Thermosensitive Pluronic hydrogel: prolonged injectable formulation for drug abuse

A thermo-responsive chemically crosslinked long-term-release chitosan hydrogel system increases the efficiency of synergy chemo-immunotherapy in treating brain tumors

Glioblastoma multiforme (GBM) is an aggressive and common brain tumor. The blood-brain barrier prevents several treatments from reaching the tumor. This study proposes a Chemo-Immunotherapy synergy treatment chemically crosslinked hydrogel system that is injected into the tumor to treat GBM. The strategy uses doxorubicin and BMS-1 with a thermo-responsive and chemically crosslinked hydrogel for extended drug release into the affected area. The hydrogels are produced by mixing with Chitosan (Chi), modified Pluronic F-127 (PF-127) with aldehyde end group and doxorubicin and then chemically crosslinking the aldehyde and amine bonds to increase the drug retention time. PF-127-CHO/Chi, which gels at body temperatures and chemically crosslinks between PF-127-CHO and Chitosan, increases the time that the drug remains in the affected area and prevents the hydrogel from swelling and compressing surrounding tissue. The drug is released from the chemically crosslinked hydrogels, prevents tumor progression and increases survival for subjects with GBM tumors. The Synergy Chemo-Immunotherapy also allows more efficient treatment of GBM than chemotherapy. The PF-127-CHO/Chi DOX and BMS-1 group have a tumor that is 43 times smaller than the untreated group. These results show that the proposed chemically crosslinking hydrogel is an efficient intratumoral delivery platform for the treatment of tumors.

Temperature-sensitive hydrogel releasing pectolinarin facilitate scarless wound healing

The dressing that promotes scarless healing is essential for both normal function and aesthetics after a wound. With a deeper understanding of the mechanisms involved in scar formation during the wound healing process, the ideal dressing becomes clearer and more promising. For instance, the yes-associated transcriptional regulator (YAP) has been extensively studied as a key gene involved in regulating scar formation. However, there has been limited attention given to pectolinarin, a natural flavonoid that may exhibit strong binding affinity to YAP, in the context of scarless healing. In this study, we successfully developed a temperature-sensitive Pluronic@F-127 hydrogel as a platform for delivering pectolinarin to promote scarless wound healing. The bioactive pectolinarin was released from the hydrogel, effectively enhancing endothelial cell migration, proliferation and the expression of angiogenesis-related genes. Additionally, a concentration of 20 μg/mL of pectolinarin demonstrated remarkable antioxidant ability, capable of counteracting the detrimental effects of reactive oxygen species (ROS). Our results from rat wound healing models demonstrated that the hydrogel accelerated wound healing, promoting re-epithelialization and facilitating skin appendage regeneration. Furthermore, we discovered that a concentration of 50 μg/mL of pectolinarin incorporated to the hydrogel exhibited the most favourable outcomes in terms of promoting wound healing and minimizing scar formation. Overall, our study highlights that the significant potential of locally released pectolinarin might substantially inhibit YAP and promoting scarless wound healing.

A novel sprayable thermosensitive hydrogel coupled with zinc modified metformin promotes the healing of skin wound

A novel sprayable adhesive is established (ZnMet-PF127) by the combination of a thermosensitive hydrogel (Pluronic F127, PF127) and a coordination complex of zinc and metformin (ZnMet). Here we demonstrate that ZnMet-PF127 potently promotes the healing of traumatic skin defect and burn skin injury by promoting cell proliferation, angiogenesis, collagen formation. Furthermore, we find that ZnMet could inhibit reactive oxygen species (ROS) production through activation of autophagy, thereby protecting cell from oxidative stress induced damage and promoting healing of skin wound. ZnMet complex exerts better effects on promoting skin wound healing than ZnCl₂ or metformin alone. ZnMet complex also displays excellent antibacterial activity against Staphylococcus aureus or Escherichia coli, which could reduce the incidence of skin wound infections. Collectively, we demonstrate that sprayable PF127 could be used as a new drug delivery system for treatment of skin injury. The advantages of this sprayable system are obvious: (1) It is convenient to use; (2) The hydrogel can cover irregular skin defect sites evenly in a liquid state. In combination with this system, we establish a novel sprayable adhesive (ZnMet-PF127) and demonstrate that it is a potential clinical treatment for traumatic skin defect and burn skin injury.

