anti-inflammatory drug (NSAID) indicated for treatment of musculoskeletal issues. As other NSAID, TS displays a marked side effects on the gastro-intestinal (GI) tract after oral administration. Traditional solid suppositories can cause pain and discomfort for patients, may reach the end of the colon; consequently, the drug can undergo the first-pass effect. TS liquid suppository (TS-_LS) was developed to enhance patient compliance and rectal mucosal safety in high-risk patients receiving highly NSAID therapy. This work was conducted to optimize and evaluate Poloxamer P407/P188-based thermoresponsive TS-_LS by using mucoadhesive polymers such as methylcellulose (MC). TS-_LS was prepared by cold method and characterized their in vitro physicochemical properties as gelation temperature (GT), gel strength, bioadhesive properties, and in vitro release. The safety of the prepared suppository on rectum, stomach, and liver was evaluated histologically. Pharmacokinetic analyses were performed to compare rectal TS-_LS to orally Rhumtol^® capsules. The results showed that the optimized TS-_LS; composed of P407/P188/MC (21/9/0.5% w/w) displayed gelation at rectum temperature ∼32.90 °C, gel strength of 21.35 s and rectal retention force at the administration site of 24.25 × 10² dyne/cm². Moreover, TS-_LS did not cause any morphological damage to the rectal tissues. Pharmacokinetic parameters of optimized TS-_LS formulation revealed 4.6 fold increase in bioavailability as compared to Rhumtol^® capsules. Taken together, the results demonstrated that liquid suppository is a potential and physically safe rectal delivery carrier for improvement rectal bioavailability and in vivo safety of TS.

Thermosensitive heparin-poloxamer hydrogels enhance the effects of GDNF on neuronal circuit remodeling and neuroprotection after spinal cord injury

Traumatic spinal cord injury (SCI) results in paraplegia or quadriplegia, and currently, therapeutic interventions for axonal regeneration after SCI are not clinically available. Animal studies have revealed that glial cell-derived neurotrophic factor (GDNF) plays multiple beneficial roles in neuroprotection, glial scarring remodeling, axon regeneration and remyelination in SCI. However, the poor physicochemical stability of GDNF, as well as its limited ability to cross the blood-spinal cord barrier, hampers the development of GDNF as an effective therapeutic intervention in clinical practice. In this study, a novel temperature-sensitive heparin-poloxamer (HP) hydrogel with high GDNF-binding affinity was developed. HP hydrogels showed a supporting scaffold for GDNF when it was injected into the lesion epicenter after SCI. GDNF-HP by orthotopic injection on lesioned spinal cord promoted the beneficial effects of GDNF on neural stem cell proliferation, reactive astrogliosis inhibition, axonal regeneration or plasticity, neuroprotection against cell apoptosis, and body functional recovery. Most interestingly, GDNF demonstrated a bidirectional regulation of autophagy, which inhibited cell apoptosis at different stages of SCI. Furthermore, the HP hydrogel promoted the inhibition of autophagy-induced apoptosis by GDNF in SCI. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2816-2829, 2017.

– (-) Menthol Induces Reversal of Promoter Hypermethylation and Associated Up-Regulation of the FANCF Gene in the SiHa Cell Line

Objective:

To identify natural bioactive molecules with potential to inhibit DNA methyltransferase 1 (DNMT1) and cause reactivation of genes silenced due to promoter hypermethylation.

Methods and Results:

-(-) Menthol and epigallocatechin-3-gallate (EGCG) (reference molecule) were investigated using an in vitro methylation assay, which indicated potential of -(-) menthol as an epigenetic modulator with the ability to directly inhibit M.SssI (an analogue of DNMT1) activity at 100µM. Methylation specific PCR and bisulphite sequencing revealed complete hypomethylation of 15 CpG sites in the Fanconi anemia, complementation group F (FANCF) gene between +280 and + 432 nucleotides relative to the transcription start site, which resulted in significant (P<0.001) up-regulation of FANCF gene expression by 2.1 and 2.5 fold respectively after treatment with menthol (80µM) and EGCG (80µM) for 4 days in the SiHa cell line as analyzed by qRT PCR.

Conclusion:

The present work highlighted the potential of -(-) menthol, a naturally occurring cyclic monoterpene, as an epigenetic modulator causing promoter hypomethylation induced reactivation of the FANCF gene mediated by possible inhibition of DNMT1 activity in the SiHa cell line.

