Advance in Nanomedicine for Improving Mucosal Penetration and Effective Therapy of Cervical Cancer.

Insufficient intratumor drug distribution and serious adverse effects are often associated with systemic chemotherapy for cervical cancer. Considering the location of cervical cancer, access to the cervix through the vagina may provide an alternative administration route for high drug amounts at the tumor site, minimal systemic exposure as well as convenience of non-invasive self-medication. Enormous progress has been made in nanomedicine to improve mucosal penetration and enhance the effectiveness of therapy for cervical cancer. This review article first introduce the physiological state of cervicovaginal cavity and the characteristics of intravaginal environment in cervical cancers. Based on introduction to the physiological state of cervicovaginal cavity and the characteristics of intravaginal environment in cervical cancers, both "first mucus-adhering then mucosal penetration" and "first mucus-penetrating then mucosal penetration" strategies are discussed with respect to mechanism, application condition, and examples. Finally, existing challenges and future directions are envisioned in the rational design, facile synthesis, and comprehensive utilization of nanomedicine for local therapy of cervical cancer. This review is expected to provide useful reference information for future research on nanomedicine for intravaginally administered formulations for topical treatment of cervical cancer.

Preparation and In Vitro and In Vivo Evaluation of a Testosterone Film Forming Gel for the Treatment of Hypoactive Sexual Desire Disorder in Women.

Hypoactive sexual desire disorder (HSDD) is one of the most common sexual complaints in women. Currently, there is an unmet need for a drug treatment for this disorder. The purpose of this study was to develop a testosterone (TS) film forming gel used for women to treat HSDD by measuring the tackiness, peel adhesion force, tensile strength, and elasticity of the formulation. Diethylene glycol monoethyl ether (Transcutol P), an efficient penetration enhancer, was added to the optimized formulation and the transdermal permeation characteristics in vitro were studied using Franz-diffusion cells. The quantitative determination of TS was performed by high-performance liquid chromatography (HPLC). After 24 h, Transcutol P at 3% had the largest cumulative amount of drug and enhancement ratio of TS of 75.14 µg/cm2 and 2.82, respectively. After the screening of film forming polymers and penetration enhancers, the optimal formulation was as follows: glycerol (1%, w/w); 12.5% sodium carboxymethylcellulose (CMC-Na) aqueous solution (0.5%, w/w); 2.5% Carbomer ethanol solution (0.5%, w/w); Transcutol P ethanol solution (3%, w/w) containing 0.5% TS; and 8% Poly vinyl alcohol (PVA) aqueous solution (30%, w/w). The optimized film forming gel had good uniformity and the release of TS in vitro was close to 100% within 24 h. In vivo studies showed the formulations had optimal area under blood drug concentration curve values in the order of 3% Transcutol P > 1% Transcutol P > 5% Transcutol P > control preparation. The formulation with 3% Transcutol P provided the highest permeation effect both in vitro and in vivo. The safety of this formulation was further evaluated with a skin irritation test. It could effectively improve the rabbit skin irritation observed with a marketed transdermal patch Androderm®. The present study provides a promising approach for the development of a novel TS film forming gel for the treatment of HSDD in women.

Physical-Chemical Characterization of Octreotide Encapsulated in Commercial Glucose-Star PLGA Microspheres.

