Toxicology of polymers for implant contraceptives for women

FD-2, an Anticervical Stenosis Device for Patients Undergoing Radical Trachelectomy or Cervical Conization

This study aimed to introduce FD-2, a newly developed anticervical stenosis device for patients with cervical cancer undergoing radical trachelectomy. Using ethylene-vinyl acetate copolymers, we developed FD-2 to prevent uterine cervical stenosis after radical trachelectomy. The tensile test and extractables and leachables testing were performed to evaluate FD-2's safety as a medical device. FD-2 was indwelled in three patients with cervical cancer during radical trachelectomy and its utility was preliminarily evaluated. FD-2 consists of a head (fish-born-like structure), neck (connecting bridges), and body (tubular structure); the head is identical to FD-1, an intrauterine contraceptive device. FD-2 passed the tensile test and extractables and leachables testing. The average time required for the application or removal of FD-2 in cervical cancer patients was less than 10 s. The median duration of FD-2 indwelling was 8 weeks. No complications, including abdominal pain, pelvic infections, or hemorrhages, associated with FD-2 indwelling were reported. At the 3-12-month follow-up after the radical trachelectomy, no patients developed cervical stenosis or experienced dysmenorrhea. In conclusion, we developed FD-2, a novel device that can be used for preventing cervical stenosis after radical trachelectomy for uterine cervical cancer.

Understanding Breast Implant Illness: Etiology is the Key

Because breast augmentation is one of the most popular cosmetic procedures, the issue of implant-related complications has been widely debated ever since the FDA approved the use of implants in 1962. Although decades have passed, breast implant illness (BII) still represents a poorly defined and controversial complication. With ongoing nonscientific discussion in the mainstream media and on social media, revealing the etiology of BII is urgent because knowledge of this subject ultimately influences patients' decisions. Little or no scientific research is currently available on BII and no final conclusions regarding its etiology, clinical manifestations, diagnostic criteria, or treatment have been made. This review aims to give an overview of the hypotheses on the etiology of BII and seeks inspiration to improve the conditions of BII patients.

Development of Hormonal Intravaginal Rings: Technology and Challenges

Intravaginal rings (IVRs) are minimally invasive polymeric devices specifically designed to be used for the sustained and prolonged release of various type of drugs such as hormones. One of the benefits of using topical drug delivery systems (e.g., IVRs) is the fact that systemic drug delivery may cause drug resistance due to elevated drug levels. Topical drug delivery also provides higher concentrations of the drug to the target site and has fewer side effects. In addition, when a drug is administered vaginally, the hepatic first-pass effect is avoided, resulting in higher absorption. Contraception and treatments for specific diseases such as endometriosis and hormone deficiencies can be improved by the administration of hormones via an IVR. This article aims to classify and compare various designs of commercially available and non-commercial hormonal IVRs and to analyze their performance. Current challenges affecting the development of IVRs are investigated, and proposed solutions are discussed. A comprehensive search of publications in MEDLINE/PubMed and of commercial product data of IVRs was performed, and the materials, designs, performance, and applications (e.g., contraception, endometriosis, estrogen deficiency and urogenital atrophy) of hormonal IVRs were thoroughly evaluated. Most hormonal IVRs administer female sex hormones, i.e., estrogen and progestogens. In terms of material, IVRs are divided into 3 main groups: silicone, polyurethane, and polyethylene-co-vinyl acetate IVRs. As regards their design, there are 4 major designs for IVRs which strongly affect their performance and the timing and rate of hormone release. Important challenges include reducing the burst release and maintaining the bioavailability of hormones at their site of action over a prolonged period of administration as well as lowering production costs. Hormonal IVRs are a promising method which could be used to facilitate combination therapies by administering multiple drugs in a single IVR while eliminating the side effects of conventional drug administration methods. IVRs could considerably improve womenʼs quality of life all over the world within a short period of time.

Biomaterials and Contraception: Promises and Pitfalls

The present state of reproductive and sexual health around the world reveals disparities in contraceptive use and effectiveness. Unintended pregnancy and sexually transmitted infection transmission rates remain high even with current prevention methods. The 20th century saw a contraceptive revolution with biomedical innovation driving the success of new contraceptive technologies with central design concepts and materials. Current modalities can be broadly categorized according to their mode of function: reversible methods such as physical/chemical barriers or hormonal delivery devices via systemic (transdermal and subcutaneous) or localized (intrauterine and intravaginal) administration, and nonreversible sterilization procedures such as tubal ligation and vasectomy. Contraceptive biomaterials are at present dominated by well-characterized elastomers such as polydimethylsiloxane and ethylene vinyl acetate due to their favorable material properties and versatility. Contraceptives alter the normal function of cellular components in the reproductive systems to impair fertility. The purpose of this review is to highlight the bioengineering design of existing methods, explore novel adaptations, and address notable shortcomings in current contraceptive technologies.