The influence of bile salt on the chemotherapeutic response of docetaxel-loaded thermosensitive nanomicelles

The primary aim of this work was to investigate the potential of bile salt, sodium taurocholate (NaTC), in improving the bioavailability and anti-tumor efficacy of docetaxel (DCT) upon rectal administration. Poloxamer-based nanomicelles with thermosensitive and mucoadhesive properties were prepared using the cold method. The optimized nanomicellar formulation was evaluated in terms of physicochemical and viscoelastic parameters. Nanomicelles containing bile salt maintained sufficient gelation strength (234×10² mPa·s) and mucoadhesive force (17.3×10² dyne/cm²) to be retained in the upper part of the rectum. They significantly enhanced the DCT internalization across the rectal mucosa and showed a high plasma level during the first 4 hours of the study period, compared to nanomicelles with no bile salt. As a result, a slightly higher rectal bioavailability of ~33% was observed in nanomicelles containing bile salt, compared to ~28% from the latter system. The higher pharmacokinetic parameters for rectally administered DCT/P407/P188/Tween 80/NaTC (0.25%/11%/15%/10%/0.1% by weight, respectively) resulted in significant anti-tumor efficacy. However, the tumor regression rate for the NaTC group was not statistically different from that for nanomicelles without NaTC. Therefore, overall results suggest that thermosensitive nanomicelles could be a potential dosage form for improvement of the bioavailability and chemotherapeutic profile of DCT.

Evaluation of a novel thermosensitive heparin-poloxamer hydrogel for improving vascular anastomosis quality and safety in a rabbit model

Despite progress in the design of advanced surgical techniques, stenosis recurs in a large percentage of vascular anastomosis. In this study, a novel heparin-poloxamer (HP) hydrogel was designed and its effects for improving the quality and safety of vascular anastomosis were studied. HP copolymer was synthesized and its structure was confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (¹H-NMR). Hydrogels containing HP were prepared and their important characteristics related to the application in vascular anastomosis including gelation temperature, rheological behaviour and micromorphology were measured. Vascular anastomosis were performed on the right common carotid arteries of rabbits, and the in vivo efficiency and safety of HP hydrogel to achieve vascular anastomosis was verified and compared with Poloxamer 407 hydrogel and the conventional hand-sewn method using Doppler ultrasound, CT angiograms, scanning electron microscopy (SEM) and histological technique. Our results showed that HP copolymer displayed special gel-sol-gel phase transition behavior with increasing temperature from 5 to 60 °C. HP hydrogel prepared from 18 wt% HP solution had a porous sponge-like structure, with gelation temperature at approximately 38 °C and maximum elastic modulus at 10,000 Pa. In animal studies, imaging and histological examination of rabbit common jugular artery confirmed that HP hydrogel group had similar equivalent patency, flow and burst strength as Poloxamer 407 group. Moreover, HP hydrogel was superior to poloxamer 407 hydrogel and hand-sewn method for restoring the functions and epithelial structure of the broken vessel junctions after operation. By combining the advantages of heparin and poloxamer 407, HP hydrogel holds high promise for improving vascular anastomosis quality and safety.

Docetaxel-loaded thermosensitive liquid suppository: optimization of rheological properties

The main purpose of this work was to optimize the rheological properties of docetaxel (DCT)-loaded thermosensitive liquid suppositories for rectal administration. DCT-loaded liquid suppositories were prepared by a cold method and characterized in terms of physicochemical and viscoelastic properties. Major formulation parameters including poloxamer (P407) and Tween 80 were optimized to adjust the thermogelling and mucoadhesive properties for rectal administration. Notably, the gel strength and mucoadhesive force significantly increased with the increase in these variables. Furthermore, DCT incorporation did not alter the viscoelastic behavior, and the mean particle size of nanomicelles in it was approximately 16 nm with a distinct spherical shape. The formulation existed as liquid at room temperature and transformed into gel at physiological temperature through the reverse gelation phenomenon. Thus, DCT-loaded thermosensitive liquid suppositories [DCT/P407/P188/Tween 80 (0.25/11/15/10 %)] with optimal gel properties were easy to prepare and administer rectally, and might enable the gel to stay in the rectum without getting out from rectum.

