Preparation and in vitro/in vivo evaluation of uniform-sized Goserelin-loaded sustained release microspheres.

Sustained release microspheres loaded with goserelin are regarded as a promising candidate for treating prostate cancer and other sex hormone diseases. However, their widespread adoption has been hindered by issues such as wide particle size distribution and unstable release characteristics. To address these challenges, we employed a combination of the solid-in-oil-in-water microspheres preparation approach (S/O/W) and innovative premix membrane emulsification technology and deeply investigated the effects of four key parameters on the loaded performance of microspheres and the microscopic mechanisms behind them. With this approach, we successfully produced goserelin-loaded sustained release microspheres of narrow particle size distribution (Span 0.642), remarkable encapsulation efficiency (DL = 4.23 %, EE = 93.98 %), low initial burst release (about 0.50 % within 2 h), and compatibility with small injection needles (23-G, inner diameter 0.33 mm, outer diameter 0.64 mm, maximal force 59 N). In the animal model(administered dose, 2.4 mg·Kg-1), goserelin long-acting sustained release microspheres sustained release for over 32 days, maintaining effective concentrations above 2 ng·mL-1, and effectively reduced serum testosterone concentrations to castration levels (<1.0 ng·mL-1) by day 4, maintaining this inhibition for up to 21 days, exhibiting comparable efficacy to the positive control group. In vivo release kinetics analysis revealed that goserelin-loaded sustained release microspheres exhibited a release pattern dominated by diffusion with corrosion assistance in vivo. In summary, the systematic and comprehensive evaluation of uniform-sized goserelin-loaded sustained release microspheres has highlighted their excellent translational potential, and the study herein may provide new strategies and ideas for the development of microsphere dosage forms.

Development of a method for determination of progesterone sustained-release formulation in Beagle dog plasma and its pharmacokinetic study / 药学学报

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to determine the plasma concentration of progesterone in Beagle dogs, and apply it to the study of the pharmacokinetics of progesterone sustained-release formulation in Beagle dogs. The plasma samples were processed by protein precipitation method and megestrol acetate was used as an internal standard (IS). The quantitation analysis was performed using multiple-reaction monitoring (MRM) mode at the specific ion transitions of m/z 315.2→97.0 for progesterone and m/z 385.2→267.1 for megestrol acetate (IS) under the positive ion condition. Male Beagle dogs were injected intramuscularly with progesterone sustained-release microspheres and the plasma samples were collected at different time points after administration. The relevant pharmacokinetic parameters were calculated by WinNonlin 8.1 software. A good linearity over the range of 0.1-500.0 ng·mL-1 was yielded by this method. The intra- and inter-day precision (RSD) were all less than 13.25% and the accuracy (RE) was within 8.92%. Stability test showed that progesterone in dog plasma was stable at room temperature for 12 h, up to 60 days at -20 ℃ and after three cycles of freeze-thaw. The recovery of it ranged from 71.43%-77.97%. After intramuscular injection of progesterone sustained-release microspheres in Beagle dogs, tmax was 19.00 ± 25.36 h, Cmax was 137.72 ± 11.59 ng·mL-1, t1/2 was 83.83 ± 26.43 h. The drug was released continuously in vivo and in a continuous absorption process for many times with good sustained-release effect. The method developed in this study is sensitive, rapid and stable. It is suitable for the determination of progesterone plasma concentration in Beagle dogs, and can be applied to the preclinical pharmacokinetic study of progesterone-related formulations. The animal experiment scheme of this study was approved by the Animal Ethics Committee of the Academy of Military Medical Sciences.

Rifapentine Polylactic Acid Sustained-Release Microsphere Complex for Spinal Tuberculosis Therapy: Preparation, in vitro and in vivo Studies.

PURPOSE: Spinal tuberculosis has been a common clinical extrapulmonary tuberculosis in recent years. The general anti-tuberculosis drug treatment cycle is long, with unsatisfactory efficacy. This study focused on the preparation and evaluation of rifapentine polylactic acid sustained-release microsphere complex for spinal tuberculosis therapy. METHODS: Rifapentine polylactic acid sustained-release microspheres (RPSMs) were prepared through the double emulsion solvent evaporation method, and RPSMs were combined with hydroxyapatite/ß-tricalcium phosphate (HA/ß-TCP) composite material to obtain drug-loaded, sustained-release complex. We evaluated the complex for dynamics of drug release and osteogenic ability using in vitro release test, alkaline phosphatase and alizarin red staining, real-time PCR and Western blot. A rabbit model of a spinal tuberculosis defect was established and repaired using HA/ß-TCP or complex. The ability of anti-tuberculosis and tissue repair effects of the complex were evaluated through in vivo experiments. RESULTS: The complex constructed of RPSMs and HA/ß-TCP demonstrated a long drug release time, with no significant inhibition of cell osteogenic differentiation in vitro experiments. Postoperative macroscopic observation, immunohistochemical staining and Nilsson histological scores showed that the complex has good effects on the tissue repair. Moreover, the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), important indexes of inflammation, decreased to normal levels in the complex group. CONCLUSION: In vitro and in vivo experiments demonstrated that the complex constructed of RPSMs and HA/ß-TCP effectively treated spinal tuberculosis. Therefore, the complex represents a promising approach for the treatment of spinal tuberculosis.

