Sustained relief of pain from osteosynthesis surgery of rib fracture by using biodegradable lidocaine-eluting nanofibrous membranes

Tri-Layered Doxycycline-, Collagen- and Bupivacaine-Loaded Poly(lactic-co-glycolic acid) Nanofibrous Scaffolds for Tendon Rupture Repair

Achilles tendon rupture is a severe injury, and its optimal therapy remains controversial. Tissue engineering scaffolds play a significant role in tendon healing and tissue regeneration. In this study, we developed tri-layered doxycycline/collagen/bupivacaine (DCB)-composite nanofibrous scaffolds to repair injured Achilles tendons. Doxycycline, collagen, and bupivacaine were integrated into poly(lactic-co-glycolic acid) (PLGA) nanofibrous membranes, layer by layer, using an electrospinning technique as healing promoters, a 3D scaffold, and painkillers, respectively. After spinning, the properties of the nanofibrous scaffolds were characterized. In vitro drug discharge behavior was also evaluated. Furthermore, the effectiveness of the DCB–PLGA-composite nanofibers in repairing ruptured Achilles tendons was investigated in an animal tendon model with histological analyses. The experimental results show that, compared to the pristine PLGA nanofibers, the biomolecule-loaded nanofibers exhibited smaller fiber size distribution and an enhanced hydrophilicity. The DCB-composite nanofibers provided a sustained release of doxycycline and bupivacaine for over 28 days in vivo. Additionally, Achilles tendons repaired using DCB-composite nanofibers exhibited a significantly higher maximum load-to-failure than normal tendons, suggesting that the biomolecule-incorporated nanofibers are promising scaffolds for repairing Achilles tendons.

Biodegradable Antimicrobial Agent/Analgesic/Bone Morphogenetic Protein-Loaded Nanofibrous Fixators for Bone Fracture Repair

Purpose

Postoperative infection and pain management are of great concern to orthopedic surgeons. Although there are several protocols available to deal with these aspects, they are fraught with complications, such as cartilage damage, cardiovascular and neurological intoxication, and systemic adverse responses. Therefore, it is necessary to develop safe and effective perioperative protocols. In the current study, antimicrobial agents/analgesics/growth factor-embedded biodegradable hybrid fixators (polycaprolactone fixator + poly[lactide-co-glycolide] sheath-core structured nanofibers) for bone fracture repair were designed.

Methods

The biodegradable hybrid fixators were fabricated using solution-extrusion three-dimensional printing and electrospinning. In vitro, the characteristics of the hybrid fixators were examined. Additionally, the release of the incorporated vancomycin, ceftazidime, lidocaine, and bone morphogenetic protein-2 (BMP-2) was evaluated. The in vivo efficacy including drug-eluting properties, fracture repair, and pain management of the biomolecule-loaded nanofibrous fixators was investigated in rabbit rib-fracture models.

Results

The nanofibrous fixators released vancomycin, ceftazidime, and lidocaine in a sustained manner under both in vitro and in vivo conditions and protected BMP-2 from burst release. The implantation of these hybrid fixators around the fractured rib significantly improved animal activities and bone union, indicating that the inclusion of analgesic in the fixator effectively reduced postsurgical pain and thereby helped in recovery.

Conclusion

The novel biomolecule-loaded nanofibrous hybrid fixators resulted in excellent therapeutic outcomes. These fixators may be effective in the repair of rib fractures in clinical settings and may help mitigate surgical complications, such as infection, nonunion, and intolerable postoperative pain.

Lidocaine-eluting endotracheal tube effectively attenuates intubation related airway response

Background

Lidocaine (LDC) is a local anesthetic widely used to relieve intubation-related airway responses. However, low drug concentration and short effective duration of LDC is inadequate to provide a satisfactory anesthetic effect on the surface of the airway. The present study sought to develop a LDC-delivery endotracheal tube (ETT) to achieve high local drug concentration and sustained drug release with the aim of attenuating an intubation-related airway response.

Methods

ETTs and polyvinyl chloride (PVC) discs were coated with different molecular weight (MW) poly lactic-co-glycolic acid (PLGA: 50/50; MW: 3,000, 6,000, and 10,000) loaded with LDC by airbrush spray. The morphology of LDC-eluting coatings was analyzed using scanning electron microscopy. In vitro drug release was determined by ultraviolet spectrophotometer. An in vivo study was performed to investigate the differences in plasma LDC concentration, intubation tolerance, and tracheal tissue injury in rabbits undergoing intubation of blank, LDC-spray, or LDC-coated ETTs.