Sandostatin LAR (SLAR) is an injectable long-acting release (LAR) microsphere formulation for octreotide based on a biodegradeable glucose star copolymer of d,l-lactic and glycolic acids (PLGA-glu), which is primarily used for the treatment of patients with acromegaly. There currently is no generic SLAR approved in the United States despite expiration of patent coverage. To understand better this important formulation, SLAR was assessed for its composition and physical-chemical properties. Octreotide release kinetics was monitored under physiological conditions over 56 days together with several bioerosion parameters [mass loss, water uptake, pH of release media, polymer molecular weight (Mw), and confocal microscopy after BODIPY uptake]. A significant increase in the amount of released peptide occurred after day 14. After 1 day of incubation in PBST, octreotide was not extractable completely from SLAR during 2 h of the extraction process, but complete extraction was accomplished after 24 h, which suggested that strong and noncovalent PLGA-octreotide interactions occurred beginning in the initial release phase. Leuprolide is considered as a cationic peptide competitor for octreotide-PLGA interactions and its presence in the release medium resulted in more continuous octreotide release from SLAR, which was linearly correlated with the mass loss from the polymer (i.e., an indication of erosion-controlled release). These data strongly suggest that octreotide forms a salt with acid end groups of linear PLGA chains that are either present as impurities in, and/or produced by the degradation of, the PLGA-Glu. This salt is expected to catalyze octreotide acylation and extend peptide release beyond that driven by erosion control. The characterization studies of physicochemical properties of SLAR described here could be useful for the development and regulatory evaluation of generic octreotide microspheres as well as new polymer formulations, in which the polymer strongly interacts with encapsulated peptides.

Empirical prediction model based process optimization for droplet size and spraying angle during pharmaceutical fluidized bed granulation.

The objective of this study was to predict the droplet size and the spraying angle during the process of binder atomization in pharmaceutical fluidized bed granulation using an empirical model. The effects of the binder viscosity, the atomization pressure, and the spray rate on the droplet size and the spraying angle were investigated using a response surface central composite design and analysis of variance. Prediction models for droplet size and spraying angle were then established using stepwise regression analysis and were validated by comparing the measured and predicted values. The results showed that the droplet size model and the spraying angle model were well established, with an R2 of 0.93 (p < 0.0001) and a root mean square error (RMSE) of 10.10, and an R2 of 0.82 (p < 0.0001) and an RMSE of 3.69, respectively. The error between the measured and predicted values of the droplet size and the spraying angle were less than 10%, indicating that the established models were accurate. The results of the present study were significant in predicting the droplet size and spraying angle in the process of pharmaceutical fluidized bed granulation.

[Modification by wheat germ agglutinin delays the ocular elimination of liposome].

The purpose of this study is to explore the feasibility of wheat germ agglutinin (WGA) modified liposome as a vehicle for ophthalmic administration. Liposome loaded with 5-carboxyfluorescein (FAM) was prepared by lipid film hydration method. WGA was thiolated and then conjugated to the surface of the liposome via polyethylene glycol linker to constitute the WGA-modified and FAM-loaded liposome (WGA-LS/FAM). The amount of thiol groups on each WGA molecule was determined, and the bioactivity of WGA was estimated after it was modified to the surface of liposome. The physical and chemical features of the WGA-modified liposome were characterized and the ocular bioadhesive performance was evaluated in rats. The result showed that each thiolated WGA molecule was conjugated with 1.32 thiol groups. WGA-LS/FAM had a mean size of (97.40 +/- 1.39) nm, with a polydispersity index of 0.23 +/- 0.01. The entrapment efficacy of FAM was about (2.95 +/- 0.21)%, and only 4% of FAM leaked out of the liposome in 24 h. Erythrocyte agglutination test indicated that after modification WGA preserved the binding activity to glycoprotein. The in vivo ocular elimination of WGA-LS/FAM fitted first-order kinetics, and the elimination rate was significantly slower than that of the unmodified liposome, demonstrating WGA-modified liposome is bioadhesive and suitable for ophthalmic administration.

Evaluation the injectability of injectable microparticle delivery systems on the basis of injection force and discharged rate.