Surface roughness of different contraceptive vaginal rings: evaluation by scanning electron microscope (SEM)

Objective: The aim of the study was to evaluate whether the compositions of the ethylene vinyl acetate (EVA) membrane of two different contraceptive vaginal rings could influence the surface roughness, which is associated with the possible accumulation of vaginal biomass on the rings during use.Methods: We measured and compared the surface roughness of unused vaginal rings, NuvaRing and Ornibel, using a scanning electron microscope (SEM) and dedicated software that can convert SEM images into 3D models. Average roughness (Ra), average quadratic roughness (Rq) and mean height of the irregularities at 10 points (Rz) were calculated.Results: Different thicknesses of the EVA membranes between the two rings were noted. No significant differences were found between the two rings in the three evaluated values of surface roughness (NuvaRing vs Ornibel, respectively: Ra, 1.53 ± 0.14 vs 1.61 ± 0.14 µm, p = 0.141; Rq, 2.03 ± 0.25 vs 2.07 ± 0.16 µm, p = 0.688; Rz, 11.4 ± 3.1 vs 11.4 ± 2.4 µm, p = 0.987).Conclusion: The different composition of the vaginal rings' EVA membrane is not associated with different surface roughness. Ornibel is equivalent to NuvaRing in terms of surface roughness, despite the different composition of the membrane polymers.

Fabrication, Characterization, and Properties of Poly (Ethylene-Co-Vinyl Acetate) Composite Thin Films Doped with Piezoelectric Nanofillers

Ethylene vinyl acetate (EVA) is a copolymer comprehending the semi-crystalline polyethylene and amorphous vinyl acetate phases, which potentially allow the fabrication of tunable materials. This paper aims at describing the fabrication and characterization of nanocomposite thin films made of polyethylene vinyl acetate, at different polymer concentration and vinyl acetate content, doped with piezoelectric nanomaterials, namely zinc oxide and barium titanate. These membranes are prepared by solvent casting, achieving a thickness in the order of 100-200 µm. The nanocomposites are characterized in terms of morphological, mechanical, and chemical properties. Analysis of the nanocomposites shows the nanofillers to be homogeneously dispersed in EVA matrix at different vinyl acetate content. Their influence is also noted in the mechanical behavior of thin films, which elastic modulus ranged from about 2 to 25 MPa, while keeping an elongation break from 600% to 1500% and tensile strength from 2 up to 13 MPa. At the same time, doped nanocomposite materials increase their crystallinity degree than the bare ones. The radiopacity provided by the addition of the dopant agents is proven. Finally, the direct piezoelectricity of nanocomposites membranes is demonstrated, showing higher voltage outputs (up to 2.5 V) for stiffer doped matrices. These results show the potentialities provided by the addition of piezoelectric nanomaterials towards mechanical reinforcement of EVA-based matrices while introducing radiopaque properties and responsiveness to mechanical stimuli.

Oxidatively Stable Polyolefin Thermoplastics and Elastomers for Biomedical Applications

Statistical copolymers were prepared by the Ring Opening Metathesis coPolymerization (ROMP) of (Z)-5,5-dimethylcyclooct-1-ene and cis-cyclooctene. Subsequent hydrogenation yielded poly(ethylene-co-isobutylene) (PEIB) materials. The feed ratio of the comonomers controls the degree of branching and resulting thermal and mechanical properties of the PEIB samples. Oxidative degradation studies, conducted under accelerated in vitro conditions were used to assess and predict their long-term biostability. Relative to commercial poly(ether urethanes) and a structurally similar polyolefin, poly(ethylene-co-1-butylene), the PEIB samples showed much better oxidative resistance. The facile synthesis, improved stability, and excellent mechanical performance of these PEIB materials bode well for their use in biomedical applications that require long-term biostability.

A comparative study of Shilajatu and Asanadi Ghana Vati in the management of Madhumeha w.s.r. to type-2 diabetes mellitus

Introduction:

Diabetes mellitus is becoming an alarming problem for society nowadays causing impediment in normal life. Diabetes and its complications impose a major burden upon health-care facilities.

Materials and Methods:

In this study, 90 patients of Madhumeha (type-2 diabetes mellitus) were registered and randomly divided into two groups. Out of 90 registered patients, 80 patients completed the treatment. In Group A, cap. Shilajatu (500 mg twice daily) was given for 3 months and in Group B, Asanadi Ghana Vati (2 Vati twice daily) was given for 3 months.

