Synthesis, characterization and preclinical formulation of a dual-action phenyl phosphate derivative of bromo-methoxy zidovudine (compound WHI-07) with potent anti-HIV and spermicidal activities

Biocompatible polyvinyl alcohol and RISUG® blend polymeric films with spermicidal potential

Majority of the commercially available vaginal contraceptives encompasses cervicovaginal membrane disrupting detergent molecules as pharmacologically active ingredients. Development of a tissue-compatible vaginal contraceptive agent is necessary to circumvent the existing demand for female contraception in the reproductive healthcare sector. With this objective, the present study delineates the use of RISUG^® based non-hormonal female contraceptive films. RISUG^® was blended with polyvinyl alcohol (PVOH) to formulate biodegradable intra-vaginal contraceptive films. The formulated films were characterized for their thermal, physiochemical and biological features. The results showed that both RISUG^® and PVOH were miscible and interacted at the intermolecular level. Variations in the concentration of RISUG^® resulted in the changes in physicochemical, thermal and rheological characteristics of the formulated blends. In vitro toxicological assay of the polymeric formulations did not show any significant toxicity. However, the blend films retained spermicidal potential of RISUG^®. Furthermore, in vivo toxicological evaluation of the polymeric blend in the rat model revealed about their biocompatibility with no significant organ toxicity, hematological and biochemical alterations. These results together confirm the potential applicability of the PVOH:RISUG^® blend films as a vaginal contraceptive.

Mucosal Toxicity Studies of a Gel Formulation of Native Pokeweed Antiviral Protein

Pokeweed antiviral protein (PAP), a 29-kDa plant-derived protein isolated from Phytolacca americana, is a promising nonspermicidal broad-spectrum antiviral microbicide. This study evaluated the mucosal toxicity potential of native PAP in the in vivo rabbit vaginal irritation model as well as the in vitro reconstituted human vaginal epithelial tissue model. Twenty-two New Zealand white rabbits in 4 subgroups were exposed intravaginally to a gel with and without 0.01, 0.1, or 1.0% native PAP for 10 consecutive days. The dose of PAP used represented nearly 200- to 20,000 times its in vitro anti-HIV IC50 value. Animals were euthanized on day 11 and vaginal tissues were evaluated for histologic and immunohistochemical evidence of mucosal toxicity, cellular inflammation, and hyperplasia. Blood was analyzed for changes in hematology and clinical chemistry profiles. Reconstituted human vaginal epithelial tissue grown on membrane filters was exposed to 0.1, 0.1, or 1.0% native PAP in medium or topically via a gel for 24 hours and tissue damage was evaluated by histological assessment. In the in vivo rabbit vaginal irritation model, half of all PAP-treated rabbits (8/16) exhibited an acceptable range of vaginal mucosal irritation (total score <8 out of a possible 16), whereas nearly a third of PAP-treated rabbits (5/16) developed moderate to marked vaginal mucosal irritation (total score >11). However, no treatment-related adverse effects were seen in hematological or clinical chemistry measurements. Furthermore, in vitro exposure of a 3-dimensional human vaginal tissue grown on polycarbonate membrane filters to identical concentrations of PAP either added to culture medium or applied topically via gel formulation did not result in direct toxicity as determined by histologic evaluation. These findings indicate careful monitoring of vaginal irritation will be required in the clinical development of PAP as a nonspermicidal microbicide.

Spermicidal and contraceptive potential of desgalactotigonin: a prospective alternative of nonoxynol-9

Crude decoction of Chenopodium album seed showed spermicidal effect at MIC 2 mg/ml in earlier studies. Systematic isolation, characterization and evaluation revealed that the major metabolite Desgalactotigonin (DGT) is the most effective principle in both in vitro and in vivo studies. The in vitro studies comprises (a) rat and human sperm motility and immobilizing activity by Sander-Cramer assay; (b) sperm membrane integrity was observed by HOS test and electron microscopy; (c) microbial potential was examined in Lactobacillus broth culture, and (d) the hemolytic index was determined by using rat RBCs. The in vivo contraceptive efficacy was evaluated by intra uterine application of DGT in rat. Lipid peroxidation and induction of apoptosis by DGT on human spermatozoa were also studied. The minimum effective concentration (MEC) of DGT that induced instantaneous immobilization in vitro was 24.18 µM for rat and 58.03 µM for human spermatozoa. Microbial study indicated DGT to be friendly to Lactobacillus acidophilus. Implantation was prevented in DGT treated uterine horn while no hindrance occurred in the untreated contra lateral side. At the level of EC₅₀, DGT induced apoptosis in human spermatozoa as determined by increased labeling with Annexin-V and decreased polarization of sperm mitochondria. Desgalactotigonin emerged 80 and 2×10⁴ times more potent than the decoction and Nonoxynol-9 respectively. It possesses mechanism based detrimental action on both human and rat spermatozoa and spares lactobacilli and HeLa cells at MEC which proves its potential as a superior ingredient for the formulation of a contraceptive safer/compatible to vaginal microflora.