BACKGROUND: Subcutaneous injection of biopharmaceutical agents or microparticles is challenging due to issues with low injection efficiency and high residual amounts. OBJECTIVE: This study aimed to determine the important factors affecting the injectability of microparticle delivery systems, establish a suitable injection system with lower injection force and higher discharge rate, and eventually develop a reliable injectability evaluation system for injectable microparticle delivery systems in vitro and in vivo. METHODS: The effects of various parameters, including particle size, injection speed, concentration of microspheres suspension, vehicle viscosity, needle length and gauge were evaluated by measuring the injection force and discharge rate. The characteristics of microparticles and rheological measurement of the suspension systems were studied. A design of experiment approach was utilized to evaluate the interaction between the microsphere suspension, vehicle viscosity and needle gauges. Both in vitro sieve tests and in vivo tests in rats were conducted to evaluate injectability. RESULTS: The in vitro test results showed that the vehicle viscosity and injection speed have varying effects on discharge rate and injection force, respectively. Particle size and needle gauge have substantial influence on injectability, larger particle size and smaller needle gauges resulting in poor injectability, while the needle gauge was found to have the greatest influence on injectability. Levonorgestrel (LNG) microsphere and glass bead were relatively uniform spherical, the glass bead had extremely smooth surface; while mesoporous silica had irregular shape. The settling rate of glass bead was the fastest, which was about 18 times faster than the LNG microsphere. The CMC-Na had a poor interaction with the LNG microspheres, glass bead and mesoporous silica and showed basically Newtonian behavior in the shear rate range of 0.1 s-1-100 s-1. When shear rate increased to more than 100 s-1, no obvious shear thinning behavior was observed. CMC-Na formed a nodule structure with whether LNG microspheres or the glass beads, which were much lower than that with the mesoporous silica in static state, among which the glass beads were the weakest. The viscosity of the suspension increased with the rising of the volume fraction of particles. Fundamentals of hydrodynamics in capillaries were referenced, such as Navier-Stokes Law equation, Krieger-Dougherty (K-D) equation, Hagen-Poiseuille equation. The best results achieved was using a suspension concentration of 120-240 mg /mL and a viscosity of 60 cP at 20 °C with 23-gauge needles. The optimized conditions were verified in vivo tests. It was proven that the LNG microsphere suspension had a good injectability when injected into subcutaneous tissue of rats. CONCLUSION: The injection system of injectable microparticle delivery system with lower injection force and higher discharge rate was established and the evaluation method was suitable for the injectability evaluation both in vivo and in vitro. Improved injectability would promote the clinical translation of microparticle delivery systems.

Correction: Ci et al. Enhanced Delivery of Imatinib into Vaginal Mucosa via a New Positively Charged Nanocrystal-Loaded in Situ Hydrogel Formulation for Treatment of Cervical Cancer. Pharmaceutics 2019, 11, 15.

In the original publication [...].

Correction to "Folic acid-conjugated liposomal vincristine for multidrug resistant cancer therapy".

[This corrects the article DOI: 10.1016/j.ajps.2013.07.015.].

Development and characterization of composition-equivalent formulations to the Sandostatin LAR® by the solvent evaporation method.

Sandostatin long-acting release® (SLAR) is a long-acting injectable somatostatin analogue formulation composed of octreotide encapsulated in glucose-initiated poly(lactic-co-glycolic acid) (PLGA) microspheres. Despite the end of patent protection, SLAR remains resistant to generic competition likely due to complexity of production process, the uniqueness of the glucose star polymer, and the instability of octreotide in the formulation. Here, we describe development of glucose-PLGA-based composition-equivalent to SLAR formulations prepared by double emulsion-solvent evaporation method and the effect of variations in encapsulation variables on release kinetics and other formulation characteristics. The following encapsulation variables were adjusted at constant theoretical loading of 7.0% peptide: PLGA concentration, pH of inner water phase, and stirring rate. After final drying, the microspheres were examined with and without annealing at 50 °C under vacuum for 3 days. The loading and encapsulation efficiency (EE) of octreotide acetate, manufacturing yield, and in vitro drug release kinetics in PBStc (10 mM phosphate-buffered saline (PBS) with 1% triethyl citrate and 0.02% sodium azide at pH 7.4) were determined by UPLC. The in vitro release and acylation kinetics of octreotide for the solvent evaporation formulations prepared were similar to SLAR although the initial burst was slightly higher. Key formulation steps identified to maximize microsphere yield and minimize residual solvent and initial burst release included (a) addition of acetic acid to the peptide before preparation and (b) annealing the microspheres under vacuum after drying. Controlled release octreotide formulations prepared and investigated in this study could provide a better understanding of the effect of production variables on release performance and supply information useful for making progress in manufacturing of SLAR generic equivalents.

