Analgesia Effect of Enteric Sustained-Release Tetrodotoxin Pellets in the Rat

Tetrodotoxin (TTX) was identified as a latent neurotoxin that has a significant analgesia effect. It was rapidly absorbed and excreted in rat after intramuscular (i.m.) injection. To maintain the effect, frequent injections were required. The enteric sustained-release TTX pellets with sucrose pellets as a drug carrier was prepared by fluidized bed spray irrigation, coated in sequence with Eudragit NE30D as a sustained-release layer, hydroxypropyl methylcellulose (HPMC) as a barrier layer and Eudragit L30D-55 as an enteric coating. TTX in the pellets could be sustained released for 12 h in dissolution test. In vivo, TTX pellets reached C_max at 5 h, and t_1/2 was 14.52 ± 2.37 h after intragastrically (i.g.) administration in rat. In acetic acid induced writhing test in rat, the pellets at the dosages of 20, 40, 60 and 80 μg·kg⁻¹ produced analgesic effect at about 1.5 h to 9 h and the strongest effect was at about 3 h to 6 h. Simultaneously, the LD₅₀ of the enteric sustained-release TTX pellets was 840.13 μg·kg⁻¹, and the ED50 was about 30 μg·kg⁻¹. Thus, the therapeutic index was about 25. The enteric sustained-release TTX pellets with absolute analgesia effect and greatly enhanced safety was prepared.

Pharmacokinetics and relative bioavailability of meloxicam oil suspension in pigs after intramuscular administration

This study aimed to develop one novel meloxicam (MEL) oil suspension for sustained-release and compare the pharmacokinetic characteristics of it with MEL conventional formulation in pigs after a single intramuscular administration. Six healthy pigs were used for the study by a crossover design in two periods with a withdrawal interval of 14 days. Plasma concentrations of MEL were measured by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Pharmacokinetic parameters were calculated by noncompartmental methods. The difference was statistically significant (p < .05) between MEL oil suspension and MEL conventional formulation in pharmacokinetic parameters of mean residence time (6.16 ± 4.04) hr versus (2.66 ± 0.55) hr, peak plasma concentration (C_max ) (0.82 ± 0.12) µg/ml versus (1.12 ± 0.22) µg/ml, time needed to reach C_max (T_max ) (2.33 ± 0.82) hr versus (0.59 ± 0.18) hr, and terminal elimination half-life (t_1/2λz ) (3.74 ± 2.66) hr versus (1.55 ± 0.37) hr. The mean area under the concentration-time curve (AUC_0-∝ ) of MEL oil suspension and MEL conventional formulation was 5.35 and 3.43 hr µg/ml, respectively, with a relative bioavailability of 155.98%. Results of the present study demonstrated that the MEL oil suspension could prolong the effective time of drugs in blood, thereby reducing the frequency of administration on a course of treatment. Therefore, the novel MEL oil suspension seems to be of great value in veterinary clinical application.

Application of Solid Dispersion Technique to Improve Solubility and Sustain Release of Emamectin Benzoate

The solid dispersion technique, which is widely used in the medical field, was applied to prepare a pesticide dosage form of emamectin benzoate (EM). The preparation, physicochemical characterization, aqueous solubility, release dynamics, photolytic degradation, bioactivity, and sustained-release effects of the prepared EM solid dispersions were studied by a solvent method, using polymer materials as the carriers. Water-soluble polyvinyl pyrrolidone (PVP) K30 and water-insoluble polyacrylic resin (PR)III were used as the carriers. The influence of various parameters, such as different EM:PVP-K30 and EM:PRIII feed ratios, solvent and container choices, rotational speed and mixing time effects on pesticide loading, and the entrapment rate of the solid dispersions were investigated. The optimal conditions for the preparation of EM-PVP-K30 solid dispersions required the use of methanol and a feed ratio between 1:1 and 1:50, along with a rotational speed and mixing time of 600 rpm and 60 min, respectively. For the preparation of EM-PRIII solid dispersions, the use of methanol and a feed ratio between 1:4 and 1:50 were required, in addition to the use of a porcelain mortar for carrying out the process. Under optimized conditions, the prepared EM-PVP-K30 solid dispersions resembled potato-like, round, and irregular structures with a jagged surface. In contrast, the EM-PRIII solid dispersions were irregular solids with a microporous surface structure. The results of X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), ultraviolet (UV) spectrometry, and infrared (IR) spectrometry showed that the solid dispersions were formed by intermolecular hydrogen bonding. The solid dispersion preparation in PVP-K30 significantly improved the solubility and dissolution rate of EM, particularly the aqueous solubility, which reached a maximum of 37.5-times the EM technical solubility, when the feed ratio of 1:10 was employed to prepare the dispersion. Importantly, the wettable powder of EM-PVP-K30 solid dispersion enhanced the insecticidal activity of EM against the Plutella xylostella larvae. Furthermore, the solid dispersion preparation in PRIII afforded a significant advantage by prolonging the EM technical release in water at a pH below 7.0, especially when the PRIII content in solid dispersions was high. While the amplified toxicity of the wettable powder of EM-PRIII solid dispersions against the P. xylostella larvae showed no significant differences from that of the EM technical, the long-term toxicity under the field condition was much better than that of the commercially available EM 1.5% emulsifiable concentrate. Notably, solid dispersions with both the PVP-K30 and PRIII carriers reduced the effect of UV photolysis.

