Characterization of a female controlled drug delivery system for microbicides

Drug formulations for localized treatment of Human Papillomavirus-induced lesions

BACKGROUND

The human papillomavirus (HPV) is responsible for over 90% of all cervical cancer cases. The use of vaginal gels is often indicated for local vaginal drug delivery. Previous studies have shown that Thymus vulgaris essential oil (TEO) exhibits anticancer properties besides antifungal and antibacterial properties. Its activity derives from a specific increase in free radicals and oxidative stress caused in cancer cells. Furthermore, mitoxantrone (MTX), an anthracenedione and C₈, an acridine orange derivative, were shown to inhibit the growth of the cervical cancer cell line HeLa.

RESULTS

The results showed that TEO + C₈ is the most promising formulation in terms of viscosity and osmolality properties in vaginal fluid simulant (VFS). The combined action of TEO with the compound's MTX and C₈ resulted in HeLa cell viability reduction compared with the effect obtained with the individual formulations containing each one of the compounds.

CONCLUSIONS

The formulation TEO + C₈ holds promise in terms of cost-benefit and topical application of the active compound for the HeLa cells.

Physicochemical Evaluation and Pharmacodynamics of Itraconazole-loaded Liquid Crystal Precursor for Vaginal Delivery

PURPOSE

To develop liquid crystal (LC) precursor that can be used as a novel vaginal delivery system for Itraconazole (ITZ) and evaluate its pharmacodynamics. Methods: The LC precursor was prepared by using phytantriol (PYT) as lipid matrix and N, N-dimethylformamide (DMAC) as solvent. Swelling studies were performed to assess the phase conversion ability. The formulations were characterized by crossed polarized light microscopy (CPLM), small-angle X-ray scatterin (SAXS). Moreover, the rheological and in vitro drug release behavior were investigated. Then the vaginal retention time of ITZ in the optimal prescription was evaluated. Finally, the pharmacodynamics studies of the ITZ-loaded LC precursor were performed in a mouse model of vulvovaginal candidiasis (VVC). Results: The LC precursor could transform to LC gels after administration into the vagina. Based on PLM and SAXS, the LC gels, formed after phase-conversion, were cubic LC. The LC precursor was Non-Newtonian, while the LC gels exhibited a pseudo-plastic fluid behavior. In vitro release results revealed that F2 (68.0 %) had a higher cumulative drug release than that of F1 (59.17 %) at 72 h. Most of the LC gels could be retained in the vagina of mice for 24 - 36 h. Pharmacodynamics studies showed that there was only mild inflammation or no inflammatory stimulation in the control group. The ITZ-loaded LC precursor significantly improved the symptoms of vaginitis in mice and had a better therapeutic effect than that of positive control group. Conclusions: The ITZ-loaded LC precursor would be a promising formulation for vaginal drug delivery.

Development and characterization of chitosan nanoparticles loaded nanofiber hybrid system for vaginal controlled release of benzydamine