LyP-1-conjugated doxorubicin-loaded liposomes suppress lymphatic metastasis by inhibiting lymph node metastases and destroying tumor lymphatics.

Lymphatic metastasis can be greatly promoted by metastases growth and lymphangiogenesis in lymph nodes (LNs). LyP-1, a cyclic peptide, is able to specifically bind with tumor cells and tumor lymphatics in metastatic LNs. This work aimed to use LyP-1-conjugated liposomes (L-LS) loaded with doxorubicin (DOX) (L-LS/DOX) to suppress lymphatic metastasis by inhibiting both metastases and tumor lymphatics in LNs. L-LS were prepared and exhibited sizes around 90 nm and spherical morphology as characterized by transmission electron microscopy. The in vitro cellular studies showed that LyP-1 modification obviously increased liposome uptake by MDA-MB-435 tumor cells and enhanced the cytotoxicity of liposomal DOX. A popliteal and iliac LN metastases model was successfully established by subcutaneous inoculation of tumor cells to nude mice. The immunofluorescence staining analysis indicated that LyP-1 modification enabled specific binding of liposome with tumor lymphatics and enhanced the destroying effect of liposomal DOX on tumor lymphatics. The in vivo fluorescence imaging and pharmacodynamic studies showed that LyP-1 modification increased liposome uptake by metastatic LNs and that L-LS/DOX significantly decreased metastatic LN growth and LN metastasis rate. These results suggested that L-LS/DOX were an effective delivery system for suppressing lymphatic metastasis by simultaneously inhibiting LN metastases and tumor lymphatics.

Inhibitory potential of chlormadinone acetate (CMA) on five important UDP-glucuronosyltransferases in human liver.

Chlormadinone acetate (CMA), a derivative of 17-a-hydroxyprogesterone, has been widely used as an orally effective progestogen in hormone replacement therapy (HRT). Glucuronidation catalyzed by UDP-glucuronosyltransferases (UGTs) is one of the major steps responsible for the metabolism of many drugs, environmental chemicals and endogenous compounds. Pharmacokinetic behaviours of drugs could be altered by inhibition of these UGT isoforms, and the search for drugs that potentially inhibit these UGT isoforms is very significant from a clinical point of view. In the present study, inhibition of five important UGT isoforms in human liver (UGT1A1, 1A3, 1A6, 1A9 and 2B7) by CMA was investigated using 4-MU as nonspecific substrate and recombinant UGT isoforms as enzyme sources. The results showed that CMA exhibited inhibitory effects on UGT1A3 (IC50 = 8.6 +/- 1.4 microM) and UGT2B7 (IC50 = 14.2 +/- 3.8 microM), with other UGT isoforms negligibly influenced. Lineweaver-Burk and Dixon plots showed that CMA noncompetitively inhibited UGT1A3 and UGT2B7. The Ki value was calculated to be 36.9 microM and 4.1 microM for UGT1A3 and UGT2B7, respectively. Considering that UGT1A3 and UGT2B7 are involved in the metabolism of many drugs, special attentions should be paid when CMA was co-administered with the drugs which mainly underwent UGT1A3, 2B7-mediated metabolism.

Enhanced mucosal penetration and efficient inhibition efficacy against cervical cancer of PEGylated docetaxel nanocrystals by TAT modification.