Fabrication and Characterization of Silk Fibroin/Curcumin Sustained-Release Film

In the present work, a sustained-release film composed of silk fibroin (SF), curcumin (Cur), glutaraldehyde (GA), and glycerol (Gly) was prepared successfully for wound dressings. Features relevant to wound dressings of SF/Gly/GA/Cur film were assessed. Physical and chemical properties of the fabricated materials were also characterized. The results showed that the prepared SF/Gly/GA/Cur film demonstrated a good sustained-release performance, flexibility, and gas permeability. In addition, it was found that the prepared SF/Gly/GA/Cur film possessed the capability to effectively inhibit the growth of bacteria and prevent bacterial penetration with a suitable water vapor transmission rate. Furthermore, the prepared composite film was non-cytotoxic, which makes it an ideal material for wound dressings.

Gemcitabine-loaded RGD modified liposome for ovarian cancer: preparation, characterization and pharmacodynamic studies

Background

Ovarian cancer is the third leading cause of death among gynecological cancers in women in China. Chemotherapy is an important method for comprehensive treatment of ovarian cancer, but the curative effect is poor.

Purpose

In this study, gemcitabine (GEM) -loaded RGD modified liposomes (LPs) were developed by the emulsification-solvent evaporation method and evaluated for their antitumor activity in vitro and in vivo.

Methods

The physicochemical properties of LPs such as particle size, zeta potential and in vitro drug release were investigated. We also demonstrated the effect of RGD-GEM-PEG LPs in ovarian cancer.

Results

RGD-PEG3500-DSPE GEM LPs had a uniform spherical morphology. The mean particle size and polydispersity index were determined to be 106.7 nm and 0.13 respectively. The ER% and DL% of the formulation were 79.6±3.1% and 6.1±1.4% respectively. Compared with the free drug, RGD modified GEM LPs had sustained-release properties in vitro. In vivo, compared with the DiD-RGD-PEG3500-DSPE GEM LPs group, free DiD-GEM and DiD-GEM LPs had no obvious fluorescence intensity in tumor of mice at all times, indicating that ordinary liposomes and drugs had no tumor targeting function. RGD-PEG3500-DSPE GEM LPs showed a superior antiproliferative effect on SKOV3 cells and had a better antitumor effect in vivo than non-modified LPs.

Conclusion

These results indicated that RGD-PEG3500-DSPE GEM LPs were a promising candidate for antitumor drug delivery.

Biomimetic Pulsating Vesicles with Both pH-Tunable Membrane Permeability and Light-Triggered Disassembly-Re-assembly Behaviors Prepared by Supra-Amphiphilic Helices

The reversible unfolding-refolding transition is considerably important for natural elastomeric proteins (e.g., titin) to fulfill their biological functions. It is of great importance to develop synthetic versions by borrowing their unique stretchable design principles. Herein, we present a novel pulsating vesicle by means of the aqueous self-assembly of supra-amphiphilic helices. Interestingly, this vesicle simultaneously features dynamic swelling and shrinkage movements in response to external proton triggers. Titin-like unfolding-refolding transformation of artificial helices was proved to play a crucial role in this pulsatile motion. Moreover, the vesicular membrane of this vesicle has exhibited tunable permeability during reversible expansion and contraction circulation. Meanwhile, light can also be used as a driving force to further regulate the disassembly-reassembly transformation of the pulsating vesicle. In addition, the drug delivery system was also employed as an investigating model to estimate the permeability variation and disassembly-reassembly behaviors of the pulsating vesicles, which displayed unique dual quick- and sustained-release behaviors toward anti-cancer agents. It is anticipated that this work opens an avenue for fabricating novel stretchable biomimetics by using the exclusive unfolding-refolding nature of artificial foldamers.