Vaginal infections caused by various pathogens such as fungi, viruses and protozoa are frequently seen. Systemic and local treatments can be applied to eliminate these infections. Novel vaginal drug delivery systems can be used to provide local treatment. Vaginal drug delivery systems prevent systemic side effects and can provide long-term drug release in the vaginal area. Nanofibers and nanoparticles have a wide range of applications and can also be preferred as vaginal drug delivery systems. Benzydamine is a non-steroidal anti-inflammatory and antiseptic drug which is used for treatment of vaginal infections. The aim of this study was to compare the nanofiber and gel formulations containing lyophilized benzydamine nanoparticles with nanofiber and gel formulations containing free benzydamine, and to provide prolonged release for protection from the vaginal infections. Ionic gelation method was used for the preparation of benzydamine loaded nanoparticles. To produce benzydamine nanoparticles loaded nanofiber formulations, polyvinylpyrrolidone (PVP) solutions were prepared at 10% concentrations and mixed with nanoparticles. Hydroxypropyl methylcellulose (HPMC) was used as a gelling agent at the concentration of 1% for the vaginal gel formulation. Nanoparticles were characterized in terms of zeta potential, polydispersity index and particle size. Viscosity, surface tension and conductivity values of the polymer solutions were measured for the electrospinning. Mechanical properties, contact angle and drug loading capacity of the fibers were determined. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), fourier-transform infrared (FT-IR) spectroscopy, mucoadhesion, ex vivo permeability studies and in vitro release studies were performed for the selected formulations. Ex vivo permeability studies were performed using Franz diffusion cell method. SEM and TEM images showed that fiber diameters increased with loading of nanoparticles. DSC studies showed no interaction between excipients used in the formulation. Tensile strength and elongation at break values of the fibers increased with the loading of nanoparticles, and the contact angle values of the fibers were found to be 0°. Addition of benzydamine nanoparticles to gel and nanofiber formulations increased mucoadhesion compared to free benzydamine loading formulations. Benzydamine nanoparticle loaded gel and nanofiber formulations penetrated slower than that of free benzydamine gel and fiber formulations. The results demonstrated that benzydamine and benzydamine nanoparticle loaded fibers and gels could be a potential drug delivery system for the treatment of vaginal infections. Chitosan nanoparticle loaded nanofiber formulations are offered as an alternative controlled release vaginal formulations for vaginal infections.

A vaginal drug delivery model

Efficient drug delivery at vaginal cavity is often a challenge owing to its peculiar physiological variations including vast differences in pH. Keeping in view this attribute of the target site, the current work was aimed at developing formulation strategies which could overcome this and successfully deliver molecules like itraconazole through SLNs. Optimized SLNs with the given composition was selected for further development into mucoadhesive and thermosensitive gel. Stearic acid and Compritol 888 (1:1, w/w ratio) as lipid, a mixture of 3% Poloxomer 188 and 0.5% sodium taurocholate as surfactant and organic to aqueous ratio of 10:50 was taken. Carbopol 934 and Pluronic F 127 were taken for the development of gel. Optimized gel exhibited a desired gelling temperature (35 °C); viscosity (0.920 PaS) and appreciable in vitro drug release (62.2% in 20 h). MTT assay did not show any cytotoxic effect of the gel. When evaluated in vivo, it did not exhibit any irritation potential despite appreciable bioadhesion. A remarkable decrease in CFUs was also observed in comparison with control and marketed formulation when evaluated in rat infection model. Thus, the proposed study defines the challenges for developing a suitable formulation system overcoming the delivery barriers of the vaginal site.

Preparation and characterization of bioadhesive controlled-release gels of cidofovir for vaginal delivery

The aim of this study was to develop mucoadhesive and thermosensitive gels for vaginal delivery that would be able to provide a controlled release of the model drug, cidofovir. The study also monitored the drug's potential antiviral properties. Cidofovir was put into the form of a vaginal gel, using mucoadhesive and thermosensitive polymers such as chitosan, Carbopol 974P, HPMC, and poloxamer 407. The physicopharmaceutical properties and stability of the vaginal gel formulations were evaluated. The gel formulation which was prepared with HPMC K100M exhibited the highest viscosity, as well as maximum adhesiveness, cohesiveness, and mucoadhesion values. The results of antiviral activity studies, which used the bovine herpes virus type 1 virus infection in vitro model using Vero cells, demonstrated the antiherpetic effect of the cidofovir gel containing HPMC K100M, at least under in vitro conditions. The study found that a mucoadhesive vaginal gel containing cidofovir can be a promising and innovative alternative therapeutic system for the treatment of genital herpes simplex virus and human papilloma virus induced infections in women.

Recent advances on anti-HIV vaginal delivery systems development

A review of the recent outcomes regarding technologies to prevent vaginal transmission of HIV, mainly by using antiretroviral (ARV) drugs formulated as microbicides. An introduction about the HIV transmission mechanisms by the vaginal route is included, together with the recent challenges faced for development of successful microbicide products. The outcomes of clinical evaluations are mentioned, and the different formulation strategies studied to-date, with the requirements, advantages, disadvantages and limitations of each dosage-form type, are presented. Finally, the recent attempts to apply various types of nanotechnologies in order to develop advanced microbicide-products and overcome existing limitations, are discussed.