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.

Evaluation of safety margins of Chenopodium album seed decoction: 14-day subacute toxicity and microbicidal activity studies

BACKGROUND

Sperm immobilizing activity and plausible mechanism of action of Chenopodium album seed decoction (CAD) have been elucidated in our earlier studies. The present study has been carried out to explore the safety standards of CAD along with microbicidal properties as prerequisite for its use as a topically applicable vaginal contraceptive.

METHODS

The safety standards of CAD were assessed by a) Hemolytic index determination using rabbit erythrocytes, to set the doses of the other experiments, b) Dermal irritancy test using refined version of Draize scoring system on rabbits, c) Possible effect on local tissues and reproductive performance in female rats after fourteen daily single dose application, d) PCNA staining- to evaluate the effect of CAD on vaginal tissue proliferation, e) TUNEL assay- to examine its ability to induce in situ apoptosis in the vaginal tissue sections of the treated animals, and f) Microbicidal activity- to explore the effect of CAD on the growth of Lactobacillus acidophilus and Candida albicans.

RESULTS

In vitro irritation studies on rabbit erythrocytes revealed the hemolytic index of CAD to be 8.2 mg/ml. The dermal irritation test showed it to be a non-irritant even at higher doses. Intra vaginal application of CAD in rat vagina for 14 consecutive days caused slight reversible inflammation on vaginal epithelial cells at doses as high as 82 mg/ml. However, at this dose level it neither had any adverse effect on vaginal tissue proliferation nor did it cause in situ apoptosis as evident from PCNA staining and TUNEL assay. Fertility and fecundity were restored 4-15 days after withdrawal of CAD application. At dose level 10 times that of its spermicidal MEC (minimum effective concentration), CAD did not block the growth of Lactobacillus, although the size of individual colony was marginally reduced. However, growth of the pathogenic fungus Candida albicans was completely inhibited with 20 mg/ml of CAD.

CONCLUSION

The overall result evolved from the study strengthens the candidature of CAD as a safe microbicidal spermicide. It is almost non-irritant to rabbit skin and rat vaginal tissues at doses 10 fold higher than its hemolytic index. The effect of CAD on Lactobacillus culture was not highly encouraging but it prevented the growth of the fungal pathogen Candida albicans at 20 mg/ml of CAD.

Microbicidal spermicide or spermicidal microbicide?

Vaginal contraception, the oldest method of fertility regulation that remained virtually forgotten for a few decades has recently come under focal review due to an increase in STDs and HIV infections worldwide. Today it is being considered very strongly that a conceptual microbicidal spermicide can tender protection against pregnancy as well as STDs (including AIDS), simultaneously. However the two activities (spermicidal and microbicidal) need to be integrated in vaginal preparations, as many women across the world may be concerned more about the unwanted pregnancy rather than the STI during a coital act. A strong detergent like nonoxynol-9 (N-9) has been used as a spermicide in many local contraceptive preparations and studies have shown that it also exhibits significant microbicidal activity in vitro. However, recent clinical trials have shown that detergent spermicides do not provide any protection against STDs and AIDS but may in fact even promote their transmission. This anomaly has largely been attributed to their surfactant nature that irritates the vagina and kills the normal vaginal flora making it more susceptible to STD infections. An urgent need for a suitable non-detergent spermicide has thus emerged to replace N-9 in local contraceptive preparations. Anticipating the potential of spermicide-based vaginal contraceptives in the reproductive health of women, a large number of synthetic, non-detergent molecules were designed and evaluated at this Institute over recent years. Simultaneously, a number of natural products from terrestrial plants and marine flora/fauna were also evaluated for spermicidal activity. A local contraceptive preparation incorporating the active ingredient from the fruit pericarp of Sapindus mukorossi has successfully completed Phase III clinical trials in India and is ready for marketing. Recent studies have indicated that in comparison to N-9, this ingredient is much less toxic to Lactobacillus spp. and effectively inhibits the growth of Trichomonas vaginalis in vitro. Other candidate spermicides/microbicides under development worldwide have been reviewed briefly.

Evaluation of local tolerance of the antiretroviral spermicide (WHI-07)-loaded gel-microemulsion in the porcine female reproductive tract