Silk Fibroin as a Novel Alcohol-Resistant Excipient for Sustained-Release Tablet Formulation

Concomitant intake of alcoholic beverages with sustained-release oral formulations may potentially lead to dose dumping. Alcohol-resistance testing is currently a requirement for the manufacturers by regulatory authorities. Silk fibroin produced by silkworm Bombyx mori is suggested in this work as a potential alternative to a narrow spectrum of alcohol-resistant excipients. Oxycodone HCl, tramadol HCl, and flurbiprofen were selected as model drugs and formulated with regenerated silk fibroin either in the form of an amorphous solid dispersion or as a physical mixture and compressed into tablets. Preliminary compactability and tampering-resistance studies were performed. The ethanol-resistance was tested in media containing 5%, 10%, 20%, or 40% (v/v) ethanol concentration. Drug release profiles were compared using f₂ similarity factor. Good mechanical tampering-resistance (tensile strength of 14.6 MPa at 400 MPa compression pressure) was obtained for tablets compressed from physical mixture. Tablets compressed from amorphous solid dispersion had lower tensile strength (2.2 MPa) but showed chemical tampering-resistance to extraction by pure ethanol (7.1% of oxycodone HCl after 24 h). Drug release is controlled predominantly by swelling and diffusion. With an increasing ethanol concentration in release medium, the tablets swelled less, resulting in a slower release. This trend was similar for all tested drugs and for both physical states formulations. No dose dumping occurred in the presence of ethanol; therefore, silk fibroin could be considered as an alternative alcohol-resistant excipient for sustained release application.

Pharmacokinetics of a Sustained-release Formulation of Meloxicam After Subcutaneous Administration to Hispaniolan Amazon Parrots (Amazona ventralis)

Meloxicam has been shown to have a safe and favorable pharmacodynamic profile with individual variability in Hispaniolan Amazon parrots (Amazona ventralis). In the current study, we determined the pharmacokinetics of a sustained-release formulation of meloxicam after subcutaneous administration to Hispaniolan Amazon parrots. Twelve healthy adult parrots, 6 males and 6 females, were used in the study. Blood samples were collected before (time 0) and at 0.5, 1, 2, 6, 12, 24, 48, 72, 96, and 120 hours after a single dose of the sustained-release meloxicam formulation (3 mg/kg SC). Plasma meloxicam concentrations were measured by high-pressure liquid chromatography. Pharmacokinetic parameters were determined by noncompartmental analysis. Plasma concentrations reached a mean C_max of 23.4 μg/mL (range, 14.7-46.0 μg/mL) at 1.8 hours (range, 0.5-6 hours), with a terminal half-life of 7.4 hours (range, 1.4-40.9 hours). Individual variation was noticeable, such that some parrots (4 of 12 birds) had very low plasma meloxicam concentrations, similar to the high variability reported in a previous pharmacokinetic study of the standard meloxicam formulation in the same group of birds. Two birds developed small self-resolving scabs at the injection site. On the basis of these results, the sustained-release meloxicam formulation could be administered every 12 to 96 hours in Hispaniolan Amazon parrots to manage pain. Because of these highly variable results, the use of this formulation in this species cannot be recommended until further pharmacokinetic, safety, and pharmacogenomic evaluations are performed to establish accurate dosing recommendations and to understand the high pharmacokinetic variability.

Preparation, In Vivo and In Vitro Release of Polyethylene Glycol Monomethyl Ether-Polymandelic Acid Microspheres Loaded Panax Notoginseng Saponins

In order to enrich the types of Panax notoginseng saponins (PNS) sustained-release preparations and provide a new research idea for the research and development of traditional Chinese medicine sustained-release formulations, a series of Panax notoginseng saponins microspheres was prepared by a double emulsion method using a series of degradable amphiphilic macromolecule materials polyethylene glycol monomethyl ether-polymandelic acid (mPEG-PMA) as carrier. The structure and molecular weight of the series of mPEG-PMA were determined by nuclear magnetic resonance spectroscopy (1 HNMR) and gel chromatography (GPC). The results of the appearance, particle size, drug loading and encapsulation efficiency of the drug-loaded microspheres show that the mPEG10000-PMA (1:9) material is more suitable as a carrier for loading the total saponins of Panax notoginseng. The particle size was 2.51 ± 0.21 μm, the drug loading and encapsulation efficiency were 8.54 ± 0.16% and 47.25 ± 1.64%, respectively. The drug-loaded microspheres were used for in vitro release and degradation experiments to investigate the degradation and sustained release behaviour of the drug-loaded microspheres. The biocompatibility of the microspheres was studied by haemolytic, anticoagulant and cytotoxicity experiments. The pharmacological activity of the microspheres was studied by anti-inflammatory and anti-tumour experiments. The results showed that the drug-loaded microspheres could be released stably for about 12 days and degraded within 60 days. At the same time, the microspheres had good biocompatibility, anti-inflammatory and anti-tumour activities.