Surface tension in human pathophysiology and its application as a medical diagnostic tool

Introduction: Pathological features of disease appear to be quite different. Despite this diversity, the common feature of various disorders underlies physicochemical and biochemical factors such as surface tension. Human biological fluids comprise various proteins and phospholipids which are capable of adsorption at fluid interfaces and play a vital role in the physiological function of human organs. Surface tension of body fluids correlates directly to the development of pathological states.

Methods: In this review, the variety of human diseases mediated by the surface tension changes of biological phenomena and the failure of biological fluids to remain in their native state are discussed.

Results: Dynamic surface tension measurements of human biological fluids depend on various parameters such as sex, age and changes during pregnancy or certain disease. It is expected that studies of surface tension behavior of human biological fluids will provide additional information and might become useful in medical practice. Theoretical background on surface tension measurement and surface tension values of reference fluids obtained from healthy and sick patients are depicted.

Conclusion: It is well accepted that no single biomarker will be effective in clinical diagnosis. The surface tension measurement combined with routine lab tests may be a novel non-invasive method which can not only facilitate the discovery of diagnostic models for various diseases and its severity, but also be a useful tool for monitoring treatment efficacy. We therefore expect that studies of surface tension behavior of human biological fluids will provide additional useful information in medical practice.

LIPOSOMAL GELS FOR VAGINAL DELIVERY OF THE MICROBICIDE MC-1220: PREPARATION AND IN VIVO VAGINAL TOXICITY AND PHARMACOKINETICS

MC-1220 is a highly potent and selective non-nucleoside reverse transcriptase inhibitor (NNRTI) of HIV. The objective is to develop formulations for the vaginal delivery of MC-1220 and characterize them in vitro and in vivo (drug uptake, pharmacokinetics, toxicokinetics and vaginal irritation/inflammation). Due to the low aqueous solubility of MC-1220, emulsion-type and liposomal formulations of MC-1220 were developed. After rheological property adjustment (by gelling agents), the toxicity of two types of vaginal formulations of MC-1220 (emulsion [E] and liposomal [LIP] formulations) at 0.1% (E and LIP) and 0.5% (LIP) drug concentration, towards the vaginal mucosa as well as the absorption of the drug through the vaginal epithelium were investigated, after single and multiple administrations in New Zealand white NZW rabbits, for 10 days. Vaginal irritation was found to be within the acceptable range and always lower compared to the irritation caused by positive control formulation (nonoxynol-9), for all the formulation types (and concentrations evaluated). Pharmacokinetic values measured showed that the 0.1% LIP formulation was faster and better absorbed compared to the similar concentration E formulation, although most differences were not significant due to high variations. In conclusion, both types of formulations can be considered as safe for prolonged vaginal administration of MC-1220 or other drugs.

Characterization of the adherence properties of human Lactobacilli strains to be used as vaginal probiotics

In the present work, the adhesion of 43 human lactobacilli isolates to mucin has been studied. The most adherent strains were selected, and their capacities to adhere to three epithelial cell lines were studied. All intestinal strains and one vaginal isolate adhered to HT-29 cells. The latter was the most adherent to Caco-2 cells, although two of the intestinal isolates were also highly adherent. Moreover, five of the eight strains strongly adhered to HeLa cells. The binding of an Actinomyces neuii clinical isolate to HeLa cells was enhanced by two of the lactobacilli and by their secreted proteins, while those of another two strains almost abolished it. None of the strains were able to interfere with the adhesion of Candida albicans to HeLa cells. The components of the extracellular proteome of all strains were identified by MALDI-TOF/MS. Among them, a collagen-binding A precursor and aggregation-promoting factor-like proteins are suggested to participate on adhesion to Caco-2 and HeLa cells, respectively. In this way, several proteins with LysM domains might explain the ability of some bacterial supernatants to block A. neuii adhesion to HeLa cell cultures. Finally, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) could explain the good adhesion of some strains to mucin.