Aim:

An attempt was made to evaluate and compare the efficacy of Shilajatu and Asanadi Ghana Vati in the management of type-2 diabetes mellitus. The efficacy of therapy was assessed on the basis of improvement in sign and symptoms of diabetes mellitus, blood sugar level, and glycosylated hemoglobin

Results:

Statistically significant improvement was observed in sign and symptoms as well as on blood sugar level in both groups after the completion of treatment.

Conclusion:

Shilajatu and Asanadi Ghana Vati seem to be effective and completely safe for the management of Madhumeha (type-2 diabetes mellitus).

Vaginal health in contraceptive vaginal ring users - A review

BACKGROUND

To provide an overview of the available data from clinical studies of vaginal conditions in women who use a vaginal ring as a contraceptive.

METHODS

A systematic review of the literature.

RESULTS

Millions of women have already used the ethylene vinyl acetate vaginal ring that releases ethinylestradiol and etonogestrel for contraception. Because of its small size, more than four out of five women using the ring report that they do not feel it, even during sexual intercourse. No colposcopic or cytological changes have been observed in users, although approximately 10% have increased vaginal discharge. While in vitro studies have shown adhesion of Candida yeasts to the vaginal ring surface, clinical studies have not demonstrated a greater incidence of Candida infections compared to users of equivalent oral contraceptives. Some clinical studies suggest a lower incidence of bacterial vaginosis. No interaction exists between concomitant use of the vaginal ring and other drugs or products for vaginal use.

CONCLUSION

The use of a contraceptive vaginal ring does not alter the vaginal ecosystem and therefore does not substantially affect vaginal health.

Controlled-release vaginal ring drug-delivery systems: a key strategy for the development of effective HIV microbicides

BACKGROUND

Over half of all HIV-infected adults are women and heterosexual intercourse is a significant mode of viral transmission. This review examines the potential for using polymeric vaginal ring systems to provide controlled delivery of HIV microbicides in order to prevent heterosexual transmission of the virus.

DISCUSSION

Continuous delivery of microbicides has the potential to be more effective than one-off dosing. Thus, controlled-release vaginal delivery devices are now a key area of HIV prevention research. Initial clinical trials on vaginal rings loaded with dapivirine (a candidate microbicide) have indicated that these products are safe and well tolerated by women. These devices are female-initiated, robust and capable of long-term delivery of the active agent.

CONCLUSIONS

Vaginal rings may offer an effective system for the controlled delivery of microbicides to prevent heterosexual transmission of HIV. Candidate vaginal ring microbicide products are now in clinical trials.

In vivo biocompatibility of three potential intraperitoneal implants

The intraperitoneal biocompatibility of PDMS, polyHEMA and pEVA was investigated in rats, rabbits and rhesus monkeys. No inflammation was evidenced by hematological analyses and measurement of inflammatory markers throughout the experiment and by post-mortem examination of the pelvic cavity. After 3 or 6 months, histological analysis revealed fibrous tissue encapsulating PDMS and PEVA implants in all species and polyHEMA implants in rabbits and monkeys. Calcium deposits were observed inside polyHEMA implants. The intraperitoneal biocompatibility of all 3 polymers makes them suitable for the design of drug delivery systems, which may be of great interest for pathologies confined to the pelvic cavity.

Controlled release of 5-fluorouridine from radiation-crosslinked poly(ethylene-co-vinyl acetate) films

The effect of gamma-radiation doses of 12.5-380 kGy on the infrared spectra, gel content, mechanical properties, and the release of oxobutyl-5-fluoro-2'-deoxyuridine (OfdUrd, an antitumor agent) from poly(ethylene-co-vinyl acetate) (EVA) films was studied. The results showed that the application of radiation doses produced a crosslinking reaction leading to a maximum gel content of about 85% in the case of 150 kGy. Higher doses did not increase the gel content in EVA films. The mechanical properties (tensile strength, percentage elongation at break and Young's modulus) of all studied EVA matrices were affected by the exposure to gamma-radiation. Irradiation doses over 50 kGy caused an increase in the Young's modulus of EVA and at the same time a decrease in the strain per cent. Moreover, the network structure formed after irradiation reduced significantly the OFdUrd release from EVA films. In this manner, the radiation dose applied to the polymeric matrix modulated the release of OFdUrd, avoiding the high concentrations that may cause severe systemic toxicity. The loading of OFdUrd to EVA film triggered a slight hyperemia after implantation, while the inflammatory reaction was only observed during the first two days.

A scanning electron microscopic study of the contraceptive vaginal ring

OBJECTIVE

To compare by electron microscopy the surface of vaginal contraceptive rings before and after use.

METHODS

A single ring was worn for 28 days by a volunteer with normal vaginal flora. This worn ring was then cut in half, with one half placed directly into fixative and the other half rinsed to remove visible mucus prior to being placed into the fixative. Another ring was taken directly from the package and placed in fixative. The surfaces of the three ring samples were studied by scanning electron microscopy at varying magnifications to ascertain if there was penetration of bacteria into the vinyl polymer or if the ring surface was altered with 1 month of use.