Microneedles Assisted Controlled and Improved Transdermal Delivery of High Molecular Drugs via Insitu Forming Depot Thermoresponsive Poloxamers Gels in Skin Microchannels

Skin considered as an attractive route for variety of drug molecules administration. However it proved to be the main physical barrier for drug flux owing to their poor permeability and low bioavailability across stratum corneum layer. In current study novel approach has been used to enhance transdermal delivery via microporation through combination of poloxamers gels and microneedles arrays. The phase transition of poloxamers at various concentrations from sol-gel was evaluated using AR2000 rheometer to confirm microneedles-assisted insitu forming depots. Temperature test confirmed gelation between 32-37 °C. Curcumin was loaded in poloxamer formulations at variable concentrations and its effect showed reduction in critical gelation temperature (CGT) owing to its hydrophobic nature. Microneedles (MNs) arrays (600 µm) prepared from Gantrez S-97, PEG 10000 and Gelatin B using (19 × 19) laser-engineered silicone micromoulds showed high mechanical stability investigated via Texture analyzer. From insitu dissolution profile Gelatin 15% w/w based MNs displayed quicker dissolution rate in comparison to PG10000. VivoSight® OCT scanner and dye tracking confirmed that PG10000 MNs arrays pierced SC layer, infiltrate the epidermis and goes to dermis layer. From invitro permeation, it was concluded that 20% w/w PF127^® gel formulations containing (0.1% and 0.3%) curcumin displayed high curcumin permeation for comparatively longer time through microporated skin samples in comparison to non-microporated skin. The curcumin distribution in skin tissues with higher florescence intensity was noted in MNs treated skin samples by confocal microscopy. FTIR confirmed the structure formation of fabricated MNs, while TGA showed dry, brittle and rigid nature of Gelatin MNs.

Human Umbilical Cord Mesenchymal Stem Cells Encapsulated with Pluronic F-127 Enhance the Regeneration and Angiogenesis of Thin Endometrium in Rat via Local IL-1β Stimulation

Thin endometrium (< 7 mm) could cause low clinical pregnancy, reduced live birth, increased spontaneous abortion, and decreased birth weight. However, the treatments for thin endometrium have not been well developed. In this study, we aim to determine the role of Pluronic F-127 (PF-127) encapsulation of human umbilical cord mesenchymal stem cells (hUC-MSCs) in the regeneration of thin endometrium and its underlying mechanism. Thin endometrium rat model was created by infusion of 95% ethanol. Thin endometrium modeled rat uterus were treated with saline, hUC-MSCs, PF-127, or hUC-MSCs plus PF-127 separately. Regenerated rat uterus was measured for gene expression levels of angiogenesis factors and histological morphology. Angiogenesis capacity of interleukin-1 beta (IL-1β)-primed hUC-MSCs was monitored via quantitative polymerase chain reaction (q-PCR), Luminex assay, and tube formation assay. Decreased endometrium thickness and gland number and increased inflammatory factor IL-1β were achieved in the thin endometrium rat model. Embedding of hUC-MSCs with PF-127 could prolong the hUC-MSCs retaining, which could further enhance endometrium thickness and gland number in the thin endometrium rat model via increasing angiogenesis capacity. Conditional medium derived from IL-1β-primed hUC-MSCs increased the concentration of angiogenesis factors (basic fibroblast growth factor (bFGF), vascular endothelial growth factors (VEGF), and hepatocyte growth factor (HGF)). Improvement in the thickness, number of glands, and newly generated blood vessels could be achieved by uterus endometrium treatment with PF-127 and hUC-MSCs transplantation. Local IL-1β stimulation-primed hUC-MSCs promoted the release of angiogenesis factors and may play a vital role on thin endometrium regeneration.

An injectable thermosensitive hydrogel loading with theranostic nanoprobe for synergetic chemo-photothermal therapy of multidrug-resistant hepatocellular carcinoma

Multi-drug resistance (MDR) is a complicated cellular defense mechanism for tumor cells to resist chemotherapy drugs, which is also the main cause of chemotherapy failure. In this study, we used...