The local tolerance of the antiretroviral spermicide, WHI-07 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate)-loaded gel-microemulsion was evaluated in a physiologically relevant and sensitive porcine model. Gilts (Duroc) in nonestrus stages of the reproductive cycle received either a single or a daily intravaginal application of 2.0% WHI-07 via a gel-microemulsion for 6 days. Cervicovaginal lavage (CVL) fluid was obtained for up to 72 h after a single exposure and the cellular profile and levels of inflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) were quantitated by flow cytometry and chemiluminescence-based multiplex immunoassay, respectively. The reproductive tract (vagina, cervix, uteri and Fallopian tubes) harvested on day 7 was scored histologically for evidence of mucosal irritation using a new scoring criterion for ten histological endpoints that reflect pathological changes in the epithelial/ subepithelial and vascular/perivascular compartments. When compared with irritant reactions caused by the detergent-type spermicide, benzalkonium chloride (BZK), the scatter profile of CVL immune cells and basal levels of proinflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) in CVL fluid were unaffected by intravaginal exposure to 2% WHI-07. Unlike BZK, endpoint histology of the proximal and distal regions of the reproductive tract from gilts treated with 2.0% WHI-07 via gel-microemulsion for 6 days did not result in mucosal irritation or alteration in the epithelium, subepithelium/lamina propria, vessels/perivascular tissues and underlying/surrounding muscles. Based on surrogate markers for inflammation, leukocyte profile and histologic data for local tolerance, repeated intravaginal administration of WHI-07 via gel-microemulsion as a prophylactic contraceptive is unlikely to cause vaginal irritation.

Preclinical evaluation of a dual-acting microbicidal prodrug WHI-07 in combination with vanadocene dithiocarbamate in the female reproductive tract of rabbit, pig, and cat

The mucosal safety of the combination antiretroviral spermicide,WHI-07 [5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxy alaninyl phosphate] and vanadocene dithiocarbamate (VDDTC), was evaluated in 3 different animal models. Twenty-seven NZW rabbits in four subgroups were exposed intravaginally to a gel-microemulsion (GM) with and without three dose levels of WHI-07 plus VDDTC (0.5+0.06%, 1.0+0.12% and 2.0+0.25%) or 4% nonoxynol-9 (N-9; Conceptrol) for 14 consecutive days. Ten nonestrus gilts (Duroc) in three subgroups received either a single or daily intravaginal application of GM with and without 2.0% WHI-07 plus 0.25% VDDTC or 2.0% benzalkonium chloride (BZK)-containing gel for 6 and 4 consecutive days, respectively. Five cats received a single intravaginal application of GM incorporating 2.0% WHI-07 plus 0.25% VDDTC. Genital tract histopathology was performed in the pig and rabbit at the end of dosing period but after 18 weeks post-dosing in the cat. Porcine cervicovaginal lavage (CVL) fluid was obtained for up to 72 hours after a single exposure and changes in the levels of inflammatory cytokines (IL-1beta, IL-8, IFN-gamma, and TNF-alpha) were quantitated by a multiplexed chemiluminescence-based immunoassay. Rabbit vaginal tissues were evaluated for localized cellular inflammation and in situ apoptosis by immunohistochemical staining for CD45, nuclear factor (NF)-kappa B, and terminal deoxynucleotidyl transferase-mediated FITC-deoxyuridine triphosphate nick-end labeling (TUNEL) using confocal laser scanning microscopy (CLSM), respectively. Vanadium content in selected organs and body fluids from rabbits and pigs was determined by atomic absorption spectroscopy. When compared with 4% N-9 (total irritation score 13-14 out of a possible 16), none of the rabbits given WHI-07 plus VDDTC intravaginally, developed histological alterations such as epithelial erosion, edema, leukocyte influx or vascular congestion characteristic of inflammation (total irritation score 4-6). CD45 and NF-kappa B immunoreactivity was limited to cells within the vascular lumen of both control and WHI-07 plus VDDTC-treated vaginal tissues. TUNEL assay revealed lack of increased apoptotic cells in vaginal mucosa exposed to increasing concentrations of WHI-07 plus VDDTC. Basal levels of proinflammatory cytokines (IL-1beta, IL-8, IFN-gamma and TNF-alpha) in porcine CVL were unaffected by intravaginal exposure to WHI-07 plus VDDTC when compared with BZK used as a positive control. Endpoint histology of the reproductive tract from cats and pigs after a single or repeated intravaginal exposure to WHI-07 plus VDDTC, respectively, revealed lack of irritation/inflammation in the epithelium, subepithelium/lamina propria, vessels/perivascular tissues, and underlying/surrounding muscles. Vanadium was not preferentially incorporated into rabbit or porcine tissues and body fluids at levels above 1 microg/g. Based on comparative histologic data and surrogate markers for inflammation, repeated intravaginal administration of WHI-07 plus VDDTC via a gel-microemulsion did not result in vaginal irritation, mucosal toxicity, or systemic absorption of vanadium. Therefore, the combined use of WHI-07 and VDDTC via gel-microemulsion appears safe for topical use as a prophylactic anti-HIV microbicide.

Influence of long-term stability conditions on microbicidal nucleoside prodrug (WHI-07)-loaded gel-microemulsion

The objective of this study was to evaluate the long-term stability of the antiretroviral spermicide WHI-07 (5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxyalaninyl phosphate) in a polymer-based microemulsion. The recovery and stability of WHI-07 in gel-microemulsion was examined by a validated high-performance liquid chromatography (HPLC) method. The stability was examined over a period of 24 weeks at 3 controlled temperatures (4 degrees C, 25 degrees C, and 40 degrees C). The recovery of the prodrug from 0.5% to 2.0% WHI-07-loaded gel-microemulsion was 99.8%. HPLC analysis revealed that a 2% WHI-07-loaded gel-microemulsion stored at room temperature and cold temperatures for 24 weeks retained >90% of the prodrug, whereas those stored at 40 degrees C maintained 90% of initial WHI-07 for at least 10 weeks. The observed stability of WHI-07 in gel-microemulsion is of great importance for its widespread utility in various climatological conditions.