To investigate the potential of cell penetrating peptide (CPP) modification on nanomedicine for improving mucosal penetration and effective therapy of cervical cancer, docetaxel nanocrystals modified with trans-activator of transcription (TAT) peptide were designed for treatment of cervical cancer via vaginal administration. Docetaxel nanocrystals were coated by polymerization of dopamine to form polydopamine (PDA) coating which facilitated TAT modification and PEGylation for less mucus entrapment to get PEGylated nanocrystals modified with TAT (NC@PDA-PEG-TAT). Enhanced cellular drug uptake and cytotoxicity of NC@PDA-PEG-TAT was observed in cervical cancer-related TC-1 cells than that of PEGylated nanocrystals (NC@PDA-PEG). Intravaginally administered NC@PDA-PEG-TAT dispersed in poloxamer 407-based thermosensitive gel exhibited prolonged in vivo intravaginal retention, deeper mucosal penetration and more potent inhibition on the growth of murine orthotopic cervical cancer than NC@PDA-PEG, PDA-coated nanocrystals or unmodified nanocrystals. All data suggested the significance of CPP-modification on nanocrystals in the local treatment of vaginal mucosa-related diseases by vaginal administration.

siRNA-based breast cancer therapy by suppressing 17ß-hydroxysteroid dehydrogenase type 1 in an optimized xenograft cell and molecular biology model in vivo.

PURPOSE: Hormone-dependent breast cancer is the most common form of breast cancer, and inhibiting 17ß-HSD1 can play an attractive role in decreasing estrogen and cancer cell proliferation. However, the majority of existing inhibitors have been developed from estrogens and inevitably possess residual estrogenicity. siRNA knockdown provides a highly specific way to block a targeted enzyme, being especially useful to avoid estrogenicity. Application of 17ß-HSD1-siRNA in vivo is limited by the establishment of an animal model, as well as the potential nuclease activity in vivo. We tried to reveal the in vivo potential of 17ß-HSD1-siRNA-based breast cancer therapy. MATERIALS AND METHODS: To establish a competent animal model, daily subcutaneous injection of an estrone micellar aqueous solution was adopted to provide the substrate for estradiol biosynthesis. The effects of three different doses of estrone (0.1, 0.5, and 2.5 µg/kg/day) on tumor growth in T47D-17ß-HSD1-inoculated group were investigated and compared with the animals inoculated with wild type T47D cells. To solve in vivo delivery problem of siRNA, "17ß-HSD1-siRNA/LPD", a PEGylated and modified liposome-polycation-DNA nanoparticle containing 17ß-HSD1-siRNA was prepared by the thin film hydration method and postinsertion technology. Finally, "17ß-HSD1-siRNA/LPD" was tested in the optimized model. Tumor growth and 17ß-HSD1 expression were assessed. RESULTS: Comparison with the untreated group revealed significant suppression of tumor growth in "17ß-HSD1-siRNA/LPD"-treated group when HSD17B1 gene expression was knocked down. CONCLUSION: These findings showed promising in vivo assessments of 17ß-HSD1-siRNA candidates. This is the first report of an in vivo application of siRNA for steroid-converting enzymes in a nude mouse model.

Fenofibrate modified-release pellets with lag phase and high oral bioavailability.

PURPOSE: Fenofibrate and statin combination therapy is highly recommended by the current clinical guidelines for treatment of mixed dyslipidemia. In this study, an innovative delayed-release preparation of fenofibrate was designed to reduce the risk of muscle toxicity, caused by simultaneous administration of this combination therapy, by altering the pharmacokinetic profile of fenofibrate, as well as to improve the oral bioavailability of the modified-release formulation. METHODS: Micronized fenofibrate was used to prepare drug-loaded cores via a powder layering process before multiparticulate pellet coating. Different coating formulations (Eudragit® RS PO/E100, Eudragit® RS PO/RL PO, Eudragit® NE30D/HPMC, and EC/HPMC) were screened, and their in vitro release was compared with the commercial sustained-release pellets Lipilfen®. Two optimized formulations were evaluated in beagle dogs using two commercial preparations of fenofibrate (the immediate-release preparation Lipanthyl® and the sustained-release pellets Lipilfen®) as references. RESULTS: The in vivo release of fenofibrate from R1 and R2 selected from in vitro tests exhibited a lag phase, and then rapid and complete drug release. The relative bioavailabilities of R1 and R2 were 100.4% and 201.1%, respectively, which were higher than that of Lipilfen® (67.2%). CONCLUSION: The modified fenofibrate pellets developed showed enhanced bioavailability and delayed-release properties. They have the potential to improve safety and compliance when co-administrated with statins. This is the first report of a delayed-release fenofibrate preparation.

