Effects of chelating agents on the rheological property of cervical mucus

Effects of viscosity on sperm motility studied with optical tweezers

The purpose of this study is to analyze human sperm motility and energetics in media with different viscosities. Multiple experiments were performed to collect motility parameters using customized computer tracking software that measures the curvilinear velocity (VCL) and the minimum laser power (Pesc) necessary to hold an individual sperm in an optical trap. The Pesc was measured by using a 1064 nm Nd:YVO(4) continuous wave laser that optically traps motile sperm at a power of 450 mW in the focused trap spot. The VCL was measured frame by frame before trapping. In order to study sperm energetics under different viscous conditions sperm were labeled with the fluorescent dye DiOC(6)(3) to measure membrane potentials of mitochondria in the sperm midpiece. Fluorescence intensity was measured before and during trapping. The results demonstrate a decrease in VCL but an increase in Pesc with increasing viscosity. Fluorescent intensity is the same regardless of the viscosity level indicating no change in sperm energetics. The results suggest that, under the conditions tested, viscosity physically affects the mechanical properties of sperm motility rather than the chemical pathways associated with energetics.

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.

EDTA-induced activation of Ca-regulated proteins in the vaginal mucosa

The effects of EDTA on the expression and topologic localization of mitogen-activated protein (MAP) kinases (ERK, JNK, and p38), along with nitric oxide synthase (NOS), I-KappaB, and p53 were examined to elucidate the host response provoked by the intravaginal application of a female controlled drug delivery system (FcDDS) containing a spermicidal/microbicidal agent and EDTA. Immunohistochemical and immunoblotting studies were conducted to identify and quantitate the EDTA-inducible proteins in vaginal mucosa. The content of nitrite, which is one of the primary stable breakdown products of nitric oxide (NO), was determined to correlate the expression of NOS with NO formation in HeLa cervical carcinoma cell line. The immunohistochemical study demonstrated that the modulation of the calcium gradient by EDTA activated MAP kinases (ERK and JNK) in the rabbit vaginal mucosa. The results of Western immunoblot study demonstrated differential expression of MAP kinases (ERK and JNK) with EDTA treatment, whereas the expression of NOS and NF-KappaB was not affected by EDTA. There was no significant difference in nitrite production in the HeLa cell line upon exposure to EDTA compared with the control, which was consistent with the results of the Western blot study. The results of this work support that the regulation of MAP kinase was affected by calcium, which is controlled by chelation activity of EDTA. The specific tissue responses exerted by the loading components of a biomaterial-based system should be fully taken into consideration for its intravaginal application.

Characterization of a female controlled drug delivery system for microbicides

In this study, the feasibility of a carbopol 934P-HPMC-based gel formulation as a vaginal drug delivery system was evaluated. A vaginal fluid simulant (VFS) was utilized to simulate human vaginal mucus. The viscosity of the carbopol-HPMC gel system and VFS was examined using a cone and plate viscometer. The surface tension of VFS was measured using a capillary rising method. Differential scanning calorimetry (DSC) was employed to investigate the effect of carbopol gel on the conformational changes of rat vaginal membrane. The viscosity of carbopol gel increased as the pH of the system increased from 4.0 to 6.0. The viscosity of HPMC gel remained the same irrespective of pH of the system. The viscosity of the carbopol gel significantly increased, when HPMC (0.5-1.5%) was added to the system. The optimal viscosity value (1.5-2.0 poises) was achieved at 1.0-1.5% carbopol (pH 4.0) with the presence of 1.0-1.5% HPMC. There were mucin concentration dependent changes in viscosity and surface tension of VFS. The results of DSC analysis of rat vaginal membrane showed that the profiles of thermal stability for both carbopol-treated and the untreated control at the temperature ranging from 40 to 90 degrees C were almost identical. The thermal denaturation temperatures (Td) of the carbopol-treated membrane and the untreated control were not significantly different from each other. The combination of carbopol and HPMC seems to be an ideal formulation as a vaginal delivery system. Mucin played an important role in the regulation of viscosity and surface tension of VFS. DSC study demonstrated that carbopol gel showed good biocompatibility and did not cause any conformational changes in rat vaginal membrane.