Development and in vitro characterization of rifapentine microsphere-loaded bone implants: a sustained drug delivery system.

BACKGROUND: This study aimed to develop and evaluate a sustained drug delivery system for the treatment of osteoarticular tuberculosis (TB) to address the issues surrounding low drug concentration in lesions and bone defects or nonunion after debridement. METHODS: The effects of rifapentine on the proliferation and cell cycle of bone marrow mesenchymal stem cells (BMSCs) were evaluated by Cell Counting Kit-8 (CCK-8) and flow cytometry. Rifapentine polylactic acid (PLA) sustained-release microspheres (RPSMs) were prepared through the double emulsion solvent evaporation method and investigated the antibacterial activity in vitro. In this study, two sustained drug delivery systems were prepared by integrating RPSMs and BMSCs into hydroxyapatite/ß-tricalcium phosphate (HA/ß-TCP) or allogeneic bone. We evaluated these drug delivery systems for dynamics of drug release and osteogenic ability by in vitro release test, alkaline phosphatase (ALP) and alizarin red staining, and real-time PCR. RESULTS: The results showed that rifapentine concentrations up to 45.0 µg/mL had no effect on cell proliferation and cell cycle. The encapsulation and drug loading efficiency of the fabricated RPSMs were 78.11%±1.16% and 35.57%±0.85%, respectively. The RPSMs had uniform particle size distribution and a long-term anti-bacterium effect. The HA/ß-TCP-implanted drug delivery system was found to be more effective in reducing the burst release and having a longer duration of sustained release and retention compared to allogeneic bone. The ALP and alizarin red staining and real-time PCR results showed that it had excellent osteoconductive and osteoinductive properties. CONCLUSIONS: In conclusion, the sustained drug delivery system with HA/ß-TCP as scaffold material represents a potential new strategy for TB infections and bone defects.

Stromal vascular fraction cells plus sustained release VEGF/Ang-1-PLGA microspheres improve fat graft survival in mice.

Autologous fat transplantation is increasingly applied in plastic and reconstructive surgery. Stromal vascular fraction cells (SVFs) combined with angiogenic factors, such as VEGF (vascular endothelial growth factor A) and Ang-1 (angiogenin-1), can improve angiogenesis, which is a critical factor for graft survival. However, direct transplant with such a mixture is insufficient owing to the short half-life of angiogenic factors. In this study, we evaluated whether a double sustained release system of VEGF/ANG-1-PLGA (poly (lactic-co-glycolic acid)) microspheres plus SVFs can improve angiogenesis and graft survival after autologous fat transplantation. VEGF/ANG-1-PLGA-sustained release microspheres were fabricated by a modified double emulsion-solvent evaporation technique. Human aspirated fat was mixed with SVF suspension plus VEGF/ANG-1 sustained release microspheres (Group C), SVF suspension (Group B) alone, or Dulbecco's modified Eagle's medium as the control (Group A). Eighteen immunocompromised nude mice were injected with these three mixtures subcutaneously at random positions. After 8 weeks, the mean volume of grafts was greater in the SVFs plus VEGF/ANG-1-PLGA group than in the control and SVFs groups (1.08 ± 0.069 ml vs. 0.62 ± 0.036 ml, and 0.83 ± 0.059 ml, respectively). Histological assessments showed that lower fibrosis, but greater microvascular density in the SVFs plus VEGF/ANG-1-PLGA group than in the other groups, though the SVFs group also had an appropriate capillary density and reduced fibrosis. Our findings indicate that SVFs plus VEGF/ANG-1-PLGA-sustained release microspheres can improve angiogenesis and graft survival after autologous fat transplantation.

[Research progress of growth factor sustained-release microspheres in fat transplantation].

Objective: To review the research progress of growth factor sustained-release microspheres in fat transplantation. Methods: The recently published 1iterature at home and abroad related the growth factor sustained-release microspheres in fat transplantation was reviewed and analyzed. Results: The sustained-release microsphere carrier materials include natural polymer materials and synthetic polymer materials.The sustained-release complexes of different microsphere materials with different growth factors can promote the vascularization of transplanted fat in a timely manner, improve the survival rate of grafts, and reduce the incidence of complications such as liquefaction, calcification, and necrosis. Conclusion: The growth factor sustained-release microspheres have the characteristics of persistence and controllability, which is a research hotspot in the field of fat transplantation and has broad application prospects.

Drug Release Characteristics and Tissue Distribution of Rifapentine Polylactic Acid Sustained-Release Microspheres in Rabbits after Paravertebral Implantation.