Green Synthesis of Thermo-Responsive Hydrogel from Oil Palm Empty Fruit Bunches Cellulose for Sustained Drug Delivery

Drug delivery is a difficult task in the field of dermal therapeutics, particularly in the treatment of burns, wounds, and skin diseases. Conventional drug delivery mediums have some limitations, including poor retention on skin/wound, inconvenience in administration, and uncontrolled drug release profile. Hydrogels able to absorb large amount of water and give a spontaneous response to stimuli imposed on them are an attractive solution to overcome the limitations of conventional drug delivery media. The objective of this study is to explore a green synthesis method for the development of thermo-responsive cellulose hydrogel using cellulose extracted from oil palm empty fruit bunches (OPEFB). A cold method was employed to prepare thermo-responsive cellulose hydrogels by incorporating OPEFB-extracted cellulose and Pluronic F127 (PF127) polymer. The performance of the synthesized thermo-responsive cellulose hydrogels were evaluated in terms of their swelling ratio, percentage of degradation, and in-vitro silver sulfadiazine (SSD) drug release. H8 thermo-responsive cellulose hydrogel with 20 w/v% PF127 and 3 w/v% OPEFB extracted cellulose content was the best formulation, given its high storage modulus and complex viscosity (81 kPa and 9.6 kPa.s, respectively), high swelling ratio (4.22 ± 0.70), and low degradation rate (31.3 ± 5.9%), in addition to high t50% value of 24 h in SSD in-vitro drug release to accomplish sustained drug release. The exploration of thermo-responsive cellulose hydrogel from OPEFB would promote cost-effective and sustainable drug delivery system with using abundantly available agricultural biomass.

Thermosensitive Gels Used to Improve Microneedle-Assisted Transdermal Delivery of Naltrexone

Transdermal delivery of naltrexone (NTX) can be enhanced using microneedles, although micropores generated this way can reseal by 48 h in humans, which prevents further drug delivery from a formulation. Poloxamer 407 (P407) is a thermosensitive polymer that may extend microneedle-assisted NTX delivery time by creating an in situ gel depot in the skin. We characterized gelation temperature, drug release, and permeation of P407 gels containing 7% NTX-HCl. To investigate microneedle effects on NTX-HCl permeation, porcine skin was treated with microneedles (600 or 750 μm length), creating 50 or 100 micropores. The formulations were removed from the skin at 48 h to simulate the effect of micropores resealing in vivo, when drug delivery is blunted. Gelation temperature increased slightly with addition of NTX-HCl. In vitro NTX-HCl release from P407 formulations demonstrated first order release kinetics. Microneedle treatment enhanced NTX-HCl permeation both from aqueous solution controls and P407 gels. Steady-state flux was overall lower in the P407 conditions compared to the aqueous solution, though ratios of AUCs before and after gel removal demonstrate that P407 gels provide more sustained release even after gel removal. This may be beneficial for reducing the required application frequency of microneedles for ongoing treatment.

Thermosensitive hydrogels for local delivery of 5-fluorouracil as neoadjuvant or adjuvant therapy in colorectal cancer

Spurred by high risk for local tumor recurrence and non-specific toxicity of systemic chemotherapy, clinicians have recently granted a growing interest to locoregional therapeutic strategies. In this perspective, we recently developed a multipurpose thermosensitive hydrogel based on reversible thermogelling properties of poloxamers P407 and P188, a bioadhesive excipient and antineoplastic effect of 5-fluorouracil (5-FU) for the local treatment of colorectal cancer (CRC) in ectopic CT26 murine models. Antitumor efficacy was assessed in mice following intratumoral (IT) injection mimicking neoadjuvant therapy and subcutaneous (SC) application after tumor excision simulating adjuvant therapy. Rheological characterization disclosed that P407/P188/alginate 20/2/1% w/v thermosensitive hydrogel is an injectable free-flowing solution at ambient temperature that undergoes a SOL-GEL transition at 26.0 °C ± 0.6 °C and thereby forms in situ a non-flowing gel at physiological temperature. The generated gel presented an elastic behavior and responded according to a shear-thinning fluid upon shear rate. Although delayed by the addition of alginate 1% w/v, 5-FU is released mainly by diffusion mechanism. The local delivery of 5-FU from P407/P188/alginate/5-FU 20/2/1/0.5% w/v hydrogel in the preclinical tumor models led to a significant tumor growth delay. These results demonstrated that poloxamer-based thermosensitive hydrogels provide a simple and efficient means for local chemotherapeutics delivery.