Preparing of aspirin sustained-release granules by hot-melt granulation and micro-crystal coating

In this work, aspirin (ASP) sustained granules were prepared using micro-crystal coating and hot-melt granulation, respectively. In the process of micro-crystal coating, PVP was used to form the isolation layer and then coated with either Eudragit RS/RL30D or ethyl cellulose (EC) as sustained-release layers to prepare sustained granules (the granules from this method were denoted m-cG). And in the process of hot-melt granulation, the granules were obtained with stearyl alcohol as a binder and EC as matrix material to prepare sustained granules (the granules were denoted h-mG). The in vitro release of ASP sustained-release granules was investigated by dissolution apparatus and the stability of the granules was studied. Since both methods effectively prevented the hydrolysis of ASP, the sustained granules by micro-crystal coating and hot-melt granulation were stable. However, there was a clear difference in the in vitro release of h-mG and m-cG. The h-mG was completely released in 4 h, while the m-cG with EC as sustained-release layer released 80% in 24 h and the m-cG with the Eudragit RS/RL 30 D as sustained-release layer released completely in 5 h. The results showed that micro-crystal coating was more suitable for the preparation of ASP sustained granules, and the granules with EC as sustained layer could achieve a better sustained-release effect.

Addition of free poloxamer 407 to a new gene vector P407-PEI-K12 solution forms a sustained-release in situ hypergel that enhances cell transfection and extends gene expression

To address the concern around the efficiency/cytotoxicity ratio and the tumor-targeting effects of polyethylenimine (PEI), is a non-viral gene vector used for the delivery of the cancer therapy gene, poloxamer 407 (P407)-PEI-K12, was synthesized by cross-linking low-molecular weight PEI with P407 and further coupling a bifunctional peptide, K12, which is comprised of the tumor-targeting peptide tLyP-1 and the nuclear localization sequence. Furthermore, the addition of free P407 into the polymer/DNA complex solution produced a temperature-sensitive in situ gel-P407/P407-PEI-K12/DNA complex, which improved the effects of sustained-release gene delivery and transfection efficiency. The specificity, cytotoxicity and gene transfection efficiency of P407-PEI-K12 was investigated in Hela cells in vitro. The polymer efficiently prevented the degradation of plasmid DNA by DNase I and had a marked ability for serum tolerance. Agarose gel electrophoresis revealed that plasmid DNA was efficiently condensed and protected. The higher transfection efficiency of P407-PEI-K12h (the molar ratio of P407-PEI and K12 is 1:10) was achieved with a polymer and plasmid DNA ratio (w/w) of 20:1. The ability of free P407 to promote the transfection of the polymer/DNA complex was high (0.09%). The half-life of the P407/P407-PEI-K12-h/DNA gel complex was 228 min, and the transfection efficiency of the P407/P407-PEI-K12-h/DNA complex was markedly higher compared to that of the P407-PEI-K12-h/DNA complex at various release times.

Insulin-like growth factor 1 sustained-release collagen on urethral catheter prevents stricture after urethral injury in a rabbit model

OBJECTIVES

To evaluate the preventive effect of an insulin-like growth factor 1 sustained-release collagen urethral catheter on urethral stricture after urethral injury in a rabbit model.

METHODS

We made urethral catheters coated either with insulin-like growth factor 1 impregnated collagen or with only collagen, and we divided 19 male Japanese white rabbits into three groups according to the kind of catheter inserted immediately after the rabbit's urethra was injured by electrocoagulation. Group 1 (n = 7) had a catheter coated with insulin-like growth factor 1 impregnated collagen inserted; group 2 (n = 7) had a catheter coated with only collagen inserted; and group 3 (n = 5) had an uncoated catheter inserted. A total of 14 days later, the injured urethras were evaluated by urethrography and urethroscopy, and were also histologically examined.