Results

Approximate 5 mg/cm² coatings (containing 2.5 mg/cm² LDC) were deposited onto the PVC discs and ETTs. While even distribution and smooth surfaces were generated in PLGA3000 + LDC and PLGA6000 + LDC coatings, PLGA10000 + LDC formed uneven and gullied coatings. Burst release within the first 4 h and sustained release for at least 5 days was achieved in vitro in PLGA + LDC coatings and the in vivo study demonstrated higher plasma LDC concentration and longer drug release duration in LDC-coated ETTs compared with LDC-spray. LDC-coated ETTs significantly improved intubation tolerance in rabbits, as measured by less general anesthetic consumption and longer tube tolerance duration in contrast to blank ETTs with or without LDC spray. Histology assessment showed less mucosal edema area in the PLGA3000 + LDC and PLGA6000 + LDC groups compared to the control, LDC-spray, and PLGA10000 + LDC groups. Among the different MW PLGAs, PLGA6000 presented optimal morphological characteristics, drug release, and anesthetic effect.

Conclusions

ETTs coated with PLGA + LDC effectively attenuate an intubation-related airway response via increasing local drug concentration and extending drug action duration, which demonstrates a potential therapeutic benefit for patients undergoing intubation.

Sustained Release of Levobupivacaine, Lidocaine, and Acemetacin from Electrosprayed Microparticles: In Vitro and In Vivo Studies

In this study, we explored the release characteristics of analgesics, namely levobupivacaine, lidocaine, and acemetacin, from electrosprayed poly(D,L-lactide-co-glycolide) (PLGA) microparticles. The drug-loaded particles were prepared using electrospraying techniques and evaluated for their morphology, drug release kinetics, and pain relief activity. The morphology of the produced microparticles elucidated by scanning electron microscopy revealed that the optimal parameters for electrospraying were 9 kV, 1 mL/h, and 10 cm for voltage, flow rate, and travel distance, respectively. Fourier-transform infrared spectrometry indicated that the analgesics had been successfully incorporated into the PLGA microparticles. The analgesic-loaded microparticles possessed low toxicity against human fibroblasts and were able to sustainably elute levobupivacaine, lidocaine, and acemetacin in vitro. Furthermore, electrosprayed microparticles were found to release high levels of lidocaine and acemetacin (well over the minimum therapeutic concentrations) and levobupivacaine at the fracture site of rats for more than 28 days and 12 days, respectively. Analgesic-loaded microparticles demonstrated their effectiveness and sustained performance for pain relief in fracture injuries.

Lidocaine/ketorolac-loaded biodegradable nanofibrous anti-adhesive membranes that offer sustained pain relief for surgical wounds

The aim of this study was to develop and evaluate the effectiveness of biodegradable nanofibrous lidocaine/ketorolac-loaded anti-adhesion membranes to sustainably release analgesics on abdominal surgical wounds. The analgesic-eluting membranes with two polymer-to-drug ratios (6:1 and 4:1) were produced via an electrospinning technique. A high-performance liquid chromatography (HPLC) assay was employed to characterize the in vivo and in vitro release behaviors of the pharmaceuticals from the membranes. It was found that all biodegradable anti-adhesion nanofibers released effective concentrations of lidocaine and ketorolac for over 20 days post surgery. In addition, a transverse laparotomy was setup in a rat model for an in vivo assessment of activity of postoperative recovery. No tissue adhesion was observed at 2 weeks post surgery, demonstrating the potential anti-adhesion capability of the drug-eluting nanofibrous membrane. The postoperative activities were recorded for two groups of rats as follows: rats that did not have any membrane implanted (group A) and rats that had the analgesic-eluting membrane implanted (group B). Rats in group B exhibited faster recovery times than those in group A with regard to postoperative activities, confirming the pain relief effectiveness of the lidocaine- and ketorolac-loaded nanofibrous membranes. The experimental results suggested that the anti-adhesion nanofibrous membranes with sustainable elution of lidocaine and ketorolac are adequately effective and durable for the purposes of postoperative pain relief in rats.