Levofloxacin-loaded naturally occurring monoterpene-based nanoemulgel: a feasible efficient system to circumvent MRSA ocular infections

Staphylococcus aureus is a leading cause of ocular keratitis worldwide, and the upsurge of Methicillin-resistant Staphylococcus Aureus (MRSA) strains necessitated the development of new antimicrobial agents. D-limonene is the major constituent of oil extracted from citrus peel, which has been utilized for its gastroprotective, antifungal, antitumor, and antibacterial effects. The present study aimed to develop an effective in-situ ocular limonene-based nanoemulgel to enhance the efficacy of fluoroquinolones against MRSA associated ocular biofilm infection. The nanoemulsion composed of limonene, Tween^®80, propylene glycol at a ratio of 5:4:1 loaded with levofloxacin. The formulated levofloxacin-loaded limonene-based nanoemulsion physiochemical properties namely; droplet size, polydispersity index, zeta potential, and in-vitro drug release were studied and stability over three months was assessed. Furthermore, in-vitro antimicrobial susceptibility was investigated on biofilm-forming MRSA strain through kinetics of killing and biofilm assay. The in-situ nanoemulgel ocular irritation was studied by HET-CAM test. The results demonstrated that levofloxacin-loaded limonene-based nanoemulsion had a particle size of 119 ± 0.321 nm with improved eradicating efficacy of MRSA biofilm, where the MIC of the loaded nanoemulgel was 3.12 mg/ml significantly less than that of drug alone (6.25 mg/ml). HET-CAM test showed no signs of hemorrhage, coagulation, or lysis for the loaded nanoemulgel same as sodium chloride solution (negative control) where its irritation score was zero compared to 9.87 for the positive irritant group (1%w/v sodium lauryl sulfate). In conclusion, the current investigation provided a strong foundation for further studies of limonene nanoemulgel as a potential complementary therapeutic agent against resistant bacterial strains.

Evaluation of microneedles-assisted in situ depot forming poloxamer gels for sustained transdermal drug delivery

In this study, for the first time, we have reported a sustained transdermal drug delivery from thermoresponsive poloxamer depots formed within the skin micropores following microneedle (MN) application. Firstly, we have investigated the sol–gel phase transition characteristics of poloxamers (PF®127, P108, and P87) at physiological conditions. Rheological measurements were evaluated to confirm the critical gelation temperature (CGT) of the poloxamer formulations with or without fluorescein sodium (FS), as a model drug, at various concentrations. Optimized poloxamer formulations were subjected to in vitro release studies using a vial method. Secondly, polymeric MNs were fabricated using laser-engineered silicone micromolds from various biocompatible polymeric blends of Gantrez S-97, PEG 10000, PEG200, PVP K32, and PVP K90. The MN arrays were characterized for mechanical strength, insertion force determination, in situ dissolution kinetics, moisture content, and penetration depth. The optimized MN arrays with good mechanical strength and non-soluble nature were used to create micropores in the neonatal porcine skin. Microporation in neonatal porcine skin was confirmed by dye-binding study, skin integrity assessment, and histology study. Finally, the in vitro delivery of FS from optimized poloxamer formulations was conducted across non-porated vs microporated skin samples using vertical Franz diffusion cells. Results concluded that permeation of FS was sustained for 96 h across the MN-treated skin samples containing in situ forming depot poloxamer formulations compared to non-microporated skin which sustained the FS delivery for 72 h. Confocal microscopic images confirmed the distribution of higher florescence intensity of FS in skin tissues after permeation study in case of MN-treated skin samples vs intact skin samples.

Intravesical delivery of rapamycin via folate-modified liposomes dispersed in thermo-reversible hydrogel

Purpose

To develop an intravesical instillation system for the treatment of bladder cancer, rapamycin (Rap) was encapsulated into liposomes and then homogeneously dispersed throughout a poloxamer 407 (P407)-based hydrogel.