Preparation and evaluation of solid dispersions of a new antitumor compound based on early-stage preparation discovery concept

Ensuring sufficient drug solubility is a crucial problem in pharmaceutical-related research. For water-insoluble drugs, various formulation approaches are employed to enhance the solubility and bioavailability of lead compounds. The goal of this study was to enhance the dissolution and absorption of a new antitumor lead compound, T-OA. Early-stage preparation discovery concept was employed in this study. Based on this concept, a solid dispersion system was chosen as the method of improving drug solubility and bioavailability. Solid dispersions of T-OA in polyvinylpyrrolidone (PVP) K30 were prepared by the solvent evaporation method. Dissolution testing determined that the ideal drug-to-PVP ratio was 1:5. X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry were employed to confirm the formation of solid dispersions. Scanning electron microscopy demonstrated that T-OA was converted into an amorphous form. Both in vitro dissolution testing and the in vivo studies demonstrated that the solubility and bioavailability of T-OA were significantly improved when formulated in a solid dispersion with PVP. The dissolution rate of the T-OA/PVP solid dispersion was greatly enhanced relative to the pure drug, and the relative bioavailability of T-OA solid dispersions was found to be 392.0%, which is 4-fold higher than the pure drug.

Docetaxel-loaded thermosensitive and bioadhesive nanomicelles as a rectal drug delivery system for enhanced chemotherapeutic effect

PURPOSE

To investigate the potential of thermosensitive and biadhesive nanomicelles in improving the bioavailability of docetaxel (DCT) and its chemotherapeutic effect.

METHOD

DCT-loaded nanomicelles were prepared by emulsufication and characterized in terms of physico-chemical and visco-elastic parameters. The optimzed formulation was evaluated for in vivo localization, pharmacokinetic and anti-tumor efficacy.

RESULTS

The hydrodynamic size of DCT-loaded nanomicelles was approximately 13 nm and the nanomicelles exhibited a sufficient gelation strength (9250 mPa·s) and bioadhesive force (2100 dyn/cm²) to be retained in the upper part of rectum. We observed a high rectal bioavailability of 29% DCT compared to that following oral administration in rats, as it successfully evaded the multidrug efflux transporters and hepatic first-pass metabolism. Plasma concentration around ∼50 ng/mL was maintained throughout the study period (12 h) while Taxotere® attained subtherapeutic range within 4 h of drug administration. Results also revealed that the rectally administered DCT-loaded nanomicelles exhibited a significant anti-tumor effect (200 mm³) with a reduced toxicity profile when compared to orally administered DCT (950 mm³). Furthermore, histological study showed that the rectal mucosa was completely intact with no signs of irritation upon treatment with DCT-loaded nanomicelles.

CONCLUSIONS

Taken together, our novel thermosensitive and biadhesive nanomicelles demonstrated the ability to improve the bioavailability and chemotherapeutic potential of DCT in vivo. To the best of our knowledge, this is the first report describing the rectal delivery of DCT-loaded nanomicelles.

Development of novel ibuprofen-loaded solid dispersion with enhanced bioavailability using cycloamylose

To develop a novel ibuprofen-loaded solid dispersion with enhanced bioavailability using cycloamylose, it was prepared using spray-drying techniques with cycloamylose at a weight ratio of 1:1. The effect of cycloamylose on aqueous solubility of ibuprofen was investigated. The physicochemical properties of solid dispersions were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction. The dissolution and bioavailability in rats were evaluated compared with ibuprofen powder. This ibuprofen-loaded solid dispersion improved about 14-fold drug solubility. Ibuprofen was present in an unchanged crystalline state, and cycloamylose played the simple role of a solubilizing agent in this solid dispersion. Moreover, the dispersion gave 2-fold higher AUC (area under the drug concentration-time curve) value compared with a ibuprofen powder, indicating that it improved the oral bioavailability of ibuprofen in rats. Thus, the solid dispersion may be useful to deliver ibuprofen with enhanced bioavailability without crystalline change.