Topical nonnucleoside reverse transcriptase inhibitor MC 1220 partially prevents vaginal RT-SHIV infection of macaques

The availability of an effective vaginal microbicide would be a major step toward containment of HIV transmission as well as allowing women self-protection against HIV infection. Here we evaluated the efficacy of vaginal application of the potent nonnucleoside reverse transcriptase inhibitor (NNRTI) MC 1220 against vaginal challenge of macaques with RT-SHIV, a chimeric simian immunodeficiency virus (SIV) containing the reverse transcriptase (RT) gene of HIV-1. Challenge infection of monkeys with RT-SHIV currently represents the only nonhuman primate model available to test the anti-HIV-1 effects of NNRTIs. Two different gel formulations containing different MC 1220 concentrations were evaluated for efficacy in female rhesus macaques exposed to RT-SHIV. Five groups of five animals each were treated with two different gel compositions containing no drug, 0.1% or 0.5% MC 1220, followed by vaginal RT-SHIV challenge 30 min later. One animal in each group treated with the low concentration of MC 1220 as well as one control animal remained uninfected after vaginal challenge. By contrast, three of the animals receiving 0.5% MC 1220 remained uninfected, suggesting a threshold of the drug. Despite being negative for plasma viral RNA and absence of seroconversion, almost all uninfected animals exhibited SIV-specific T cells, either in the periphery or in lymph nodes draining the portal of virus entry. Our results make MC 1220 a promising compound for further development as a topical microbicide and warrant additional testing with improved formulation, long-lasting vaginal delivery systems, or even combinations with other inhibitors.

Design of a semisolid vaginal microbicide gel by relating composition to properties and performance

PURPOSE

Develop a preclinical in vitro algorithm enabling de novo design of semisolid vaginal drug delivery gels, by using biomechanical modeling of gel spreading in the vaginal canal and empirically relating gel composition to mechanical properties and predicted performance.

METHODS

Gel performance was defined through a multivariate objective function constructed from gels' mechanical properties and selected performance criteria for gel spreading within the vaginal canal. Mixture design of experiment was used to establish a semi-empirical relationship linking composition-property and property-performance relationships for gels with varying concentrations of hydroxyethylcellulose and Carbopol 974P. This permits definition of a local optimum for gel composition and volume of administration, within a defined gel composition space.

RESULTS

Rheological behavior and, consequently, the value of the objective function varied broadly with composition. The algorithm indicated a 3.0 wt% HEC gel as the near optimal composition for a 3.5 mL applied volume for gels designed to spread throughout the vagina.

CONCLUSIONS

The algorithm introduced herein is a novel tool that facilitates an understanding of the composition-property-performance relationship for vaginal semisolid drug delivery gels. This approach has promise as a scientific methodology for evaluation and optimization of vaginal gels prior to in vivo investigations.

Complex hydrogel systems composed of polymers, liposomes, and cyclodextrins: implications of composition on rheological properties and aging

Rheological properties of complex hydrogels containing different amounts of liposomes and/or cyclodextrin (CD) were evaluated. Sonicated unilamellar vesicles (SUV) were loaded in a hydrogel composed of Carbopol 974 NF and hydroxyethylcellulose (Natrosol 250 HX). Phosphatidylcholine (PC) and hydrogenated-PC (HPC) liposomes, both mixed with cholesterol in a 2:1 lipid/chol mol ratio, were used. In some cases, hydroxypropyl-beta-cyclodextrin was also added (100 or 400 mg/mL). Gels were incubated at 40 degrees C/75% humidity for 7 days or 1 month to evaluate the effect of aging on their rheological properties. FTIR and DSC studies were performed to investigate possible interactions between the polymers and CD molecules at different CD concentrations. Static and dynamic rheological measurements were carried out. All gels had shear-thinning behavior (fitted well by the Cross model) with the exception of gels containing high concentrations of CD that were transformed into nonflowing elastic sticky solids, especially after aging. The more pronounced elastic behavior of gels containing 400 mg/mL CD is reflected by the higher values of relaxation strengths over all relaxation times. Complete interaction between polymers and CD, in the high-CD-content gels, as proven by FTIR and DSC studies, explains the dominating contribution of CD on gel characteristics. The addition of liposomes to such CD-containing gels has a substantial effect on their rheological properties, which are dependent on the liposome type (HPC/chol liposomes > PC/chol) and the lipid/CD ratio. This is explained by the "neutralization" of some CD molecules that prefer to interact with chol molecules that they extract from the lipid membranes. Gels with a high CD concentration (400 mg/mL) are almost insensitive to aging, whereas all other gels become slightly more elastic and less viscous as aging proceeds.