Spermicidal activity of dermaseptins

OBJECTIVE

The present study was undertaken to elucidate the spermicidal efficacy of two synthetic antimicrobial peptides, dermaseptin (DS1 and DS4).

METHODS

Twenty samples of fresh semen were obtained from patients aged between 23 and 35 years. The ability of DS to kill sperm was evaluated by the Sander-Cramer test under in vitro conditions.

RESULTS

The data showed that sperm motility was inhibited with various concentrations of DS at different intervals ranging from 2 to 240 min. The effective 100% inhibitory concentration (EC(100)) of DS4 in 2 min during the sperm immobilization assay was 100 microg/mL whereas the sperm immobilization of EC(100) of DS1 was 200 microg/mL. The presence of 0.1% chelating agent ethylenediaminetetraacetic acid (EDTA) reduced the EC(100) of DS4 to 10 microg/mL whereas less than a two-time enhancement in DS1 activity was observed upon combination with EDTA. The action of DSs on sperm motility was observed to be dose dependent. Supplementation with pentoxifylline and that with calcium are known to enhance the motility of sperm but they did not prevent the spermicidal action of DSs.

CONCLUSION

This present study indicates that DS is an effective agent to kill sperm. In view of this fact, it is suggested that DS4 has antibacterial, antiviral, antifungal and potentially spermicidal activities and could be a potent vaginal contraceptive.

Sophorolipids, microbial glycolipids with anti-human immunodeficiency virus and sperm-immobilizing activities

The increased incidence of human immunodeficiency virus (HIV)/AIDS disease in women aged 15 to 49 years has identified the urgent need for a female-controlled, efficacious, and safe vaginal topical microbicide. To meet this challenge, sophorolipid (SL) produced by Candida bombicola and its structural analogs have been studied in this report for their spermicidal, anti-HIV, and cytotoxic activities. The sophorolipid diacetate ethyl ester derivative is the most potent spermicidal and virucidal agent of the series of SLs studied. Its virucidal activity against HIV and sperm-immobilizing activity against human semen are similar to those of nonoxynol-9. However, it also induced enough vaginal cell toxicity to raise concerns about its applicability for long-term microbicidal contraception. Its structure-activity relationship has been established for creating new analogs with less cytotoxicity and higher activity.

Zidampidine, an aryl phosphate derivative of AZT: in vivo pharmacokinetics, metabolism, toxicity, and anti-viral efficacy against hemorrhagic fever caused by Lassa virus

The pharmacokinetics, metabolism, and toxicity of Zidampidine, an aryl phosphate derivative of AZT, 3'-azidothymidine-5'-[p-bromophenyl methoxyalaninyl phosphate] were investigated in CD-1 mice. Following iv injection, Zidampidine was rapidly converted to its metabolites Ala-AZT-MP and AZT. Zidampidine was not toxic to mice at doses up to 250mg/kg. We next examined the therapeutic effect of Zidampidine in CBA mice challenged with intracerebral injections of the Josiah strain of Lassa virus. Mice were treated either with vehicle or non-toxic doses of Zidampidine administered intraperitoneally 24h prior, 1h prior, and 24, 48, 72, and 96h after virus inoculation. The probability of survival following the Lassa challenge was significantly improved for Zidampidine-treated mice (Kaplan Meier, Log-Rank p value<0.0001). This pilot study provides the basis for future preclinical evaluation of Zidampidine and its potential as a new agent for the treatment of viral hemorrhagic fevers caused by Lassa virus.

PHI-443: A Novel Noncontraceptive Broad-Spectrum Anti-Human Immunodeficiency Virus Microbicide1