Enhanced intestinal absorption of daidzein by borneol/menthol eutectic mixture and microemulsion

In the present study, the effect of a borneol/menthol eutectic mixture (25:75) and microemulsion on the absorption of daidzein in rat intestinal membrane was evaluated. The microemulsion formulation was composed of ethyl oleate (oil), Cremophor RH40 (surfactant), PEG400 (co-surfactant), and water. The borneol/menthol eutectic mixture and its microemulsion were found to enhance the intestinal absorption of daidzein in vitro. A diffusion chamber system with isolated rat intestinal membranes was used. In contrast, verapamil (0.3 mM), a typical P-glycoprotein inhibitor, showed no effect on the absorption of daidzein by this system. A pharmacokinetic study was conducted in rats. After oral administration of daidzein at a dose of 10 mg/kg in the form of either borneol/menthol eutectic mixtures or suspension, the relative bioavailability of borneol/menthol eutectic mixtures and microemulsion was enhanced by about 1.5- and 3.65-fold, respectively, compared with a daidzein suspension. In conclusion, a borneol/menthol eutectic mixture can enhance the absorption of daidzein, although the mechanism of absorption enhancement is still unclear.

Preparation of nanoparticles of Magnolia bark extract by rapid expansion from supercritical solution into aqueous solutions

A rapid expansion from supercritical solution into aqueous solution (RESSAS) technology was presented for the micronization of Chinese medicinal material. Magnolia bark extract (MBE) obtained by supercritical carbon dioxide (scCO₂) extraction technology was chosen as the experimental material. RESSAS process produced 303.0 nm nanoparticles (size distribution, 243.6-320.5 nm), which was significantly smaller than the 55.3 µm particles (size distribution, 8.3-102.4 µm) prepared by conventional mechanical milling. The effect of process parameters, including extraction temperature (30 °C, 40 °C, 50 °C), extraction pressure (200, 250, 300 bar) and nozzle size (50, 100, 200 µm), on the size distribution of nanoparticles was investigated. The characteristics of nanoparticles and materials were also studied by scanning electron microscopy (SEM) and laser light scattering (LLS). This study demonstrates that RESSAS is applicable for preparing nanoparticles of MBE at low operating temperature; the process is simple without any residual solvent.

Development of an itraconazole-loaded gelatin microcapsule with enhanced oral bioavailability: physicochemical characterization and in-vivo evaluation

OBJECTIVES

The aim of this study was to develop a novel itraconazole-loaded gelatin microcapsule without ethanol with enhanced oral bioavailability.

METHODS

Various gelatin microcapsules were prepared using a spray-drying technique. Their physicochemical properties, dissolution, characteristics and pharmacokinetics in rats were evaluated and compared with those of a commercial product.

KEY FINDINGS

The gelatin microcapsule at a weight ratio for itraconazole/gelatin/citric acid of 1 : 3 : 0.3 was spherical in shape with a smooth surface and inner hole, and gave a maximum drug solubility of about 700 microg/ml. The gelatin microcapsule dramatically increased the initial dissolution rate of itraconazole compared with a commercial product in simulated gastric fluids (pH 1.2). Moreover, at the same dose as the commercial product, it gave significantly higher initial plasma concentrations, C(max) and AUC of itraconazole in rats than did the commercial product, indicating that providing the drug in the gelatin microcapsule caused enhanced absorption in rats. At half dose, it gave similar AUC, C(max) and T(max) values to the commercial product, suggesting that it was bioequivalent to the commercial product in rats.

CONCLUSIONS

The itraconazole-loaded gelatin microcapsule without ethanol developed using a spray-drying technique at half the dose of the commercial product can deliver itraconazole in a pattern that allows fast absorption in the initial phase, making it bioequivalent to the commercial product.

Evaluation of mucoadhesive hydrogels loaded with diclofenac sodium-chitosan microspheres for rectal administration

Considering the advantageous for the rectal administration of non-steroidal anti-inflammatory drugs, the objective of this study was to formulate and evaluate rectal mucoadhesive hydrogels loaded with diclofenac-sodium chitosan (DFS-CS) microspheres. Hydroxypropyl methylcellulose (HPMC; 5%, 6%, and 7% w/w) and Carbopol 934 (1% w/w) hydrogels containing DFS-CS microspheres equivalent to 1% w/w active drug were prepared. The physicochemical characterization revealed that all hydrogels had a suitable pH for rectal application (6.5-7.4). The consistency of HPMC hydrogels showed direct proportionality to the concentration of the gelling agent, while carbopol 934 gel showed its difficulty for rectal administration. Farrow's constant for all hydrogels were greater than one indicating pseudoplastic flow. In vitro drug release from the mucoadhesive hydrogel formulations showed a controlled drug release pattern, reaching 34.6-39.7% after 6 h. The kinetic analysis of the release data revealed that zero-order was the prominent release mechanism. The mucoadhesion time of 7% w/w HPMC hydrogel was 330 min, allowing the loaded microspheres to be attached to the surface of rectal mucosa. Histopathological examination demonstrated the lowest irritant response to the hydrogel loaded with DFS-CS microspheres in response to other forms of the drug.