RESULTS

The ring half placed directly into fixative with visible mucus had cellular debris on its surface but no evidence of material penetration. The other half of the ring worn for 28 days and rinsed before fixation had a similar surface appearance to the unused ring.

CONCLUSIONS

The surface of the ethylene vinyl acetate contraceptive vaginal ring is remarkably uniform and after 1 month of use was without visible evidence of erosion, embedded bacteria or structural changes compared to an unused ring.

Development of a long-acting therapeutic system: Part I: A method to produce silicon rubbers with well-defined microstructures

Based on the free-volume theory of diffusion in rubbers it is shown that the diffusion coefficient D of a permeating drug can be written as the product of two probabilities D approximately w(1)w(2). The polymer chains in a rubber are subject to thermal vibrations. Hence collisions between vibrating polymer segments and permeating drug molecules can occur. w(1) describes the probability that by such a collision a drug molecule experiences an energy exchange which is large enough to overcome its interactions with its neighborhood. w(2) describes the probability that a permeating drug molecule will find in its immediate neighborhood a free volume being equal or larger than its own volume. Diffusion takes place if the drug molecule experiences a sufficiently large exchange of momentum and finds at the same time a sufficiently large free volume. As both events are independent their overall probability is given by the product of the two probabilities. For a given rubber and a given species of drug molecules in a first approximation w(1) can be considered as constant. This means the diffusion coefficient is mainly determined by w(2). This probability, however, is strongly determined by the microstructure of the rubber. In this study a procedure is developed allowing for a straightforward synthesis of silicone rubbers with defined network density.

Biocompatibility of implantable synthetic polymeric drug carriers: focus on brain biocompatibility

Numerous polymeric biomaterials are implanted each year in human bodies. Among them, drug delivery devices are potent novel powerful therapeutics for diseases which lack efficient treatments. Controlled release systems are in direct and sustained contact with the tissues, and some of them degrade in situ. Thus, both the material itself and its degradation products must be devoid of toxicity. The knowledge and understanding of the criteria and mechanisms determining the biocompatibility of biomaterials are therefore of great importance. The classical tissue response to a foreign material leads to the encapsulation of the implant, which may impair the drug diffusion in the surrounding tissue and/or cause implant failure. This tissue response depends on different factors, especially on the implantation site. Indeed, several organs possess a particular immunological status, which may reduce the inflammatory and immune reactions. Among them, the central nervous system is of particular interest, since many pathologies still need curative treatments. This review describes the classical foreign body reaction and exposes the particularities of the central nervous system response. The recent in vivo biocompatibility studies of implanted synthetic polymeric drug carriers are summarized in order to illustrate the behavior of different classes of polymers and the methodologies used to evaluate their tolerance.

Pathogenetic and diagnostic aspects of siliconosis

Silicones have an adverse effect on human health well beyond that suggested by the recent superficial public controversy. The evidence for immune responses to injected/implanted silicones is extensive, detailed, often very specific, and not at all new. Comprehending the immunopathogenicity, realized and potential, of silicone has grown as our general understanding of the immune system has developed. Several major issues in furthering this comprehension pertain to the nature of the essential epitope, special risk of silicones to women, and definition of the chronic disease complex so evident clinically, one defying classification within currently traditional disease categories and states. The commentary presented here emphasizes the immunopathic evidence, explores the question of the essential epitope, estimates the minimal threshold of silicone load for immune reactivity, presents a profile of autoantibodies for siliconosis, and calls attention to specific silicone-based female contraceptive modalities. The silicone content of personal care products, not always revealed by retail package labeling, is explored as a potential sensitizing factor in the environment.

Safety of implantable contraceptives for women: data from observational studies

Contraceptive implants are registered in over 60 countries and have been used by millions of women for three decades. This article reviews findings from observational studies on the safety of contraceptive implants and examines the risk of specific health outcomes. Fifty-five articles were reviewed, and the body of evidence for each health outcome was summarized. Available evidence suggests that contraceptive implants are safe and, overall, implant users do not experience adverse events at rates higher than women not using implants. With respect to specific outcomes, the evidence suggests no increased risks of pelvic inflammatory disease, decreased bone mineral density, anemia, thrombocytopenia, or death with implant use. The evidence was too limited to draw meaningful conclusions for neoplastic disease, cardiovascular events, and HIV/AIDS. Nonsignificantly elevated associations were reported for diabetes, serious mental disorders, and rheumatoid arthritis. Conditions for which risks were marginally, yet significantly, elevated were hypertension and gall bladder disease.