PHI-443 (N'-[2-(2-thiophene)ethyl]-N'-[2-(5-bromopyridyl)] thiourea) is a rationally designed novel thiophene thiourea nonnucleoside reverse transcriptase inhibitor (NNRTI) with potent anti-HIV activity against the wild-type and drug-resistant primary clinical human immunodeficiency virus (HIV-1) isolates. This study examined the potential utility of PHI-443 as a nonspermicidal microbicide for prevention of sexual transmission of HIV. Our goal in this study was to test the effects of PHI-443 on in vivo sperm functions under conditions shown to inactivate viruses in human cells. PHI-443 completely prevented the vaginal transmission of a genotypically and phenotypically drug-resistant HIV-1 isolate in the humanized severe combined immunodeficient (Hu-SCID) mouse model of sexually transmitted AIDS. Exposure of human sperm to PHI-443 at doses 30 000 times higher than those that yield effective concentrations against the AIDS virus had no adverse effect on sperm motility, kinematics, cervical mucus penetrability, or the viability of vaginal and cervical epithelial cells. Exposure of rabbit semen to PHI-443 either ex vivo or in vivo had no adverse impact on in vivo fertilizing ability in the rabbit model. Reproductive indices (i.e., pregnancy rate, embryo implantation, and preimplantation losses) were not affected by pretreatment of rabbit semen with PHI-443. Likewise, intravaginal application of 2% PHI-443 via a self-emulsifying gel at the time of artificial insemination resulted in healthy offspring with no apparent peri- or postnatal repercussions. Repeated intravaginal administration of 0.5%- 2% PHI-443 gel was found to be safe in rabbits and lacked systemic absorption. PHI-443 has clinical potential as a prophylactic broad-spectrum anti-HIV microbicide without contraceptive activity.

Antiretroviral spermicide WHI-07 prevents vaginal and rectal transmission of feline immunodeficiency virus in domestic cats

WHI-07 [5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl)-methoxy alaninyl phosphate] is a novel dual-function aryl phosphate derivative of zidovudine with potent anti-human immunodeficiency virus (HIV) and spermicidal activities. WHI-07 was active against the feline immunodeficiency virus (FIV). This study evaluated whether topical application of WHI-07 as a single agent and in combination with an organometallic vanadium complex, vanadocene dithiocarbamate (VDDTC), via a nontoxic gel microemulsion can block vaginal as well as rectal transmission of feline AIDS (FAIDS) by chronically FIV-infected feline T cells in the natural host model. Genital transmission of FIV was monitored in recipient cats by the appearance of viral antibodies to FIV Gag proteins and by virus isolation of blood leukocytes as measured by FIV reverse transcriptase activity and FIV-specific PCR. Microbicidal activity was considered effective when the treated cats did not show evidence of FIV infection for up to 18 weeks postchallenge. An aggregate analysis of 46 specific-pathogen-free cats revealed that a single dose of the infected cell inoculum efficiently transmitted FIV infection when delivered into the vagina (100%) or rectum (66%). Pretreatment of the vagina or rectum with 2% WHI-07 alone or in combination with 0.25% VDDTC significantly (P = 0.004) protected cats from genital transmission by the highly infectious inoculum (7 million FIV(Bangston)-infected feline T cells). Collectively, using the vaginal and rectal transmucosal model for FAIDS, our studies demonstrated that WHI-07 either alone or in combination with a vanadocene has clinical potential for the development of a dual-function anti-HIV microbicide for sexually active women.

Developmental toxicology studies of WHI-07, a novel nucleoside analogue-based dual-function microbicide, administered intravaginally to rabbits

The zidovudine derivative, 5-bromo-6-methoxy-5,6-dihydro-3-azidothymidine-5'-(p-bromophenyl) methoxy alaninyl phosphate (WHI-07), is a dual-function spermicidal and anti-HIV agent with contraceptive and microbicidal activity. In previous subchronic and reproductive toxicity studies and a two-year carcinogenicity study, daily intravaginal application of 0.5 to 2.0% WHI-07 via a gel-microemulsion, was shown to cause no local, systemic and reproductive toxicity or increased carcinogenicity in mice. To evaluate the developmental toxicity potential of WHI-07 in a nonrodent model, subgroups of 20 superovulated NZW rabbits were artificially inseminated and exposed intravaginally to a gel-microemulsion containing 0, 0.5, 1.0, or 2.0% WHI-07 during major organogenesis [gestation days 6-18]. The dose of WHI-07 was equivalent to 1.4x10(6) to 5.7x10(6) times its anti-HIV IC50 and 1400 to 5700 times its spermicidal EC50. Throughout the duration of the experiment (GD 0-29), clinical observations, food consumption, and body weights were recorded. Reproductive and fetal parameters were evaluated following uterotomies on GD 29. Measurements included numbers of corpora lutea, pregnancy, number and distribution of implantations, resorptions, live and dead fetuses, fetal weight, sex ratio, and gross external and skeletal malformations and variations. Maternal food consumption and body weight gain were unaffected by WHI-07 treatment. Hematologic and clinical chemistry determinations on GD 19 and 29 revealed no treatment-related maternal effects. Prior studies of repeated intravaginal administration of WHI-07 gel-microemulsion revealed lack of local toxicity to rabbit vaginal mucosa. In the current study, no drug-related gross lesions were apparent at necropsy. Reproductive indices, ie, pregnancy rate, gravid uterine weights, litter size, number of corpora lutea, implantation sites, pre- and postimplantation losses, viable fetuses, resorptions, fetal body weights, and fetal sex ratio, were not affected by intravaginal exposure to WHI-07. External, and skeletal examinations of fetuses for malformations and variations did not reveal any evidence of teratogenicity in any WHI-07-treated groups. Intravaginal administration of WHI-07 at concentrations as high as 2% did not produce teratogenicity or other developmental toxicity in rabbit conceptus. These findings indicated that WHI-07 shows unique clinical potential to become the active ingredient of a new female-controlled topical microbicidal vaginal contraceptive for women who are at high risk of acquiring HIV/AIDS.

