Current Drug Delivery - Volume 16, Issue 6, 2019

Background: The local anesthetic drugs, especially ropivacaine, were considered favorable analgesia for postoperative management because of their effective local pain relief and low adverse effects. However, the short half-life and the resulting in bolus doses lead to the indistinctive improvement of these drugs in postoperative pain relief. Therefore, the ropivacaine microspheres with sustained release and low initial burst release were anticipated. Methods: Three methods including oil in water (O/W), water in oil in water (W/O/W), and solid in oil in water (S/O/W) emulsion solvent evaporation method were used to optimize the ropivacaine loaded PLGA microspheres. The microspheres were evaluated both in vitro and in rats. The in vitro-in vivo correlation (IVIVC) was also investigated. Results: The microspheres prepared by O/W method showed more satisfactory properties and the microspheres used for evaluation were prepared by O/W method. The particle size, drug loading, encapsulation efficiency and burst release were 11.19±1.24 μm, 28.37±1.15%, 98.15±3.98%, and 10.96±5.37% for microspheres with PLGA of 12 kDa, and 6.64±0.61 μm, 19.62±0.89%, 92.74±4.21%, and 18.42±5.12% for microspheres with PLGA of 8 kDa, respectively. These microspheres were also injected into rats by subcutaneous, intramuscular and intraperitoneal route, respectively. It was indicated that the detectable concentration of ropivacaine could last for at least 20 days for both kinds of microspheres in spite of injection routes. The low burst releases at 1 d were also manifested in rats and they were 6.62%, 6.99%, 6.48% for the microspheres with PLGA of 12 kDa, and 4.72%, 4.33%, 4.48% for the microspheres with PLGA of 8 kDa by intraperitoneal, intramuscular and subcutaneous route, respectively. A linear relationship between the in vitro release and the in vivo adsorption of ropivacaine from microspheres was also established. Conclusion: The ropivacaine microspheres with sustained release and low burst release were acquired, which indicated that the postoperative pain relief might last longer and the side effects might get lower. Therefore, the ropivacaine microspheres prepared in this paper have great potential for clinical use.

Background: Olmesartan medoxomil (OLM) is a promising prodrug hydrolyzed to olmesartan (OL) during absorption from the gastrointestinal tract. OL is a selective angiotensin II receptor antagonist, with high drug resistance and low drug interaction. However, OLM has low solubility and low bioavailability. Therefore, it is extremely urgent to reduce the drug particle size to improve its biological bioavailability. Objective: The aim of the study was to improve the oral bioavailability of poorly water-soluble olmesartan medoxomil (OLM) by using different particle size-reduction strategies. Method: Raw drug material was micronized or nanosized by either jet or wet milling processes, respectively. The particle sizes of the prepared nanocrystals (100-300 nm) and microcrystals (0.5-16 μm) were characterized by DLS, SEM, and TEM techniques. Solid state characterization by XPRD and DSC was used to confirm the crystalline state of OLM after the milling processes. Results: We demonstrated that OLM nanocrystals enhanced solubility and dissolution in the non-sink condition in which high sensitivity was found in purified water. After 1 h, 65.4% of OLM was dissolved from nanocrystals, while microcrystals and OLMETEC® only showed 37.8% and 31.9% of drug dissolution, respectively. In the pharmacokinetic study using Beagle dogs, an increase in Cmax (#158;2 fold) and AUC (#158;1.6 fold) was observed after oral administration of OLM nanocrystals when compared to microcrystals and reference tablets, OLMETEC®. In contrast, OLM microcrystals failed to improve the oral bioavailability of the drugs. Conclusion: Particles size reduction to nano-scale by means of nanocrystals technology significantly increased in vitro dissolution rate and in vivo oral bioavailability of OLM.