RESULTS

Urethrography showed that the ratio of the urethral lumen diameter in injured urethra to that in normal urethra was the largest in group 1 (P < 0.0001). In addition, five of the seven rabbits in group 1 (71.4%) had a urethral lumen large enough for passage of a urethroscope, a fraction larger than the corresponding fractions in groups 2 (57.1%) and 3 (20%). On histological analysis, the injured area not covered with regenerated urethral epithelium tended to be smaller in group 1 than the other two groups, but the mean difference was not significant (P = 0.19).

CONCLUSIONS

An insulin-like growth factor 1 sustained-release collagen urethral catheter significantly improves wound healing and prevents urethral stricture after urethral injury.

Biocompatible Fe-Based Micropore Metal-Organic Frameworks as Sustained-Release Anticancer Drug Carriers

Sustained-release preparation is a hot spot in antitumor drug research, where the first task is to select suitable drug carriers. Research has revealed that carboxylic acid iron metal⁻organic frameworks (MOFs), constructed from iron (Fe) ions and terephthalic acid, are nontoxic and biocompatible. Due to the breathing effect, the skeleton of this mesoporous material is flexible and can reversibly adapt its pore size through drug adsorption. Therefore, we chose one kind of Fe-MOF, MIL-53(Fe), as a carrier for the anticancer drug oridonin (Ori). In this work, we report the design and synthesis of MIL-53(Fe) and explore its ability as a transport vehicle to deliver Ori. MIL-53(Fe) is characterized by scanning electron microscopy and X-ray powder diffraction. A loading capacity of 56.25 wt % was measured by high performance liquid chromatography. This carrier was safe and nontoxic (cell viability > 95.27%), depending on the results of 3-(4,5-dimethylthiazol-2-yl)--2,5-diphenyltetrazolium bromide assays, lactate dehydrogenase assays, and Annexin V-fluoresce isothiocyanate/propidium iodide double-staining assays. After loading the drug, the structure of the MIL-53(Fe) was not destroyed, and Ori was amorphous in MIL-53(Fe). Based on an analysis of the Ori release profile, results suggest that it lasts for more than seven days in vitro. The cumulative release rate of Ori at the seventh day was about 82.23% and 91.75% in phosphate buffer saline solution at 37 °C under pH 7.2 and pH 5.5, respectively. HepG2 cells were chosen to study the cytotoxicity of Ori@MIL-53(Fe), and the results show that the anticancer ratio of Ori@MIL-53(Fe) system reaches 90.62%. Thus, MIL-53 can be used as a carrier for anticancer drugs and Ori@MIL-53(Fe) is a promising sustained-release drug delivery system for the cancer therapy.

Preparation of a Sustained-Release Nebulized Aerosol of R-terbutaline Hydrochloride Liposome and Evaluation of Its Anti-asthmatic Effects via Pulmonary Delivery in Guinea Pigs

An aerosolized liposome formulation for the pulmonary delivery of an anti-asthmatic medication was developed. Asthma treatment usually requires frequent administration of medication for a sustained bronchodilator response. Liposomes are known for their sustained drug release capability and thus would be a suitable delivery system for prolonging the therapeutic effect of anti-asthmatic medication. Liposomes prepared by thin film hydration were loaded with a model drug, R-terbutaline hydrochloride(R-TBH), using an ammonium sulfate-induced transmembrane electrochemical gradient. This technique provided an encapsulation efficiency of up to 71.35% and yielded R-TBH liposomes with a particle size of approximately 145 ± 20 nm. According to stability studies, these R-TBH liposomes should be stored at 4°C before usage. Compared to R-TBH solution, which showed 90.84% release within 8 h, liposomal R-TBH had a cumulative release of 73.53% at 37°C over 192 h. A next generation impactor (NGI) was used to analyze the particle size distribution in the lungs of R-TBH liposome aerosol in vitro at 5°C. The therapeutic efficacy of the nebulized aerosol of the R-TBH liposomes was assessed via pulmonary delivery in guinea pigs. The results showed that, compared to the R-TBH solution group, the R-TBH liposome group had a prolonged anti-asthma effect.