Stampidine is a potential nonspermicidal broad-spectrum anti-human immunodeficiency virus microbicide

OBJECTIVE

Stampidine (2,'3'-didehydro-3'-deoxythymidine-5'-(p-bromophenyl methoxy alaninyl phosphate) is a novel aryl phosphate derivative of stavudine/d4T with broad-spectrum anti-HIV activity in vitro and in vivo. This study investigated the potential utility of stampidine as a nonspermicidal microbicide.

DESIGN

Prospective, controlled study.

SETTING

Center for Advanced Preclinical Sciences and Reproductive Biology Department.

PATIENT(S)

Seven sperm donors.

ANIMAL(S)

Fifty-two sexually mature, female and twenty-four male New Zealand white rabbits.

INTERVENTION(S)

Human semen and genital tract epithelial cells were exposed to stampidine (up to 1 mM). Ovulated does in subgroups of 12 were artificially inseminated with rabbit semen pretreated with stampidine (1 mM) or vehicle. Does in subgroups of four and three, respectively, were exposed intravaginally to a gel or a thermoreversible ovule formulation with and without 0.5%, 1.0%, or 2.0% stampidine (9 to 36 mM) for 14 days.

MAIN OUTCOME MEASURE(S)

Effect of stampidine on human sperm motility, kinematics, penetration through cervical mucus, and epithelial cell viability. Reproductive parameters on gestation day 8. Vaginal tissues were histologically scored 24 hours after dosing.

RESULT(S)

Exposure of human sperm to stampidine even at a concentration 10(6)-times higher than its in vitro anti-HIV-1 activity (50% inhibitory concentration = 1 nM) had no adverse effect on sperm motility, kinematics, cervical mucus penetrability, or the viability of vaginal and endocervical epithelial cells. Reproductive indices of pregnancy rate, embryo implantation, and preimplantation losses were not affected by pretreatment of rabbit semen with stampidine. Gel formulations of 0.5% to 2.0% stampidine (9 to 36 mM) lacked mucosal toxicity.

CONCLUSION(S)

The broad-spectrum anti-HIV agent stampidine had no adverse effect on sperm functions, was not cytotoxic, and did not induce mucosal toxicity. Stampidine has clinical potential as a prophylactic microbicide without contraceptive activity.

A 13-week subchronic intravaginal toxicity study of pokeweed antiviral protein in mice

Pokeweed antiviral protein (PAP), a 29-kDa plant-derived protein isolated from Phytolacca americana, is a broad-spectrum antiviral agent. PAP shows unique clinical potential to become the active ingredient of a non-spermicidal microbicide because of its potent in vivo anti-HIV activity, non-interference with in vivo sperm functions, and lack of cytotoxicity to genital tract epithelial cells. Over 13 weeks the subchronic and reproductive toxicity potential of an intravaginally administered gel formulation of PAP was studied in mice to support its further development as a vaginal microbicide. Female B6C3F1 and CD-1 mice in subgroups of 20, were exposed intravaginally to a gel formulation containing 0, 0.025, 0.05, or 0.1% PAP, 5 days/week for 13 consecutive weeks. On a molar basis, these concentrations are 500- to 2000-times higher than the in vitro anti-HIV IC50 value. After 13 weeks of intravaginal treatment, B6C3F1 mice were evaluated for survival, body weight gain, and absolute and relative organ weights. Blood was analyzed for hematology and clinical chemistry profiles. Microscopic examination was performed on hematoxylin and eosin-stained tissue sections from each study animal. Placebo-control and PAP-dosed female CD-1 mice were mated with untreated males in order to evaluate if PAP has any deleterious effects on reproductive performance. There were no treatment-related mortalities. Mean body weight gain was not reduced by PAP treatment during the dosing period. The hemogram and blood chemistry profiles revealed lack of systemic toxicity following daily intravaginal instillation of PAP for 13 weeks. No clinically significant changes in absolute and relative organ weights were noted in the PAP dose groups. Extensive histopathological examination of tissues showed no increase in treatment-related microscopic lesions in any of the three PAP dose groups. Repeated intravaginal exposure of CD-1 mice to increasing concentrations of PAP for 13 weeks showed no adverse effect on their subsequent reproductive capability (100% fertile), neonatal survival (>90%) or pup development. Collectively, these findings demonstrate that repetitive intravaginal administration of PAP at concentrations as high as 2000 times its in vitro anti-HIV IC50 value was not associated with local or systemic toxicity and did not adversely affect the reproductive performance of mice. PAP may be useful as an active ingredient of a safe vaginal microbicide for prevention of the sexual transmission of viruses, particularly of HIV-1.