Liposomal drugs dispersed in hydrogels. Effect of liposome, drug and gel properties on drug release kinetics

Release of calcein and griseofulvin (GRF) from control (gels in which solutes are dissolved in) and liposomal gels was studied using agarose-assisted immobilization as a technique to separate gels from drug-receptor compartments. Liposomes composed of phosphatidylcholine (PC) or distearoyl-glycero-PC and cholesterol (DSPC/Chol), and incorporating calcein or GRF were prepared by thin film hydration. After cleaning the liposomes they were dispersed in different hydrogels (carbopol 974 [1, 1.5 or 2% (w/w)], hydroxylethyl-cellulose (HEC) [4% (w/w)], or a mixture of the two), and release of calcein or GRF was followed by fluorescence or photometric technique, respectively. Results show that calcein release from liposomal gels is slower compared to control gels, and can be further retarded by using rigid-membrane liposomes (faster release from PC-liposome compared to DSPC/Chol-liposome gels). Additionally, calcein release is not affected by the lipid amount loaded (in the range from 2 to 8 mg/ml), therefore solute loading can be controlled according to needs. Oppositely, GRF release from liposomal gels is determined by drug loading. At high drug loading levels (compared to GRF aqueous solubility), GRF is released with constant rate from liposomal gels irrespective of liposome type (PC or DSPC/Chol). Thereby, for amphiphilic/lipophilic drugs, drug properties (solubility, log P) determine the system behavior. Calcein and GRF release from control carbopol gels is faster compared to HEC and mixture gels. The same is true for calcein in liposomal gels. Carbopol gel rheological properties were found to be significantly different (compared to the other gels), implying that these characteristics are important for drug diffusion from gels.

Gels as vaginal drug delivery systems

The vagina has been used as a mucosal drug delivery route for a long time. Its single characteristics can be either limitative or advantageous when drug delivery is considered. Gels are semi-solid, three-dimensional, polymeric matrices comprising small amounts of solid, dispersed in relatively large amounts of liquid, yet possessing more solid-like character. These systems have been used and are receiving a great deal of interest as vaginal drug delivery systems. Gels are versatile and have been used as delivery systems for microbicides, contraceptives, labour inducers, and other substances. Although somewhat neglected in clinical studies, pharmaceutical characterization of vaginal gels is an important step in order to optimize safety, efficacy and acceptability. Indeed, the simple formulation of a gel can lead to different performances of systems containing the same amount of active substances. Therefore, this paper discusses and summarizes current use and research of vaginal drug delivery systems based in gels.

The physicodynamic properties of mucoadhesive polymeric films developed as female controlled drug delivery system