Effect of zinc oxide on the rheological and mucoadhesive properties of poloxamer 407-based mucoadhesive thermosensitive gel

BACKGROUND

To improve the therapeutic efficacy of drugs for hemorrhoid, mucoadhesive thermosensitive gel (MTG) system was developed.

METHODS

The MTG was prepared using poloxamer 407 (P407, 13% and 14%), polycarbophil (PC, 0.2% w/v), phenylephrine hydrochloride (0.25% w/v), lidocaine hydrochloride (1.88% w/v), and prednisolone acetate (0.05% w/v). Then, zinc oxide (ZnO) was added as an astringent as well as mucoadhesiveness-enhancing agent. Two kinds of poloxamer-based MTGs were compared in aspects of rheology, mucoadhesiveness, syringeability, and in vitro release study.

RESULTS

Both the two MTGs (13% and 14% P407) showed Newtonian behavior at 20°C whereas pseudoplastic flow at 37°C. The addition of ZnO into MTGs enhanced the mucoadhesiveness and syringeability and led the drug components to be released in accordance with Fickian mechanism.

CONCLUSIONS

Taken together, the MTG-containing ZnO can be a more effective and convenient delivery system for the treatment of hemorrhoid with a reduced dosage interval.

Micronization of magnolia bark extract with enhanced dissolution behavior by rapid expansion of supercritical solution

A rapid expansion of supercritical solution (RESS) technology was presented for the micronization of Chinese medicinal material. Magnolia bark extract (MBE) obtained by supercritical carbon dioxide (scCO(2)) extraction technology was chosen as the experimental material. RESS process produced 4.7 microm size MBE microparticles (size distribution, 0.2-24.1 microm), which was significantly smaller than the 55.3 microm size particles (size distribution, 8.3-102.4 microm) obtained from conventional mechanical milling. Dissolution rate study showed that drug dissolution was significantly enhanced by the RESS progress. At 90 min, the amount dissolved of mechanical milling MBE was 6.37 mg x l(-1), which was significantly lower than that of micronized MBE (14.77 mg x l(-1)), according to the results of ANOVA (p<0.01). The effect of extraction temperature (30, 40, 50 degrees Celsius), extraction pressure (200, 250, 300 bar) and nozzle size (50, 100, 200 microm) on the size distribution of microparticles was investigated. The characteristics of microparticles were also studied by differential scanning calorimetry (DSC), infrared spectroscopy (IR), scanning electron microscopy (SEM), and image analysis. This study demonstrates that RESS is applicable for preparing microparticles of MBE at low operating temperature; the process is simple without residual solvent.

Enhanced oral bioavailability of flurbiprofen by combined use of micelle solution and inclusion compound

The main purpose of this study was to evaluate the effect of a mixed drug solution containing a surfactant and beta-cyclodextrin (beta-CD) on the solubility and bioavailability of a poorly water soluble drug, flurbiprofen. Solubility, dissolution and in vivo pharmacokinetics of flurbiprofen in the presence of surfactant, beta-CD or mixture of surfactant and beta-CD were investigated. Among the surfactants tested, Tween 80 produced the highest improvement in the aqueous solubility of flurbiprofen. The solubility of flurbiprofen increased linearly as a function of beta-CD, resulting in B8 type that suggested a formation of inclusion complex in a molar ratio of 1:1. The solubility of flurbiprofen increased further when Tween 80 was included in addition to beta-CD, suggesting that a micelle formation in the presence of Tween 80 was the likely reason for additional increase. Furthermore, the data suggested that Tween 80 did not interfere with the inclusion interaction between flurbiprofen and beta-CD. The solubility of flurbiprofen was the highest in the mixed system containing 1.3 mM beta-CD and 0.3% w/v Tween 80, and the maximum solubility of 160 microg/mL was achieved. Consistent with the enhanced solubility, the plasma exposure (both AUC and Cmax) of flurbiprofen when dosed as the mixed system was significantly higher (as much as 2 to 3-fold) than that without surfactant or beta-CD, with surfactant alone, or with beta-CD alone. Therefore, the mixed system consists of surfactant and beta-CD could be used as an effective oral dosage form to improve bioavailability of poorly water soluble drugs such as flurbiprofen.