Objective: In the present work, we report for the first time the therapeutic potential of talazoparib (BMN 673)-SLNs for the treatment of BRCA1 deficient Triple Negative Breast Cancer (TNBC). BMN 673-SLNs were produced by hot-homogenization technique and then characterized. Methods: The cytotoxic and apoptotic effects of BMN 673-SLNs compared with BMN 673 were determined on HCC1937BRCA1-/-, HCC1937-R resistant TNBC and MCF-10A control cell lines. BMN 673- SLNs were found to have reduced particle size (219.5 ± 1.45 nm) and thus more stable (-28.4 ± 2.52 mV) than BMN 673 (1652 ± 2.46 nm and -18.6 ± 0.45 mV) at 4°C. Results: In vitro cell line studies demonstrated that BMN 673-SLNs showed significant cytotoxic effects on HCC1937 (29.8%) and HCC1937-R cells (35.7%) at 10 nM for 12 days compared with BMN 673 (HCC1937 cells: 34.0% and HCC1937-R cells: 93.8% at 10 nM for 12 days) (p<0.05). Additionally, BMN 673-SLNs (40.1%) reduced the toxicity of BMN 673 (53.1%) on MCF-10A control cells thanks to unique physical properties. Conclusion: The apoptotic rates in the 10 nM BMN 673-SLNs treatment (88.78% and 85.56%) for 12 days were significantly higher than those in 10 nM BMN 673 (82.6% and 25.86%) for 12 days in HCC1937 and HCC1937-R cells, respectively (p<0.01). Furthermore, these effects were consistent with the findings of colony formation, wound healing and calcein accumulation analysis. In conclusion, the therapeutic potential of BMN 673-SLNs provides a promising chemotherapeutic strategy for the treatment of drugresistant TNBC.

Background: Enhancement of the bone regenerative capacity of the bone substitutes could be achieved by incorporating bioactive agents such as proteins, and different drugs. Simvastatin, an inhibitor of cholesterol synthesis, stimulates bone formation by enhancing the expression of Bone Morphogenetic Protein-2 (BMP-2) in osteoblasts. Objective: The objective of the study is to evaluate bone regeneration following simvastatin loaded nano-hydroxyapatite scaffold in the bone defect created on the femoral condyle of rabbits. Methods: Twelve adult, New Zealand white rabbits were used in the study. Twenty-four defects of size 5x8 mm were created on the lateral aspect of the femoral condyle. The defects were filled with either Nano-Hydroxyapatite (nHA) particles alone or nHA with Simvastatin (SIM). The condyles were retrieved after 8 weeks and analyzed using micro CT and histology. Results: The Bone Mineral Density (BMD) was significantly higher for the defects filled with SIM loaded nHA compared to the nHA site. Micro CT showed a significantly higher bone volume in the defects filled with Simvastatin loaded site compared to the control site. Quantitative analysis of the histologic sections also showed significantly higher bone volume in the defects filled with SIM loaded nHA (57.2±4.8) compared to nHA alone (50.1±5.5). Conclusion: Based on the results, it can be concluded that local delivery of simvastatin enhanced the bone regeneration in rabbit femoral condyle. Simvastatin could be used as an activator to enhance bone regeneration in bone defects along with hydroxyapatite ceramics.

Background: Fenofibrate (FNB) is an effective drug for the treatment of hypertriglyceridemia, hypercholesterolemia as well as mixed hyperlipidemia. However, due to its poor aqueous solubility, FNB has the problem of poor oral absorption followed by low bioavailability. Objective: The aim of this research was to construct FNB amorphous solid dispersion employing PVP VA64 as the carrier by hot-melt extrusion method, in order to improve the oral bioavailability. Additionally, the cell transport experiment was conducted to further investigate the mechanism of promoted osmotic absorption. Methods: The physical state of the obtained solid dispersion was characterized using SEM, DSC and XRD. Besides, in vitro Caco-2 cells were used to evaluate the cytotoxicity of the carrier and mimic gastrointestinal drug permeation. At last, in vitro dissolution test and in vivo bioavailability study were also carried out. Results: The prepared FNB solid dispersion was found to be an amorphous state after hot-melt extrusion process. In vitro cytotoxicity test on Caco-2 cells confirmed the excellent biocompatibility of the carrier PVP VA64. Besides, transwell cell transport assay and in vitro dissolution test revealed that FNB released from amorphous solid dispersion was equipped with an improved transmembrane transport and dissolution rate. Moreover, pharmacokinetic study in beagle dogs showed that comparing with commercial micronized product Lipanthyl®, the oral bioavailability of FNB solid dispersion was significantly enhanced (2.45 fold). Conclusion: In conclusion, PVP VA64 can be regarded as a promising polymer to enhance the bioavailability of poorly water-soluble drugs such as FNB processed by hot-melt extrusion. Besides, investigations on the mechanism of the enhanced penetration are expected to lay a foundation on the subsequent development of effective and practical solid dispersion.

