In vitro test to evaluate the interaction between synthetic cervical mucus and vaginal formulations

Biopolymeric Mucin and Synthetic Polymer Analogs: Their Structure, Function and Role in Biomedical Applications

Mucin networks are viscoelastic fibrillar aggregates formed through the complex self-association of biopolymeric glycoprotein chains. The networks form a lubricious, hydrated protective shield along epithelial regions within the human body. The critical role played by mucin networks in impacting the transport properties of biofunctional molecules (e.g., biogenic molecules, probes, nanoparticles), and its effect on bioavailability are well described in the literature. An alternate perspective is provided in this paper, presenting mucin’s complex network structure, and its interdependent functional characteristics in human physiology. We highlight the recent advances that were achieved through the use of mucin in diverse areas of bioengineering applications (e.g., drug delivery, biomedical devices and tissue engineering). Mucin network formation is a highly complex process, driven by wide variety of molecular interactions, and the network possess structural and chemical variations, posing a great challenge to understand mucin’s bulk behavior. Through this review, the prospective potential of polymer based analogs to serve as mucin mimic is suggested. These analog systems, apart from functioning as an artificial model, reducing the current dependency on animal models, can aid in furthering our fundamental understanding of such complex structures.

Feasibility of radiolabeled small molecule permeability as a quantitative measure of microbicide candidate toxicity

OBJECTIVE

To determine the feasibility of using quantitative changes in vaginal permeability to small molecules as a measure of candidate microbicide toxicity.

STUDY DESIGN

Controlled, open-labeled, prospective study. Seven healthy women received a single vaginal dose of hydroxyethylcellulose gel (HEC), nonoxynol-9 (N-9) or K-Y Jelly. Each gel was radiolabeled with a small molecule ((99m)Tc-DTPA) followed by 12-h blood and urine collection. Pharmacokinetic (PK) parameters of (99m)Tc-DTPA were calculated to compare the impact of each gel on vaginal permeability. Each woman served as her own control. The Friedman test with post hoc Wilcoxon test was used to detect differences among the gels.

RESULTS

Vaginal permeability of (99m)Tc-DTPA was highest for the N-9 radiolabel. N-9 plasma area under the concentration curve was 2.7-fold higher (p=.04), and peak concentration was threefold higher (p=.04) compared to HEC. There were no significant PK parameter differences between HEC and K-Y Jelly or between N-9 and K-Y Jelly. Cumulative dose-adjusted median (interquartile range) 12-h timed urine gamma activity was 66.70 × 10(-4)μCi (27.90-152.00) following HEC dosing, 103.00 × 10(-4)μCi (98.20-684.00) following N-9 gel dosing and 20.30 × 10(-4)μCi (11.10-55.90) following K-Y gel dosing. The differences between urine HEC and K-Y Jelly (p=.047) and between N-9 and K-Y Jelly (p=.016) were statistically significant.

CONCLUSIONS

It is feasible to measure differences in vaginal permeability among vaginal gels using a radiolabeled small molecule, though there are permeability differences that require a nuanced understanding of gel composition to interpret the results.

IMPLICATIONS

Establishing the safety of both vehicle and active pharmaceutical ingredient is an essential task in microbicide development, to be determined as soon as possible. This study suggests that a combination of microbicide toxicity assessments, that is, cervicovaginal permeability, inspection and histopathology, may need to be studied simultaneously.

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.