To develop an efficient female controlled drug delivery system (FcDDS) against sexually transmitted diseases (STDs), the polymeric films containing sodium dodecyl sulfate (SDS) were prepared with various compositions of Carbopol 934P, hydroxypropyl methylcellulose (HPMC) and polyethylene glycol (PEG). The physicochemical properties of mucoadhesive polymeric films, such as tensile strength, contact angle, swelling ratio and erosion rate in a vaginal fluid stimulant (VFS), were characterized. In addition, the drug release profile of SDS from the films and mucosal residence time were evaluated using a simulated dynamic vaginal system. It was demonstrated that the films made of Carbopol, HPMC and PEG were colorless, thin and soft and had proper physicodynamic properties for FcDDS. An increase in Carbopol content elevated tensile strength and swelling ratio but decreased the contact angle, erosion rate and the SDS release rate from the films. The films containing 0.25% (w/v) PEG as well as 0.75% (w/v) of combining Carbopol and HPMC remained on the vaginal tissue for up to 6h. The films containing the ratio of Carbopol:HPMC:PEG=1.5:1.5:1 and 1:2:1 seem to be optimal compositions for FcDDS, as they showed good peelability, relatively high swelling index and moderate tensile strength, and achieved the target release rate of SDS for 6h.

Effects of intrinsic variables on release of sodium dodecyl sulfate from a female controlled drug delivery system

The release profile of sodium dodecyl sulfate (SDS), a potent microbicide, from a female controlled drug delivery system (FcDDS) made of Carbopol 934P and hydroxypropyl methylcellulose (HPMC) was evaluated using a newly developed in vitro Simulant Vaginal System (SVS). The major parameters involved in the release profiles of SDS were categorized as: (1) formulation variables (total loading weight of intravaginal delivery systems, SDS loading doses in intravaginal delivery systems); (2) intrinsic variables (vaginal fluid secretion rate, vaginal fluid pH); and (3) extrinsic variables (inserting position). In most conditions, about 70% of the loading dose of SDS was released from FcDDS within 6h of application. The release profile showed that concentrations needed for complete human papilloma virus (HPV) inactivation could be obtained within 10 min after the application. It was demonstrated that intrinsic variables (i.e., the rate and pH of vaginal fluid) played an integral role in determining the release profile of SDS, while loading dose of SDS in FcDDS did not significantly affect the percentage of the total amount of SDS released. It can be concluded that FcDDS can be exploited as a controlled delivery device for prevention against sexually transmitted diseases.

Vaginal microbicides and teenagers

PURPOSE OF REVIEW

Sexually active teens are at significant risk from sexually transmitted infections and girls and women bear the greatest burden of these infections. New methods, such as vaginal microbicides, would provide female controlled options. Microbicides are currently in development and thus it is timely to discuss the progress made and factors that may influence acceptability for teens.

RECENT FINDINGS

Microbicide development presents many challenges, and several different potential mechanisms of action are being explored. There is interest in these products from women and men, and specific preferences are being investigated. Adolescents, due to reproductive system immaturity, developing cognitive abilities and the psychosocial context of their relationships, present a special set of challenges in efforts to foster microbicide use.

SUMMARY

Vaginal microbicides are on the horizon. Further study into teen issues is required to develop successful strategies for marketing and encouraging adolescent use of microbicides.

Biocompatibility of components of a female controlled drug delivery system

A female controlled drug delivery system (FcDDS) containing sodium dodecyl sulfate as a microbicide, ethylenediaminetetraacetic acid (EDTA) as a synergistic microbicide, and lactic acid as a pH modulator was developed as an intravaginal barrier device against sexually transmitted diseases. The host response of the vagina to the FcDDS was evaluated through biocompatibility tests including cell viability, estrogenicity, and cytotoxicity assays on HeLa cervical cells and NIH:Ovcar-3 ovarian cells. Gel electrophoresis and reverse transcriptase polymerase chain reaction assays on HeLa cervical cell lines were also performed to elucidate the effects of EDTA on the expression of particular proteins of interest. The results of the cell viability test showed no significant difference in viability of cells upon exposure to EDTA at concentrations less than 0.035% that was reported to exert spermicidal activity. EDTA at concentrations less than 0.035% did not cause any cytotoxicity. The results of reverse transcriptase polymerase chain reaction analysis revealed that EDTA induced the expression of a 67-kDa protein in HeLa cells, which was identified as elastin binding protein (a part of the elastin receptor complex). This work has demonstrated that FcDDS containing EDTA is biocompatible and safe to be used as an intravaginal barrier device.