Temperature-sensitive heparin-modified poloxamer hydrogel with affinity to KGF facilitate the morphologic and functional recovery of the injured rat uterus

Endometrial injury usually results in intrauterine adhesion (IUA), which is an important cause of infertility and recurrent miscarriage in reproductive women. There is still lack of an effective therapeutic strategy to prevent occurrence of IUA. Keratinocyte growth factor (KGF) is a potent repair factor for epithelial tissues. Here, a temperature-sensitive heparin-modified poloxamer (HP) hydrogel with affinity to KGF (KGF-HP) was used as a support matrix to prevent IUA and deliver KGF. The rheology of KGF-HP hydrogel was carefully characterized. The cold KGF-HP solution was rapidly transited to hydrogel with suitable storage modulus (G') and loss modulus (G″) for the applications of uterus cavity at temperature of 33 °C. In vitro release demonstrated that KGF was released from HP hydrogels in sustained release manner for a long time. In vivo bioluminescence imaging showed that KGF-HP hydrogel was able to prolong the retention of the encapsulated KGF in injured uterus of rat model. Moreover, the morphology and function of the injured uterus were significantly recovered after administration of KGF-HP hydrogel, which were evaluated by two-dimensional ultrasound imaging and receptive fertility. Not only proliferation of endometrial glandular epithelial cells and luminal epithelial cells but also angiogenesis of injured uterus were observed by Ki67 and CD31 staining after 7 d of treatment with KGF-HP hydrogel. Finally, a close relatively relationship between autophagy and proliferation of endometrial epithelial cells (EEC) and angiogenesis was firstly confirmed by detecting expression of LC3-II and P62 after KGF treatment. Overall, KGF-HP may be used as a promising candidate for IUA treatment.

Sustained-release solid dispersion of pelubiprofen using the blended mixture of aminoclay and pH independent polymers: preparation and in vitro/in vivo characterization

The present study aimed to develop the sustained-release oral dosage form of pelubiprofen (PEL) by using the blended mixture of 3-aminopropyl functionalized-magnesium phyllosilicate (aminoclay) and pH-independent polymers. The sustained-release solid dispersion (SRSD) was prepared by the solvent evaporation method and the optimal composition of SRSD was determined as the weight ratio of drug: Eudragit® RL PO: Eudragit® RS PO of 1:1:2 in the presence of 1% of aminoclay (SRSD(F6)). The dissolution profiles of SRSD(F6) were examined at different pHs and in the simulated intestinal fluids. The drug release from SRSD(F6) was limited at pH 1.2 and gradually increased at pH 6.8, resulting in the best fit to Higuchi equation. The sustained drug release from SRSD(F6) was also maintained in simulated intestinal fluid at fasted-state (FaSSIF) and fed-state (FeSSIF). The structural characteristics of SRSD(F6) were examined by using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR), indicating the change of drug crystallinity to an amorphous form. After oral administration in rats, SRSD(F6) exhibited the prolonged drug exposure in plasma. For both PEL and PEL-transOH (active metabolite), once a day dosing of SRSD(F6) achieved oral exposure (AUC) comparable to those from the multiple dosing (3 times a day) of untreated drug. In addition, the in vivo absorption of SRSD(F6) was well-correlated with the in vitro dissolution data, establishing a good level A in vitro/in vivo correlation. These results suggest that SRSD(F6) should be promising for the sustained-release of PEL, thereby reducing the dosing frequency.

Clinical Outcomes of Adjunctive Sustained-Release Intravitreal Dexamethasone Implants in Tuberculosis-Associated Multifocal Serpigenoid Choroiditis

PURPOSE

To analyze the safety and efficacy of sustained-release intravitreal dexamethasone implant (Ozurdex) in management of TB-associated multifocal serpiginoid choroiditis (MSC).

METHODS

Retrospective review of TB-associated MSC patients, treated with anti-TB therapy (ATT) and adjunctive intravitreal Ozurdex.

RESULTS

Nine eyes of six patients were included. Four patients required Ozurdex implant for progressive or new lesions following ATT and two for additional systemic contraindications to corticosteroids - hyperglycemia and uncontrolled hypertension, respectively. The mean time to resolution was 9.17 ± 7.71 weeks. The mean follow-up post-injection was 13.11 ± 6.05 months (median 12 months [range 6-24.5 months]). Only one of nine eyes developed recurrent MSC lesions and this was attributed to possible autoimmune etiology. Two eyes (22.2%) developed steroid-induced glaucoma - one required implant removal.

CONCLUSIONS

Sustained-release intravitreal dexamethasone is a safe and efficacious adjunctive anti-inflammatory therapy for TB-associated MSC patients with contraindication for systemic corticosteroids or requiring supplemental anti-inflammatory therapy.