Objective: The aim of the present study was to design an efficient delivery system with an anticipated swelling and drug release properties for a prolonged drug release as well as to target colon for various hydrophilic drugs. Method: For this purpose, the pH-responsive hydrogel comprising a combination of Eudragit and acrylic acid was formed. The hydrogels were characterized for spectral (FTIR), thermal (TGA/DSC), structural (XRD), and morphological (SEM) investigations. Oral tolerability was assessed in rabbits for biocompatibility and oral use of the prepared hydrogels. Results: The results showed that an increased incorporation of Eudragit and cross-linking agent retorted the swelling, drug loading, and drug release properties at both acid (pH 1.2) and basic pH (pH 6.8 and 7.4) , while acrylic acid presented the inverse results. The oral tolerability and toxicity studies depicted that the developed hydrogels were safe up to 3800 mg/kg body weight and caused no hematological or histopathological changes when compared with the control group. Conclusion: Therefore, the newly developed formulations presented adequate swelling, drug loading, release behavior, and biocompatibility properties and thus can be used as a promising tool for the colonic delivery of various hydrophilic drugs.

Background: In the field of bone tissue engineering, there has been an increasing interest in biomedical materials with both high angiogenic ability and osteogenic ability. Among various osteogenesis materials, bioactive borosilicate and borate glass scaffolds possess suitable degradation rate and mechanical strength, thus drawing many scholars’ interests and attention. Objective: In this study, we fabricated bioactive glass scaffolds composed of borosilicate 2B6Sr using the Template-Method and incorporated Dimethyloxalylglycine (DMOG), a small-molecule angiogenic drug possessing good angiogenic ability, to improve bone regeneration. Methods: The in-vitro studies showed that porous borosilicate bioactive glass scaffolds released slowly, a steady amount of DMOG and stimulated the proliferation and osteogenic differentiation of human bone marrow stromal cells hBMSCs. Results: In-vivo studies showed that the borosilicate bioactive glass scaffolds could significantly promote new bone formation and neovascularization in rats’ calvarial bone defects. Conclusion: These results indicated that DMOG-incorporated bioactive glass scaffold is a successful compound with excellent angiogenesis-osteogenesis ability, which has favorable clinical prospects.

Background: A transdermal patch for delivery of Levonorgestrel (LNG) can be used for long-acting contraception. Objective: In this study, we designed and characterized a patch made of nonwoven electrospun microfibers comprised of Polycaprolactone (PCL) encapsulating LNG for slow release in a mineral oil matrix. Methods and Results: Scanning electron microscopy showed uniform, randomly oriented PCL fibers with large interconnected voids filled with mineral oil. Thermogravimetric analysis indicated that LNG loaded into PCL fibers had thermal stability up to ~200°C. Differential Scanning Calorimetry suggested that LNG was dispersed in the electrospun fibers without interaction between the LNG and PCL, and without formation of drug crystals. Fourier Transform Infrared spectroscopy and X-ray diffraction results further supported the conclusion that there was no chemical drug–polymer interaction in LNGloaded fibers. Effective in vitro flux (i) from patches into mineral oil was 1.9 μgcm-2h-1, (ii) from mineral oil across porcine skin was 4.6 μgcm-2h-1 and (iii) from patches across porcine skin was 1.7 μgcm- 2h-1, indicating that transdermal delivery rate was controlled by a combination of the patch and the skin. Conclusion: The LNG-loaded patches demonstrated steady delivery of LNG across skin for up to 5 days in vitro. With additional development, LNG-loaded electrospun PCL patches could be used for long-acting contraception.