Tamibarotene-Loaded PLGA Microspheres for Intratumoral Injection Administration: Preparation and Evaluation

Development of Intratumoral Drug Delivery Based Strategies for Antitumor Therapy

Research for tumor treatment with significant therapy effects and minimal side-effects has been widely carried over the past few decades. Different drug forms have received a lot of attention. However, systemic biodistribution induces efficacy and safety issues. Intratumoral delivery of agents might overcome these problems because of its abundant tumor accumulation and retention, thereby reducing side effects. Delivering hydrogels, nanoparticles, microneedles, and microspheres drug carriers directly to tumors can realize not only targeted tumor therapy but also low side-effects. Furthermore, intratumoral administration has been integrated with treatment strategies such as chemotherapy, enhancing radiotherapy, immunotherapy, phototherapy, magnetic fluid hyperthermia, and multimodal therapy. Some of these strategies are ongoing clinical trials or applied clinically. However, many barriers hinder it from being an ideal and widely used option, such as decreased drug penetration impeded by collagen fibers of a tumor, drug squeezed out by high density and high pressure, mature intratumoral injection technique. In this review, we systematically discuss intratumoral delivery of different drug carriers and current development of intratumoral therapy strategies.

The Effects of a Novel Curcumin Derivative Loaded Long-Circulating Solid Lipid Nanoparticle on the MHCC-97H Liver Cancer Cells and Pharmacokinetic Behavior

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Porous Core/Dense Shell PLA Microspheres Embedded with High Drug Loading of Bupivacaine Crystals for Injectable Prolonged Release

Objective of the study was to design an injectable microsphere preparation with high drug loading of bupivacaine for prolonged release and local anesthetic. PLA or PLGA was used as the biodegradable matrix material to fabricate microspheres with the o/w emulsification-solvent evaporation method. The characterization of bupivacaine microspheres was observed by SEM, DSC, and XRPD. The microsphere preparation and extended drug release, as well as the plasma drug concentration and sciatic nerve blockade after injection of the microsphere formulation to rats were investigated. High drug-loading microspheres of more than 70% were successfully obtained with extended drug release over 5 days in vitro depending on the type of matrix and the feed ratio of drug to polymer. SEM, DSC, and XRPD results verified a novel microsphere structure characterized as the porous core composed of PLA material and form II bupivacaine crystals and dense shell formed of PLA layer. The mechanism that bupivacaine was dissolved inside the microsphere and diffused across the dense shell was suggested for drug release in vitro. The optimized PLA microsphere formulation showed low and steady plasma drug concentration over 5 days and prolonged duration of sensory and motor blockade of sciatic nerve lasted more than 3 days. Results indicated that the porous core-shell structure of PLA microsphere formulation would provide enormous potential as an injectable depot for locally prolonged delivery of bupivacaine and control of postoperative pain.

Quaternary ammonium silane, calcium and phosphorus-loaded PLGA submicron particles against Enterococcus faecalis infection of teeth: An in vitro and in vivo study

Refractory root canal infection of human teeth is the primary cause of dental treatment failure. Enterococcus faecalis is the major cause of refractory root canal infection. In the present study, poly(D,L-lactic-co-glycolide) (PLGA) submicron particles were used as carriers to deliver an antimicrobial quaternary ammonium silane (code-named K21) as well as calcium and phosphorus elements. The release profiles, antibacterial ability against E. faecalis, extent of infiltration into dentinal tubules, biocompatibility and in vitro mineralization potential of the particles were investigated. In addition, the antimicrobial effects of the particles against E. faecalis infection were evaluated in vivo in the teeth of beagle dogs. The encapsulated components were released from the PLGA particles in a sustained-release manner. The particles also displayed good biocompatibility, in vitro mineralization ability and antibacterial activity against E. faecalis. The particles could be driven into dentinal tubules of dentin slices by ultrasonic activation and inhibited E. faecalis colonization. In the root canals of beagle dogs, PLGA submicron particles loaded with K21, calcium and phosphorus demonstrated strong preventive effects against E. faecalis infection. The system may be developed into a new intracanal disinfectant for root canal treatment.

Preparation and Evaluation of Irinotecan Poly(Lactic-co-Glycolic Acid) Nanoparticles for Enhanced Anti-tumor Therapy

Irinotecan (IRT), the pro-drug of SN-38, has exhibited potent cytotoxicity against various tumors. In order to enhance the anti-tumor effect of IRT, we prepared IRT-loaded PLGA nanoparticles (IRT-PLGA-NPs) by emulsion-solvent evaporation method. Firstly, IRT-PLGA-NPs were characterized through drug loading (DL), entrapment efficiency (EE), particle size, zeta potential, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). We next studied the in vitro release characteristics of IRT-PLGA-NPs. Finally, the pharmacokinetics and pharmacodynamics profiles of IRT-PLGA-NPs were investigated. The results revealed that IRT-PLGA-NPs were spherical with an average size of (169.97 ± 6.29) nm and its EE and DL were (52.22 ± 2.41)% and (4.75 ± 0.22)%, respectively. IRT-PLGA-NPs could continuously release drug for 14 days in vitro. In pharmacokinetics studies, for pro-drug IRT, the t_1/2β of IRT-PLGA-NPs was extended from 0.483 to 3.327 h compared with irinotecan solution (IRT-Sol), and for its active metabolite SN-38, the t_1/2β was extended from 1.889 to 4.811 h, which indicated that IRT-PLGA-NPs could prolong the retention times of both IRT and SN-38. The pharmacodynamics results revealed that the tumor doubling time, growth inhibition rate, and specific growth rate of IRT-PLGA-NPs were 2.13-, 1.30-, and 0.47-fold those of IRT-Sol, respectively, which demonstrated that IRT-PLGA-NPs could significantly inhibit the growth of tumor. In summary, IRT-PLGA-NPs, which exhibited excellent therapeutic effect against tumors, might be used as a potential carrier for tumor treatment in clinic.

Intratumoral Injection Administration of Irinotecan-Loaded Microspheres: In Vitro and In Vivo Evaluation

To reduce the toxic and side effects of intravenous chemotherapeutic drugs on the tumor-patients, the aims of this study were to design and study intratumor-administrated irinotecan-loaded PLGA microspheres (CPT-11-PLGA-MS) in vitro and in vivo according to the structure characteristics of CPT-11. PLGA microspheres containing irinotecan were prepared by emulsion solvent evaporation method and evaluated in terms of their morphology, particle size analysis, in vitro drug release, drug retention and leakage studies in vivo, and pharmacodynamics studies. The CPT-11-PLGA-MS were spherical with mean size of 9.29 ± 0.02 μm, and average encapsulation efficiency were measured of 77.97 ± 1.26% along with the average drug loading of 7.08 ± 0.11%. DSC results indicated that the drug existed in the phase of uncrystallization in the microspheres. The formulation of CPT-11-PLGA-MS could prolong the in vitro drug release to 16 days following Weibull equation. In CPT-11-PLGA-MS after intratumor injection administration was significantly improved. The results demonstrated that the slow-sustained release of CPT-11-PLGA-MS in tumor tissue after intratumor injection of microspheres can reduce the drug leakage to the circulation system, maintain the drug retention, and improve the therapeutic effect, which could become a promising drug delivery system for CPT-11 and could maintain the most effective concentration at the target site to maximum limit.