Preparation and evaluation of cefquinome-loaded gelatin microspheres and the pharmacokinetics in pigs

Cefquinome (CEF) is widely used for veterinary clinical applications because of its broad spectrum and high efficiency. However, frequent administrations are required due to its short elimination half-life. In this study, cefquinome sulfate gelatin microspheres (CEF-GMS) were prepared as a sustained-release formulation using emulsion chemical cross-linking technique. Physical properties, stability, sustained-release property in vitro, and pharmacokinetics in pigs were assessed. The morphology of CEF-GMS showed a good sphericity with porous structure on the surface, and the mean diameter was 8.80 ± 0.78 μm, with 90.60 ± 3.98% of the total in the range of 5-20 μm. There were no significant changes of all estimated indexes in the stability tests. In vitro drug release study showed that the release of CEF from CEF-GMS was much slower than that from crude CEF in a release medium. Pharmacokinetic characteristics were evaluated following intramuscular administration of CEF-GMS or Cefquinome sulfate injection (CEF-Inj) in pigs at a dosage of 4 mg CEF/kg body weight. The plasma drug concentration-time data of CEF-GMS and CEF-Inj were both best fitted by two-compartment models with first-order absorption, and the elimination half-life of CEF-GMS was almost 10 times that of CEF-Inj. Overall, CEF-GMS might be used as a sustained-release formulation of CEF for veterinary clinical applications.

Predicted patient demand for a new delivery system for glaucoma medicine

Sustained-release drug delivery systems that replace the need for daily glaucoma medications will improve outcomes for those who are nonadherent and reduce the inconvenience of having to take medications on a recurring basis.The objective is to estimate uptake (i.e., demand) for a new technology that delivers sustained-release glaucoma medication and to investigate how uptake varies by product attributes, physician recommendations, peer adoption (i.e., percentage of patients seen in a clinic using the new technology), and patient characteristics.In a web-enabled discrete-choice experiment survey, glaucoma patients in the United States were asked to choose between continuing eye drop use or purchasing the new delivery system. In a cross-sectional web-enabled survey, ophthalmologists were asked their likelihood of recommending the new technology based on product and patient characteristics.Study participants were 500 glaucoma patients who were on topical administration of daily eye drops and 155 ophthalmologists who practice in the US.Main outcomes were predicted uptake for patients and likelihood of recommending a new drug delivery system for ophthalmologists. Logistic models were used to analyze the choice data.Uptake was estimated to be 18% at an annual cost of $1000 and to be 24% when the cost was $500. A physician's recommendation increased uptake by 6% to 12%, whereas an increase in peer adoption from 5% to 50% increased uptake by 3% to 7%. Patients aged ≥ 65 and those with lower income were more likely to remain on eye drops. Physicians were more likely to recommend a product if the interval between administrations is 6 months or longer and when long-term safety and efficacy data are available. They were less likely to recommend it to patients with lower income and no adherence problems.Results suggest a significant interest in an injectable solution or other sustained-release alternatives to daily eye drops. However, in this survey, patient uptake was greatly influenced by out-of-pocket cost and the interval between treatment administrations. Few physicians were willing to recommend sustained-release technology if the treatment interval was less than 3 months.

Development of a sustained-release microcapsule for delivery of metoprolol succinate

Sustained-release (SR) formulations of metoprolol succinate (MS) may minimize fluctuations in plasma concentration and decrease the resulting adverse events. The aim of the present study was to optimize the loading capacity of microcapsules and the SR of MS. A uniform design method was applied to optimize the formulation of SR microcapsules, composed of ethyl cellulose and polyethylene glycol 6,000, in one step via emulsion-solvent diffusion. In vitro release was studied, and the in vivo bioavailability of MS following dosing with novel microcapsules was compared with a commercially available MS formulation in beagle dogs. The present methodology achieved an entrapment efficiency of 83.2%, with 96.1% of drug released in vitro in 18 h, and the release was close to linear over a 12-h period. Pharmacokinetic studies of MS microcapsules in beagle dogs demonstrated a superior SR profile compared with conventional SR tablets. MS microcapsules were developed with high encapsulation efficiency, which had desirable SR properties in vitro and in vivo.

Determination of anti-tuberculosis drug concentration and distribution from sustained release microspheres in the vertebrae of a spinal tuberculosis rabbit model

There have been several sustained-release materials containing anti-tuberculosis drug to enhance concentration in foci of spinal tuberculosis but what map by which composite drug delivery system is released is not known. Isoniazid (INH) lactic-co-glycolic acid (PLGA) and INH hydroxyapatite (HA) microspheres were prepared, respectively. The rabbits were modeled by tuberculosis strains and sustained-release microspheres were incubated in the foci. INH concentrations in the HA group were higher than those of INH and PLGA groups at L3, L4, and L5 vertebra 2 days after the drugs were embedded (p < 0.05). INH concentrations in the HA group were higher than those of INH and PLGA groups in L3 vertebra 4 days after the drugs were embedded (p < 0.05). INH concentrations in the PLGA group were higher than those of INH and HA groups in L5 vertebra; INH concentrations of the HA group were higher than those of INH and PLGA groups in L4 vertebra 6 days after the drugs were embedded (p < 0.05). These microspheres can enhance INH concentration in the foci. Furthermore, HA microspheres elicit osteogenic effects. HA is better than PLGA in terms of infiltration, but PLGA is better than HA in terms of distribution. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:200-208, 2017.

