Efficacy and Safety of a New Vaginal Contraceptive Antimicrobial Formulation Containing High Molecular Weight Poly(Sodium 4-Styrenesulfonate)

BIOLOGY OF REPRODUCTION 66, 886–894 (2002) Efficacy and Safety of a New Vaginal Contraceptive Antimicrobial Formulation Containing High Molecular Weight Poly(Sodium 4-Styrenesulfonate)1 Lourens J.D. Zaneveld,2,3 Donald P. Waller,4 Robert A. Anderson,3 Calvin Chany II,3 William F. Rencher,5 Kenneth Feathergill,3 Xiao-Hui Diao,3 Gustavo F. Doncel,5 Betsy Herold,6 and Morris Cooper7 ABSTRACT INTRODUCTION Host cell infection by sexually transmitted disease (STD)causing microbes and fertilization by spermatozoa may have some mechanisms in common. If so, certain noncytotoxic agents could inhibit the functional activity of both organisms. High molecular mass poly(sodium 4-styrenesulfonate) (T-PSS) may be one of these compounds. T-PSS alone (1 mg/ml) or in a gel (2% or 5% T-PSS) completely prevented conception in the rabbit. Contraception was not due to sperm cytotoxicity or to an effect on sperm migration. However, T-PSS inhibited sperm hyaluronidase (IC50 5 5.3 mg/ml) and acrosin (IC50 5 0.3 mg/ml) and caused the loss of acrosomes from spermatozoa (85% maximal loss by 0.5 mg/ml). T-PSS (5% in gel) also reduced sperm penetration into bovine cervical mucus (73% inhibition by 1 mg gel/ml). T-PSS (5% in gel) inhibited human immunodeficiency virus (HIV; IC505 16 mg gel/ml) and herpes simplex viruses (HSV-1 and HSV-2; IC50 5 1.3 and 1.0 mg gel/ml, respectively). The drug showed high efficacy against a number of clinical isolates and laboratory strains. T-PSS (5% in gel) also inhibited Neisseria gonorrhea (IC50 , 1.0 gel/ml) and Chlamydia trachomatis (IC50 5 1.2 mg gel/ml) but had no effect on lactobacilli. These results imply that T-PSS is an effective functional inhibitor of both spermatozoa and certain STD-causing microbes. The noncytotoxic nature should make T-PSS safe for vaginal use. T-PSS was nonmutagenic in vitro and possessed an acute oral toxicity of .5 g/kg (rat). Gel with 10% T-PSS did not irritate the skin or penile mucosa (rabbit) and caused no dermal sensitization (guinea pig). Vaginal administration of the 5% T-PSS gel to the rabbit for 14 consecutive days caused no systemic toxicity and only mild (acceptable) vaginal irritation. T-PSS in gel form is worthy of clinical evaluation as a vaginal contraceptive HIV/ STD preventative. Acquired immunodeficiency syndrome (AIDS) has caused a worldwide crisis. An estimated 5.8 million new infections by the human immunodeficiency virus (HIV) occurred in 1998, approximately 16 000 each day [1]. By the end of 1998, more than 43 million people had AIDS or were infected with the HIV virus. Presently, the majority of HIV infections occur through heterosexual contact. Women are particularly at risk. In 1998, 43% of the AIDS cases or HIV infections were in women [1]. Prevalences of other sexually transmitted diseases (STDs) are also on the rise. In 1995, more than 333 million new cases of Chlamydia and Trichomonas infections, gonorrhea, and syphilis occurred worldwide [2]. Not only are these other STDs a serious problem by themselves but they also increase the risk of HIV infection [3]. At the same time, the world population continues its steep rise [4]. The tragedy, suffering, and costs associated with infectious diseases and overpopulation are staggering. For women, only those techniques preventing contact of semen with the genital tract or methods that inactivate HIV and STD pathogens and spermatozoa after ejaculation can prevent both infection and unplanned pregnancies. Condoms, both male and female, provide a physical barrier to the seminal contents, but because the use of these devices has been limited they have not had a major impact on disease prevention. In many cultures, it is difficult for woman to negotiate condom use. Thus, it is important to develop woman-controlled methodologies, i.e., prophylactic vaginal products, such as gels, suppositories, and foams, that are microbicidal and spermicidal. Vaginal contraceptive products have been available for many years and usually contain the membrane-cytotoxic detergent/surfactant nonoxynol-9 as the active ingredient [5, 6]. However, frequent use of nonoxynol-9 products can cause irritation and inflammation of the vagina [7–9]. Nonoxynol-9 is toxic to vaginal and cervical cells [10], increases the permeability of vaginal tissue [11], and can inactivate lactobacilli [12, 13]. Lactobacilli produce lactic acid and hydrogen peroxide that serve to maintain the acidic pH of the vagina (approximately 3.5–5.0). At this pH, a number of STD-causing organisms, HIV, and spermatozoa are inactivated [14–16]. Disturbance of the vaginal microbial milieu can lead to vaginal infections, which in turn increase the chance of HIV/STD transmission [17]. Vaginal contraceptive products that contain nonoxynol9 have high efficacy in preventing vaginal but not rectal fertilization, sperm, sperm motility and transport, toxicology, vagina Support for this project was provided by the CICCR Program of the Contraceptive Research and Development Program, Eastern Virginia Medical School (contracts CIG-96-01 and CIG-00-48), the Rockefeller Foundation (grant RF95021), and the National Institute for Allergy and Infectious Diseases (grant PO1 A137940). The views expressed by the authors do not necessarily reflect the views of the funding agencies. 2 Correspondence: L. Zaneveld, Section of Ob/Gyn Research, Rush-Presbyterian-St. Luke’s Medical Center, 1653 West Congress Parkway, Chicago, IL 60612. FAX: 312 942 2771; e-mail: 1 Received: 16 April 2001. First decision: 19 May 2001. Accepted: 31 October 2001. Q 2002 by the Society for the Study of Reproduction, Inc. ISSN: 0006-3363. http://www.biolreprod.org 886 Program for the Topical Prevention of Conception and Disease,3 Department of Obstetrics and Gynecology, Rush University, Rush-Presbyterian-St. Luke’s Medical Center, Chicago, Illinois 60612 Program for the Topical Prevention of Conception and Disease,4 Department of Pharmaceutics and Pharmacodynamics, University of Illinois at Chicago, Chicago, Illinois 60612 Contraceptive Research and Development Program,5 Eastern Virginia Medical School, Norfolk, Virginia 23507 Department of Pediatric Infectious Diseases,6 Mount Sinai Medical Center, New York, New York 10029 Department of Medical Microbiology and Immunology,7 Southern Illinois University, Springfield, Illinois 62794 CONTRACEPTIVE ANTIMICROBIAL FORMULATION utilizing a water-based polymerization of 4-styrenesulfonate that eliminates toxic residues in the preparation. This product is referred to as T-PSS. Initial tests with T-PSS showed inhibition of herpes simplex viruses (HSV-1 and HSV-2), Neisseria gonorrhea, and Chlamydia trachomatis [41]. These preliminary results encouraged the further evaluation of T-PSS for its sperm inhibitory, contraceptive, and antimicrobial properties. Studies focused on the compound in gel because this is the method whereby T-PSS will be used vaginally, but information was also obtained on the compound alone (drug subst (...truncated)