BACKGROUND: Rates of drug-resistant tuberculosis (TB) and TB associated with human immunodeficiency virus (HIV) infection have increased dramatically, intensifying challenges in TB control. New formulations of TB treatment drugs that control drug release and increase local drug concentrations will have a significant impact on mitigating the toxic side effects and increasing the clinical efficacy of anti-TB drugs. OBJECTIVES: The aim was to observe the sustained release characteristics of rifapentine polylactic acid sustained-release microspheres in vivo and the accumulation of rifapentine in other tissues following paravertebral implantation. METHODS: This study is a basic animal experimental study that began on July 17, 2014 in the Fifth Affiliated hospital of Xinjiang Medical University. One hundred and eight New Zealand white rabbits (weighing 2.8 - 3.0 kg, male and female, China) were randomly divided into three groups of 36 rabbits each. Blood and tissue samples from the liver, lungs, kidneys, vertebrae, and paravertebral muscle were collected at different time points post-surgery. High performance liquid chromatography (HPLC) analysis with a biological internal standard was used to determine the drug concentrations in samples. RESULTS: In group A, no significant differences in rifapentine concentrations in the liver were detected between any two time points (P > 0.05). However, the differences in rifapentine concentrations between day 10 and day 21 were statistically significant (P < 0.05); for days 21, 35, 46, and 60, the differences in rifapentine concentrations between two sequential time points were not statistically significant (P > 0.05). In group B, the differences in rifapentine concentration between days 3 and 10 in vertebral bone and in paravertebral muscles were statistically significant (P < 0.05). Rifapentine was detected in the vertebral bone tissue in the group C animals. The rifapentine concentrations between two sequential time points were statistically significant (P < 0.05). Rifapentine could not be detected in the paravertebral muscles 46 days after the operation. The differences in rifapentine concentrations between two sequential time points among days 3, 10, 21, and 35 were statistically significant (P < 0.05). CONCLUSIONS: After paravertebral implantation of rifapentine polylactic acid sustained-release microspheres, the concentration of rifapentine in local vertebral bone tissues was maintained above the TB minimum inhibitory concentration for up to 60 days with no apparent accumulation of the drug in other tissues.

Characterization of unsaturated fatty acid sustained-release microspheres for long-term algal inhibition.

The unsaturated fatty acid (linoleic acid) sustained-release microspheres were prepared with linoleic acid (LA) using alginate-chitosan microcapsule technology. These LA sustained-release microspheres had a high encapsulation efficiency (up to 62%) tested by high performance liquid chromatography with a photo diode array. The dry microspheres were characterized by a scanning electron microscope, X-ray diffraction measurement, dynamic thermogravimetric analysis and Fourier transform infrared spectral analysis. The results of characterization showed that the microspheres had good thermal stability (decomposition temperature of 236°C), stable and temperature independent release properties (release time of more than 40 d). Compared to direct dosing of LA, LA sustained-released microspheres could inhibit Microcystis aeruginosa growth to the non-growth state. The results of this study suggested that the LA sustained-release microspheres may be a potential candidate for algal inhibition.

Preparation of donepezil sustained release microspheres and pharmacokinetic research in rabbits / 中国药学杂志

OBJECTIVE: To prepare and evaluate donepezil sustained-release microspheres by ultrasound technique. METHODS: Preparation technology of donepezil biodegradable microspheres by ultrasound technique was established and optimized. In vitro evaluation of donepezil microspheres was carried out. The pharmacokinetics of donepezil microspheres was investigated by LC-MS/MS after subcutaneous injection in rabbits at a dose of 30.0 mg · kg. RESULTS: Donepezil microspheres with drug loading of 12.1% and mean particle size between 40 to 130 μm were successfully prepared by ultrasound technique. The donepezil microspheres displayed a one-month sustained-release character in vitro. The pharmacokinetic parameters were as follows: pmax 40.63 μg · L-1, tmax 2.47 d, MRT 14.81 d, and AUC0→∞ 646.96 μg · d · L-1. CONCLUSION: Ultrasound technique is successfully applied in the preparation of donepezil sustained-release microspheres.

Pharmcokinetic study of cyclosporin A in rabbit eyes by HPLC / 西安交通大学学报(医学版)

Objective To study the pharmacokinetic characters of cyclosporin A(CsA) in aqueous humor in rabbit after implanting different dosages of CsA in eyes and to provide a theoretical basis for the treatment of after cataract. Methods ECCE was performed in all rabbit eyes. CsA-MS was injected into the anterior chamber and the capsular bag in left eyes as expression group and MS was given in the same way in right eyes as control group. The concentration of CsA in the aqueous humor was monitored with high-performance liquid chromatogram. The follow-up period was 4 weeks. The samples were separated on a C18 column at 60℃ and detected at 210nm. The mobile phase was acetonitrile-water (67∶33). Results The correlation analysis showed a positive correlation within the range of 0.13-1.25mg/L (r=0.9951) and the detection limit was 0.13mg/L. The accuracy was 95.91% and the inter-day and intro-day precision was less than 5%. CsA in aqueous humor sustained a high concentration within 2 weeks. There were no significant differences in t1/2Ka and CL between the two dosage groups. AUC and Cmax increased in a dose-dependent manner. Conclusion The sustain-released CsA ophthalmic gels provided significant ocular bioavailability in rabbit eyes and they can reach the therapeutic dose in order to inhibit after cataract.