Enhanced Delivery of Imatinib into Vaginal Mucosa via a New Positively Charged Nanocrystal-Loaded in Situ Hydrogel Formulation for Treatment of Cervical Cancer.

The present study was carried out to investigate the potential of cationic functionalization on imatinib nanocrystals to improve the mucoadhesiveness and, thus, delivery to the lesion of cervicovaginal tumors. Amino-group-functionalized imatinib nanocrystals (NC@PDA-NH2) were prepared with near-spheroid shape, nanoscale size distribution, positive zeta potential, and relatively high drug content with the aid of the polydopamine-coating technique. Efficient interaction between NC@PDA-NH2 and mucin was proven by mucin adsorption which was related to the positive zeta-potential value of NC@PDA-NH2 and the change in the size distribution on mixing of NC@PDA-NH2 and mucin. Cellular uptake, growth inhibition, and apoptosis induction in cervicovaginal cancer-related cells demonstrated the superiority of NC@PDA-NH2 over unmodified nanocrystals. For practical intravaginal administration, NC@PDA-NH2 was dispersed in Pluronic F127-based thermosensitive in situ hydrogel, which showed suitable gelation temperature and sustained-release profiles. In comparison with unmodified nanocrystals, NC@PDA-NH2 exhibited extended residence on ex vivo murine vaginal mucosa, prolonged in vivo intravaginal residence, and enhanced inhibition on the growth of murine orthotopic cervicovaginal model tumors indicated by smaller tumor size, longer median survival time, and more intratumor apoptosis with negligible mucosal toxicity. In conclusion, cationic functionalization endowed NC@PDA-NH2 significant mucoadhesiveness and, thus, good potential against cervicovaginal cancer via intravaginal administration.

Current knowledge and development of hederagenin as a promising medicinal agent: a comprehensive review.

Hederagenin (HG) is a pentacyclic triterpenoid that exists in many plants in the form(s) of sapogenin or saponins. This review highlights the pharmacokinetics, pharmacological activities, mechanisms of action, and safety of HG using literature and patents from the last 50 years to collate information on this compound as a promising medicinal agent. This review also looks at the development of related derivatives of HG with increased efficacy and lower toxicity. HG is quickly absorbed in the gastrointestinal tract with a short elimination half-life, and can cross the blood-brain barrier and rapidly distribute into cerebrospinal fluid. HG has been shown to possess a wide range of pharmacological activities, including anti-tumor, anti-inflammatory, anti-depressant, anti-neurodegenerative, anti-hyperlipidemia, anti-diabetic, anti-leishmanial, and anti-viral activity. In particular, the extensive anti-tumor activity indicates that HG has the potential to be a highly effective chemotherapy agent. Recently, in the search for more active compounds as potential pharmaceuticals, structural modification of the triterpene scaffold of HG at the C-3, C-12, C-13, C-23, and C-28 positions, has resulted in compounds that exhibited greater potency than HG itself. However, the low bioavailability and moderate hemolysis effect of HG may limit its clinical application. The cause of the observed toxic effects in some animals, including dogs, cats, cattle, goats, and horses also needs to be explained. Future studies of HG focusing on extending the half-life, improving bioavailability, enhancing pharmacological activity, as well as decreasing or avoiding hemolysis by structural modification or formulation design could potentially accelerate HG from the preclinical to clinical research phase.