Preparation and in vitro evaluation of solid dispersions of total flavones of Hippophae rhamnoides L

The purpose of this study was to enhance the dissolution of total flavones of Hippophae rhamnoides L. (TFH) by solid dispersions consisting of the drug and a polymeric carrier, poloxamer 188 (PXM). The solvent evaporation method was used to prepare solid dispersions. A 3(2) full-factorial design approach was used for optimization wherein the amount of solvent (X(1)) and the drug-to-polymer ratio (X(2)) were selected as independent variables and the percentage of TFH dissolved in 10 min (Q(10)) was selected as the dependent variable. Multiple linear regression analysis revealed that a suitable level of (1) and X(2) was required for obtaining higher dissolution of TFH from PXM solid dispersions. Solid dispersions were characterized by differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and dissolution tests. Characterization studies revealed that solid dispersion of TFH-PXM showed enhancement of TFH dissolution due to the conversion of TFH into a less crystalline and/or amorphous form. In conclusion, dissolution enhancement of TFH was obtained by preparing its solid dispersions in PXM using solvent method.

Micronization and microencapsulation of felodipine by supercritical carbon dioxide

Felodipine (FLD) is a poorly water-soluble drug. To improve its dissolution rate, the rapid expansion of supercritical solutions (RESS) technique was used to prepare micronized FLD drug particles, which were encapsulated in poly-(ethylene glycol) 4000 (PEG 4000). The physical properties of the encapsulated drug particles were characterized by a variety of analytical methods, including optical light microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and powder X-ray diffraction (powder-XRD) and the dissolution behaviour of FLD was studied in the microparticles. The supercritical condition of micronized FLD occurred at a relatively high pressure and moderate temperature. FLD-PEG 4000 microparticles compared well with micronized FLD. RESS was effective in reducing the particle size of FLD; spot-shaped micronized FLD and popcorn-shaped FLD-PEG 4000 microparticles were observed. The particulate properties of the microparticles included a narrow distribution and uniform size. Thermodynamic analysis showed an implantation interaction between FLD and PEG 4000 molecules, but no polymorphism in the micronized FLD or FLD-PEG 4000 microparticles. FLD-PEG 4000 microparticles had a significantly faster drug dissolution rate than micronized FLD. These data show that RESS can be used to prepare FLD-PEG 4000 microparticles with small particle size (2-6 microm) and enhanced dissolution rate.

Enhanced Oral Bioavailability of Ibuprofen in Rats by Poloxamer Gel Using Poloxamer 188 and Menthol

To improve the oral bioavailability of poorly water-soluble ibuprofen with poloxamer and menthol, the effects of menthol and poloxamer 188 on the aqueous solubility of ibuprofen were investigated. The dissolution and pharmacokinetic study of ibuprofen delivered by the ibuprofen-loaded preparations composed of poloxamer 188 and menthol were then performed. In the absence of poloxamer, the solubility of ibuprofen increased until the ratio of menthol to ibuprofen increased from 0:10 to 4:6 followed by an abrupt decrease in solubility above the ratio of 4:6, indicating that four parts menthol formed eutectic mixture with six parts ibuprofen. In the presence of poloxamer, the solutions with the same ratio of menthol to ibuprofen showed an abrupt increase in the solubility of ibuprofen. The poloxamer gel with menthol/ibuprofen ratio of 1:9 and higher than 15% poloxamer 188 showed the maximum solubility of ibuprofen, 1.2 mg/mL. The simultaneous addition of menthol and poloxamer 188 significantly improved the dissolution rates of ibuprofen from aqueous solution due to the ibuprofen solubility-improving effect of menthol in the presence of poloxamer. Furthermore, the ibuprofen-loaded preparation with menthol and poloxamer 188 gave significantly higher initial plasma concentrations, Cmax, and AUC of ibuprofen than did the preparation without menthol and poloxamer 188, indicating that the simultaneous addition of menthol and poloxamer 188 could improve the oral bioavailability of ibuprofen in rats. In modern pain management it is always desirable for the ibuprofen-loaded preparation with poloxamer 188 and menthol to show a rapid onset of action with a minimal phase of lag time to feel the decreased pain. From an industry point of view, it is more desirable for a formulation to be fast acting, easy to use, and cost effective. Thus, the ibuprofen-loaded preparation with poloxamer 188 and menthol was a more effective oral dosage form for poorly water-soluble ibuprofen.