Methods

Rap-loaded conventional liposomes (R-CL) and folate-modified liposomes (R-FL) were prepared using a film hydration method and pre-loading technique, and characterized by particle size, drug entrapment efficiency, and drug loading. The cellular uptake behavior in folate receptor-expressing bladder cancer cells was observed by flow cytometry and confocal laser scanning microscopy using a fluorescent probe. In vitro cytotoxic effects were evaluated using MTT assay, colony forming assay, and Western blot. For in vivo intravesical instillation, Rap-loaded liposomes were dispersed in P407-gel, generating R-CL/P407 and R-FL/P407. Gel-forming capacities and drug release were evaluated. Using the MBT2/Luc orthotopic bladder cancer mouse model, in vivo antitumor efficacy was evaluated according to regions of interest (ROI) measurement.

Results

R-CL and R-FL were successfully prepared, at approximately <160 nm, 42% entrapment efficiency, and 57 μg/mg drug loading. FL cellular uptake was enhanced over 2-fold than that of CL; folate receptor-mediated endocytosis was confirmed using a competitive assay with folic acid pretreatment. In vitro cytotoxic effects increased dose-dependently. Rap-loaded liposomes inhibited mTOR signaling and induced autophagy in urothelial carcinoma cells. With gelation time of <30 seconds and gel duration of >12 hrs, both R-CL/P407 and R-FL/P407 preparations transformed into gel immediately after instillation into the mouse bladder. Drug release from the liposomal gel was erosion controlled. In orthotopic bladder cancer mouse model, statistically significant differences in ROI values were found between R-CL/P407 and R-FL/P407 groups at day 11 (P=0.0273) and day 14 (P=0.0088), indicating the highest tumor growth inhibition by R-FL/P407.

Conclusion

Intravesical instillation of R-FL/P407 might represent a good candidate for bladder cancer treatment, owing to its enhanced retention and FR-targeting.

Development of Topical Delivery Systems for Flightless Neutralizing Antibody

Flightless I (Flii) is an actin remodeling protein important for cytoskeletal regulation and cellular processes including migration, proliferation, and adhesion. Previous studies have clearly identified Flii as a novel therapeutical target for improved wound repair and have demonstrated Flii regulation using Flii neutralizing antibodies (FnAb) in different models of wound healing in vivo. Here we describe the development of an optimized topical delivery system that can neutralize Flii activity in the epidermis. Topical delivery of FnAb is an attractive approach as it provides a convenient application, sustained release, localized effect, and reduced dosage. Three successful formulations were developed, and their physical and chemical stability examined. The in vitro release revealed prolonged and sustained release of FnAb in all the tested formulations. Additionally, penetration studies using intact porcine skin showed that FnAb penetrated the epidermis and upper papillary dermis. The penetrated FnAb significantly reduced Flii expression compared to dosed matched IgG controls. This study has successfully developed a topical delivery system for FnAb that could serve as a potential platform for future localized wound treatments.

Novel self-assembled tacrolimus nanoparticles cross-linking thermosensitive hydrogels for local rheumatoid arthritis therapy

The aim was to explore the potential application of novel self-assembled nanoparticles cross-linking thermosensitive hydrogels composed of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (Soluplus) and tacrolimus (FK-506) for local therapy of rheumatoid arthritis (RA). The sol-gel transition temperature (T_sol-gel), gelation time, rheological behaviors, in vitro release, in vivo gelation and retention, and therapeutic efficacy against adjuvant-induced arthritis (AIA) rats were compared between the Soluplus hydrogels and widely studied poloxamer 407 (P407) delivery systems. In sol, the spherical and uniform FK506 loaded Soluplus nanoparticles (Soluplus-SNPs) were self-assembled with encapsulation efficiency of 99.5±1.5% and particle size of 73.9±2.9nm. The decreased T_sol-gel of Soluplus-SNPs hydrogels was associated with the addition of salts, elevation of pH and ionic strength. The optimal T_sol-gel of Soluplus-SNPs with concentrations of 10%-30% in phosphate buffer (50mM, pH 7.4) was from 37.4±0.1°C to 32.8±0.3°C and the gelation time was not greater than 2min. Soluplus-SNPs gelling systems showed lower viscosity and wider range concentrations in sol state at 25°C and stronger gel strength at 37°C than P407, which resulting in longer sustained release of FK506 but without burst-release in vitro, and longer retention time in the local injection site in vivo. The therapeutic efficacy to treat AIA rats was significantly enhanced from d10 to d17 after a single dose of FK506 loaded in 10% and 20% Soluplus-SNPs hydrogels. In conclusion, Soluplus-SNPs hydrogel is a potential sustainable delivery system for FK506 to treat RA locally.