An Injectable Thermogel Containing Levonorgestrel for Long-Acting Contraception and Fertility Control of Animals.

The demand of contraception and fertility control of animals is huge in livestock field and pet market. In this study, we suggest a formulation made up of an injectable and biodegradable thermogel for sustained delivery of levonorgestrel (LNG), a hormonal contraceptive, to realize the long-acting animal contraception. A thermogelling poly(lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) triblock copolymer was synthesized in a one-pot reaction. The micelles formed by the amphiphilic polymer carriers in water could serve as a reservoir for the solubilization of hydrophobic LNG molecules. The concentrated polymer aqueous solution exhibited a reversible sol-gel transition upon heating, and the incorporation of various amounts of LNG was found not to affect the thermogelation of the polymer/water system. In vitro release profiles showed that the entrapped LNG was sustainedly released from the thermogel matrix and the initial drug-loading amounts had a significant influence on the release kinetics of LNG. In vivo pharmacokinetic studies demonstrated that the use of PLGA-PEG-PLGA thermogel markedly extended the release of LNG after subcutaneous injection into SD rats. Consequently, this study revealed that the injectable PLGA-PEG-PLGA thermogel was a promising candidate for sustained delivery of LNG, and provided an attractive option for long-term contraception and fertility control of animals by a way of facile fabrication, easy administration and low expense.

A novel penetratin-modified complex for noninvasive intraocular delivery of antisense oligonucleotides.

Inhibition of gene expression by nucleic acids is a promising strategy in the treatment of ocular diseases. However, intraocular delivery of nucleic acids to the posterior ocular tissues remains a great challenge due to the presence of various biological barriers. To circumvent this problem, we established a novel penetratin (P) modified poly(amidoamine) dendrimer (D)/hyaluronic acid (H) complex to deliver antisense oligonucleotides (ASOs, O). Complexes (D/O, HD/O and PHD/O) were easily prepared and modification layers (hyaluronic acid and penetratin) were respectively absorbed on the surface via electrostatic interaction. Complexes with different outer layers were characterized as spherical particles with reversed charges. In vitro cellular uptake of ASOs in PHD/O complex was significantly increased than those in other formulations. In vivo studies were carried out after topical instillation of the complexes in the conjunctival sac of mice. Compared with D/O and HD/O, PHD/O exhibited much more distribution in the posterior segment of the eyes and prolonged retention time of ASOs in retina for more than 8h. Taken together, these results indicated that PHD/O complex possessed substantially improved ocular permeability and distribution in the posterior ocular tissues. This work provided a promising noninvasive intraocular delivery strategy for nucleic acids via topical administration.

In vivo retention of poloxamer-based in situ hydrogels for vaginal application in mouse and rat models.

The purpose of this study is to evaluate the in vivo retention capabilities of poloxamer-based in situ hydrogels for vaginal application with nonoxinol-9 as the model drug. Two in situ hydrogel formulations, which contained 18% poloxamer 407 plus 1% poloxamer 188 (GEL1, relative hydrophobic) or 6% poloxamer 188 (GEL2, relative hydrophilic), were compared with respect to the rheological properties, in vitro hydrogel erosion and drug release. The vaginal retention capabilities of these hydrogel formulations were further determined in two small animal models, including drug quantitation of vaginal rinsing fluid in mice and isotope tracing with 99mTc in rats. The two formulations exhibited similar phase transition temperatures ranging from 27 to 32 °C. Increasing the content of poloxamer 188 resulted in higher rheological moduli under body temperature, but slightly accelerated hydrogel erosion and drug release. When compared in vivo, GEL1 was eliminated significantly slower in rat vagina than GEL2, while the vaginal retention of these two hydrogel formulations behaved similarly in mice. In conclusion, increases in the hydrophilic content of formulations led to faster hydrogel erosion, drug release and intravaginal elimination. Rats appear to be a better animal model than mice to evaluate the in situ hydrogel for vaginal application.