Sustained-release microspheres of amifostine for improved radio-protection, patient compliance, and reduced side effects

A biweekly administration of sustained-release microsphere dosage form of amifostine, a radioprotective drug used in radiotherapy, was performed to examine the feasibility to minimize injection frequency and blood concentration-associated side effects. Model animal trials indicated that this subcutaneously injecting microspheres, 50-100 μm in diameter, achieved bi-weekly prolonged radio-protective efficacy and, at the same time, significantly reduced skin irritation than the solution form of amifostine given by the same administration route. In addition, the hypertension associated with blood concentration of amifostine was not observed in the drug-treated rats. The animals given the amifostine microspheres and amifostine showed significantly differences in white blood cell, red blood cell, hematocrit, hemoglobin and spleen tissue histopathology after exposed under a cobalt-60 γ-radiation at a dose rate of 1.0 Gy/min for 6 min. The in vitro release profile of amifostine from the micropsheres showed a minor initial burst (less than 20% of total drug loading in the first day of administration), consisting with the side effects observations. The results suggest that amifostine encapsulated in sustained-release microspheres may be an ideal dosage form for prolonged radio-protective efficacy and improved patient compliance.

Antimicrobial Activity from Colistin-Heparin Lamellar-Phase Complexes for the Coating of Biomedical Devices

Infections arising in hospitalized patients, particularly those who have undergone surgery and are reliant on receiving treatment through biomedical devices, continue to be a rising concern. It is well-known that aqueous mixtures of oppositely charged surfactant and polymer molecules can self-assemble to form liquid crystalline structures, primarily via electrostatically driven interactions that have demonstrated great potential as tailored-release nanomaterials. Colistin is a re-emerging antibiotic used against multidrug-resistant Gram-negative bacteria. Its amphiphilic structure allows it to form micellar aggregates in solution. Thus, the aim of this study was to determine whether structured complexes form between colistin and negatively charged biopolymers, such as the highly sulfated anticoagulant, heparin. Cross-polarized light microscopy and synchrotron small-angle X-ray scattering were employed to visualize the appearance of birefringent structures and identify liquid crystalline structures, respectively, formed across the interface between solutions of colistin and heparin. A lamellar phase with a lattice parameter of ∼40 Å was formed upon contact between the oppositely charged solutions of colistin and heparin. In addition, in vitro release studies showed a slow release of colistin from the lamellar-phase gel complexes into the bulk media, and disk diffusion bioassays revealed antimicrobial activity against Pseudomonas aeruginosa. This system provides a novel, cost-effective, and simple approach to reducing the risk of infections by potentially applying the formulation as a coating for biomedical implants or tubing.

Implantable chemotherapy-loaded silk protein materials for neuroblastoma treatment

Neuroblastoma is the most common extracranial childhood solid tumor. Treatment of high risk tumors require intense multicycle chemotherapies, resulting in short- and long-term toxicities. Here, we present treatment of an orthotopic neuroblastoma mouse model, with silk fibroin materials loaded with vincristine, doxorubicin or the combination as a intratumoral, sustained release system. The materials, loaded with vincristine with or without doxorubicin, significantly decreased neuroblastoma tumor growth compared to materials loaded without drug or doxorubicin only as well as intravenous (IV) drug treatment. The intratumoral drug concentration was significantly higher with intratumoral delivery versus IV. Furthermore, intratumor delivery decreased the maximum plasma concentration compared to IV delivery, reducing systemic exposure and possibly reduing long-term side effects of chemotherapy exposure. Histopathologically, tumors with remission periods >25 days before recurrence transformed from a "small-round-blue cell" (SBRC) to predominantly "large cell" neuroblastoma (LCN) histopathology, a more aggressive tumor subtype with unfavorable clinical outcomes. These results show that intratumoral chemotherapy delivery may be a treatment strategy for pediatric neuroblastoma, potentially translatable to other focal tumors types. Furthermore, this treatment modality allows for a clinically relevant mouse model of tumor transformation that may be used for studying the phenotypical tumor recurrence and developing more effective treatment strategies for recurrent tumors.