Process optimization and characterization of poloxamer solid dispersions of a poorly water-soluble drug

The objective of the present investigation was to improve the dissolution rate of Rofecoxib (RXB), a poorly water-soluble drug by solid dispersion technique using a water-soluble carrier, Poloxamer 188 (PXM). The melting method was used to prepare solid dispersions. A 3(2) full factorial design approach was used for optimization wherein the temperature to which the melt-drug mixture cooled (X(1) ) and the drug-to-polymer ratio (X(2) ) were selected as independent variables and the time required for 90% drug dissolution (t(90)) was selected as the dependent variable. Multiple linear regression analysis revealed that for obtaining higher dissolution of RXB from PXM solid dispersions, a low level of X(1) and a high level of X(2) were suitable. The differential scanning calorimetry and x-ray diffraction studies demonstrated that enhanced dissolution of RXB from solid dispersion might be due to a decrease in the crystallinity of RXB and PXM and dissolution of RXB in molten PXM during solid dispersion preparation. In conclusion, dissolution enhancement of RXB was obtained by preparing its solid dispersions in PXM using melting technique. The use of a factorial design approach helped in identifying the critical factors in the preparation and formulation of solid dispersion.

Effect of flavors on the viscosity and gelling point of aqueous poloxamer solution

This study examined the effects of flavors, which are usually added to improve the appeal of pharmaceutical agents, on the viscosity and gelling point of 18% (w/w) aqueous poloxamer 407 solutions. Monoterpenes, esters, alcohols, aldehyde . ketones and lactone type flavors were examined. The concentrations of flavor ranged from 0.1 to 1.0% (w/w). After adding a flavor to the aqueous poloxamer 407 solution, the viscosity of the solution was measured using a Brookfield viscometer, and the gelling point was determined from the viscosity vs. temperature plot. The gelling point of the aqueous poloxamer 407 solution decreased with increasing concentration of flavors except for coumarin, vanillin and ethylvanillin. Thermal analysis with DSC showed an interaction between the flavors and poloxamer 407. These results suggest that the flavors bind to the hydrophilic end chains of poloxamer 407, which increases the viscosity, causing gelation at lower temperatures.

Delivery of 125I-cobrotoxin after intranasal administration to the brain: a microdialysis study in freely moving rats

In order to determine the contribution of intranasal (i.n.) administration to the uptake of large molecular weight (MW) substances into central nervous system (CNS), concentration in brain of the centrally acting polypeptide cobrotoxin (NT-I) versus time profiles were studied using dual-probe microdialysis in awake free-moving rats. NT-I, radiolabeled with sodium (125)I-Iodide ((125)I-NT-I), was administered at the dose of 105 microg/kg intravenously and intranasally in the same set of rat (n=15). The (125)I-NT-Inasal preparations were formulated with borneol/menthol eutectic mixture (+BMEM) as an absorption enhancer and without (-BMEM). After application, the dialysates sampled simultaneously from olfactory bulb and cerebellar nuclei were measured in a gamma-counter for radioactivity. The real concentrations of NT-I were recalculated by in vivo recoveries of microdialysis probes. The results showed that the area under the curve (AUC) value in cerebellar nuclei (2283.51+/-34.54 min ng/ml) following i.n. administration (+BMEM) was significantly larger than those (AUC(olfactory)=1141.92+/-26.42 min ng/ml; AUC(cerebellar)=1364.62+/-19.35 min ng/ml) after intravenous (i.v.) bolus, respectively. A prolonged time values to peak concentrations after i.n. application (+BMEM) were observed compared with those following i.v. administration. Also, following i.n. application (+BMEM) the measured time value to peak concentration in cerebellar nuclei (85 min) was statistically longer than that in olfactory bulb (75 min), which could be plausibly an indication for NT-I delivery into brain via nose-brain pathway in the presence of absorption enhancer. i.n. administration (-BMEM) had little or no ability of NT-I delivering into brain. In conclusion, i.n. administration (+BMEM) significantly enhanced brain transport of NT-I with uneven distribution in discrete regions of brain compared with i.v. administration. Additionally, multi-probe microdialysis technique should be considerably valuable in brain delivery studies.