Development and evaluation of a thermoreversible ovule formulation of stampidine, a novel nonspermicidal broad-spectrum anti-human immunodeficiency virus microbicide

Stampidine [2',3'-didehydro-2',3'-dideoxythymidine 5'-[p-bromophenyl methoxyalaninyl phosphate], a prodrug of stavudine (STV/d4T) with improved anti-HIV activity, is undergoing development as a novel nonspermicidal microbicide. Here, we report the stability of stampidine as a function of pH, preparation of a novel thermoreversible ovule formulation for mucosal delivery, its dissolution profile in synthetic vaginal fluid, and its mucosal toxicity potential as well as systemic absorption in the rabbit model. Stampidine was most stable under acidic conditions. Stampidine was solubilized in a thermoreversible ovule formulation composed of polyethylene glycol 400, polyethylene glycol fatty acid esters, and polysorbate 80. Does were exposed intravaginally for 14 days to an ovule formulation with and without 0.5%, 1%, or 2% stampidine corresponding to 1 x 107- to 4 x 107-fold higher than its in vitro anti-HIV IC50 value. Vaginal tissues harvested on Day 15 were evaluated for mucosal toxicity and cellular inflammation. Additionally, does were exposed intravaginally to stampidine, and plasma collected at various time points was assayed by analytical HPLC for the prodrug and its bioactive metabolites. Stampidine did not cause mucosal inflammation. The vaginal irritation scores for 0.5-2% stampidine were within the acceptable range for clinical trials. The prodrug and its major metabolites were undetectable in the blood plasma. The marked stability of stampidine at acidic pH, its rapid spreadability, together with its lack of mucosal toxicity or systemic absorption of stampidine via a thermoreversible ovule may provide the foundation for its clinical development as an easy-to-use, safe, and effective broad-spectrum anti-HIV microbicide without contraceptive activity.

Contraceptive activity of a spermicidal aryl phosphate derivative of bromo-methoxy-zidovudine (compound WHI-07) in rabbits

OBJECTIVE

To determine the vaginal contraceptive activity of WHI-07 in the rabbit model.

DESIGN

Prospective, controlled study.

SETTING

Center for advanced preclinical sciences.

ANIMAL(S)

Subgroups of 15, 16, or 24 New Zealand White does and 24 bucks per experiment.

INTERVENTION(S)

Ex vivo (Experiment 1) and in vivo (Experiments 2 and 3) treatment of semen with WHI-07 or Nonoxynol-9 (N-9). In Experiment I, ovulated does in subgroups of 15 were artificially inseminated with semen mixed with WHI-07 or vehicle. In Experiment 2, ovulated does in subgroups of 24 were artificially inseminated within 2 min after intravaginal administration of 2% WHI-07 gel-microemulsion or 2% N-9 gel and allowed to complete term pregnancy. In Experiment 3, ovulated does in subgroups of 16 were artificially inseminated at 15, 30, or 60 minutes.

MAIN OUTCOME MEASURE(S)

The numbers of implanted embryos on postinsemination day 8 or the proportion of does that became pregnant and delivered newborn rabbits; the litter size, weight, growth, and viability of pups until lactation day 5.

RESULT(S)

Exposure of semen to WHI-07 at the time of artificial insemination completely inhibited pregnancy rates (WHI-07-pretreated, 0%, vs. control, 60%) and embryo implantation (WHI-07-pretreated, 0/175 vs. control, 68/170). Intravaginal administration of a 2% WHI-07 gel-microemulsion or 2% N-9 gel before artificial insemination significantly inhibited pregnancy rates (81% and 85% inhibition, respectively) when compared with control. Furthermore, the 2% WHI-07 gel-microemulsion provided >90% inhibition of fertility even when insemination was delayed until 60 minutes after intravaginal application. Rabbits that delivered litters despite intravaginal application of 2% WHI-07 gel-microemulsion had healthy offsprings with no perinatal or postnatal repercussions.

CONCLUSION(S)

WHI-07 is a potent contraceptive agent in vivo. Intravaginal use of WHI-07 gel-microemulsion has clinical potential as a safe prophylactic contraceptive, in addition to its microbicide activity to curb the sexual transmission of HIV.

A 13-week subchronic intravaginal toxicity study of the novel broad-spectrum anti-HIV and spermicidal agent, N-[2-(1-cyclohexenyl)ethyl]-N'-[2-(5-bromopyridyl)]-thiourea (PHI-346) in mice