Safety and efficacy of Intraurethral Mitomycin C Hydrogel for prevention of post-traumatic anterior urethral stricture recurrence after internal urethrotomy

BACKGROUND

Evaluation of the safety and efficacy of intraurethral Mitomycin C (MMC) hydrogel for prevention of post-traumatic anterior urethral stricture recurrence after internal urethrotomy.

METHODS

A thermoresponsive hydrogel base consisting of 0.8 mg MMC with 1cc water and propylene glycol to PF-127 poloxamer was used in theater. 40 male patients with short, non-obliterated, urethral stricture were randomized into 2 groups: control and MMC. After internal urethrotomy, the MMC group patients received the MMC-Hydrogel while the others were just catheterized. Both groups had their catheters for at least 1 week. After surgery, they were followed up by means of medical history and physical examination, monitoring voiding patterns and retrograde urethrogram at 1 month, 6 months and 1 year after surgery.

RESULTS

40 male patients between 14 to 89 years old (Mean = 54.15) underwent internal urethrotomy. The average age for the control and MMC group was 54.55±21.25 and 53.75±24.75 respectively. In a comparison of age between the two groups, they were matched (P=0.574). Stricture length was 10.7±5.9 and 9.55±4.15 mm for the control and MMC group respectively. There were no statistically meaningful differences between the two groups (P=0.485). Fifteen patients had a history of one previous internal urethrotomy which in a comparison between the two groups meant there was no meaningful difference (P=0.327). During postoperative follow up, total urethral stricture recurrence happened in 12 patients: 10 patients (50%) in control group and 2 patients (10%) in MMC group. The difference was statistically significant (P=0.001). There were no significant complications associated with the MMC injection in our patients.

CONCLUSIONS

Based on our results, MMC Hydrogel may have an anti-fibrotic action preventing post-traumatic anterior urethral stricture recurrence with no side effects on pre-urethral tissue. Due to our study limitations, our follow up time and the small number of patients, our results were not conclusive and further studies will be needed with a longer follow up time.

Hybrid cross-linked hydrogels based on fibrous protein/block copolymers and layered silicate nanoparticles: tunable thermosensitivity, biodegradability and mechanical durability

Schematic representation of LAPONITE® reinforced pluronic/chitosan/keratin nanocomposite hydrogel crosslinked with Genipin.

Evaluation of an injectable thermosensitive hydrogel as drug delivery implant for ocular glaucoma surgery

In this study, a biodegradable thermo-sensitive hydrogel from poly(trimethylene carbonate)₁₅-F127-poly(trimethylene carbonate)₁₅ (PTMC₁₅-F127-PTMC₁₅) was designed and evaluated as an injectable implant during ocular glaucoma filtration surgery in vivo and in vitro. Mitomycin C (MMC) was loaded into this hydrogel for controlled released to prolong the efficacy and to reduce the long-term toxicity. The properties of the hydrogel were confirmed using ¹H NMR and gel permeation chromatography (GPC). Compared to the Pluronic F127 hydrogel, the PTMC₁₅-F127-PTMC₁₅ hydrogel showed a good solution-gel transition temperature at 37°C, a lower work concentration of 5% w/v and a longer mass loss time of more than 2 weeks. The in vitro study showed that the drug could be released from PTMC₁₅-F127-PTMC₁₅ (5% w/v) hydrogel for up to 16 days with only 57% of drug released in the first day. Moreover, the cell toxicity, which was tested via LDH and ANNEXIN V/PI, decreased within 72 h in human tenon's fibroblast cells (HTFs). The in vivo behavior in a rabbit glaucoma filtration surgery model indicated that this hydrogel loaded with 0.1 mg/ml MMC led to a better functional bleb with a prolonged mean bleb survival time (25.5±2.9 days). The scar tissue formation, new collagen deposition and myofibroblast generation appeared to be reduced upon histological and immunohistochemistry examinations, with no obvious side effects and inflammatory reactions. The in vitro and in vivo results demonstrated that this novel hydrogel is a safe and effective drug delivery candidate in ocular glaucoma surgery.

Properties of bioadhesive ketoprofen liquid suppositories: preparation, determination of gelation temperature, viscosity studies and evaluation of mechanical properties using texture analyzer by 4 × 4 factorial design

CONTEXT

Development and evaluation of thermosensitive and bioadhesive liquid suppositories containing ketoprofen (KP).

OBJECTIVE

This study was conducted to develope thermosensitive and bioadhesive liquid suppositories containing KP using poloxamer and different bioadhesive polymers and to investigate their gelation temperature, viscosity and mechanical properties.

MATERIALS AND METHODS

Bioadhesive liquid suppositories were prepared by the cold method using poloxamer 407 (P 407), Poloxamer 188 (P 188) and various amounts of different bioadhesive polymers. Their gelation temperatures, viscosity values and mechanical properties were determined using texture analyzer by 4 × 4 factorial design.

RESULTS

It was seen that in presence of KP, gelation temperature of formulation P 407/P 188 (4/20%) significantly decreased from 64 to 37.1 °C. It is to be noted that addition of increasing concentrations of bioadhesive polymers lowered gelation temperature and its decrease was highest with addition of Carbopol 934 P (C). Results of texture profile analysis (TPA) showed that formulations containing C have significantly higher hardness and adhesiveness values than other bioadhesive formulations. According to TPA, gel structure of liquid suppository formulation F5, containing P 407/P 188/KP/C (4/20/2.5/0.8%), exhibited the greatest hardness, compressibilty, adhesiveness and besides greatest viscosity.

DISCUSSION AND CONCLUSION

According to mechanical properties and viscosity values, it was concluded that F5 could be a promising formulation.

A thermosensitive morphine-containing hydrogel for the treatment of large-scale skin wounds

PURPOSE

Topically applied opioids are an option to induce efficient analgesia in patients with severe skin wounds. For ongoing pain reduction, the vehicle should provide sustained drug release in order to increase the intervals during the regular wound dressing changes. In addition, the formulation should not impair wound healing. Hydrogels provide a moist wound environment, which is known to facilitate the healing process.

METHODS AND RESULTS

Investigating poloxamer hydrogels as a carrier system for morphine in terms of release behavior and (per-)cutaneous absorption, poloxamer 407 25wt.% hydrogel sustained morphine release up to 24h. The drug release rate decreased with increasing concentration of the gel forming triblock copolymer. Poloxamer 407 25wt.% hydrogel retarded morphine uptake into reconstructed human skin and percutaneous drug absorption compared to a hydroxyethyl cellulose reference gel.

CONCLUSIONS

The results of our in vitro study indicate that the thermosensitive poloxamer 407 25wt.% hydrogel is an appropriate carrier system for the topical application of morphine with regard to sustained drug release and ongoing analgesia.

Bone induction through controlled release of novel BMP-2-related peptide from PTMC₁₁-F127-PTMC₁₁ hydrogels

Bone morphogenetic protein 2 (BMP-2) is the most powerful osteogenic factor; its effectiveness in enhancing osteoblastic activation has been confirmed both in vitro and in vivo. We developed a novel peptide (designated P24) derived from the 'knuckle' epitope of BMP-2 and found it also had osteogenic bioactivity to some extent. The main objective of this study was to develop a controlled release system based on poly(trimethylene carbonate)-F127-poly(trimethylene carbonate) (PTMC₁₁-F127-PTMC₁₁) hydrogels for the P24 peptide, to promote bone formation. By varying the copolymer concentrations, we demonstrated that P24/PTMC₁₁-F127-PTMC₁₁ hydrogels were an efficient system for the sustained release of P24 over 21-35 days. The P24-loaded hydrogels elevated alkaline phosphatase activity and promoted the expression of osteocalcin mRNA in bone marrow stromal cells (BMSCs) in vitro. Radiographic and histological examination showed that P24-loaded hydrogels could induce more effective ectopic bone formation in vivo than P24-free hydrogels. These results indicate that the PTMC₁₁-F127-PTMC₁₁ hydrogel is a suitable carrier for the controlled release of P24, and is a promising injectable biomaterial for the induction of bone regeneration.

Biomedical Applications of Biodegradable Polymers

Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. In order to fit functional demand, materials with desired physical, chemical, biological, biomechanical and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.