The nonnucleoside inhibitor (NNI) of HIV-1 reverse transcriptase, PHI-346 (N-[2-(1-cyclohexenyl)ethyl]-N'-[2-(5-bromopyridyl)]-thiourea), is a dual-function spermicidal agent with potent anti-HIV activity against drug-sensitive as well as drug-resistant HIV-1 strains with genotypic and phenotypic NNI resistance. PHI-346 was formulated via a lipophilic gel-microemulsion for intravaginal use as a potential dual-function microbicide. To evaluate the toxicity potential of short-term intravaginal exposure to PHI-346, groups of 15 female B6C3F1 and CD-1 mice were exposed intravaginally to a gel-microemulsion containing 0, 0.5, 1.0, or 2.0% PHI-346, 5 days per week for 13 consecutive weeks. On a molar basis, these concentrations of PHI-346 are 350 to 1,400-times higher than its spermicidal EC50 and nearly 5 x 10(6) to 2 x 10(7) times higher than its in vitro anti-HIV IC50. After 13 weeks of intravaginal treatment, B6C3F1 mice were evaluated for survival, body weight gain, absolute and relative organ weights. Blood was analyzed for hematology and clinical chemistry profiles. Microscopic examination was performed on hematoxylin and eosin-stained tissue sections from each study animal. Placebo control and PHI-346 dosed female CD-1 mice were mated with untreated males in order to evaluate if PHI-346 has any deleterious effects on the reproductive performance. There were no treatment-related mortalities. Mean body weight gain during the dosing period was not reduced by PHI-346 treatment. The hemogram or blood chemistry profiles revealed lack of systemic toxicity following daily intravaginal instillation of PHI-346 for 13 weeks. No clinically significant changes in absolute and relative organ weights were noted in PHI-346 dose groups. Extensive histopathological examination of tissues revealed no treatment-related abnormalities in any of the three PHI-346 dose groups. Repeated intravaginal exposure of CD-1 mice to increasing concentrations of PHI-346 for 13 weeks had no adverse effect on their subsequent reproductive capability, perinatal outcome, growth, and development of offspring. Collectively, these findings demonstrate that repetitive intravaginal administration of PHI-346 at concentrations as high as 1,400-times its spermicidal EC50 and 2 x 10(7) times its in vitro anti-HIV IC50 was not associated with local or systemic toxicity and did not adversely affect the reproductive performance in mice. PHI-346 may be useful as an active ingredient of a safe vaginal microbicide for prevention of the sexual transmission of multidrug-resistant HIV-1.

Two-year toxicity and carcinogenicity studies in B(6)C(3)F(1) mice with 5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl) methoxyalaninyl phosphate (WHI-07), a novel anti-HIV and contraceptive agent

The zidovudine derivative, 5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl) methoxy alaninyl phosphate (WHI-07), is a dual-function spermicidal and anti-HIV agent with contraceptive and microbicidal activity. In previous two subchronic toxicity studies, intravaginal application of 0.5-2.0% WHI-07, for up to 13 weeks, was shown to cause no local, systemic or reproductive toxicity. To evaluate the toxicity and carcinogenic potential of long-term exposure to WHl-07, groups of 50 female B(6)C(3)F(1) mice were given no treatment or exposed intravaginally to a gel-microemulsion formulation with and without 2.0% WHI-07, 5 days per week for 2 years. The dose of WHI-07 was equivalent to 5700 times its spermicidal EC(50) and 5.7x10(6) times its anti-HIV IC(50). The endpoints that were evaluated included survival, body weight, hematologic and clinical chemistry profiles, absolute and relative organ weights, and histopathology. No significant differences in mean body weight gain and survival were found among the groups of untreated control, placebo control, and 2% WHI-07-treated mice at the end of the 2-year study. The hematological and clinical chemistry profiles did not reveal any toxicologically significant changes that could be attributed to WHI-07 treatment. No clinically significant changes in absolute and relative organ weights were noted in the WHI-07 group. A variety of neoplastic and nonneoplastic lesions which were considered incidental, related to aging, or procedural, were observed in both the untreated and intravaginally treated groups. The proportion of animals with malignant tumors, the total number of malignant tumors, as well as the types of malignant tumors in the three groups was similar. The cumulative incidence of microscopic lesions in various organs showed that malignant lymphoma was the major cause of death in aging female B(6)C(3)F(1) mice, the incidence of which was unaffected by intravaginal treatment. We conclude that long-term intravaginal administration of WHI-07 is not associated with systemic toxicity or increased carcinogenicity in mice. WHI-07 has clinical potential as an active ingredient of a safe vaginal/rectal microbicide.

Considerations and development of topical microbicides to inhibit the sexual transmission of HIV

The increased incidence of HIV/AIDS disease in women aged 15 - 49 years has identified the urgent need for a female-controlled, efficacious and safe vaginal topical microbicide. To meet this challenge, new topical microbicide candidates consisting of molecules or formulations that modify the genital environment (BufferGel, engineered Lactobacillus, over-the-counter lubricants), surfactants (C31D/Savvy, sodium dodecyl sulfate, sodium lauryl sulfate), polyanionic polymers (PRO 2000, beta-cyclodextrin, Carraguard, CAP, D2S, SPL-7013), proteins (cyanovirin-N, monoclonal antibodies, thromspondin-1 peptides, Pokeweed antiviral protein and others), reverse transcription inhibitors (PMPA [Tenofovir ]), UC-781, SJ-3366, DABO and thiourea) and other molecules (NCp7-specific virucides, chemokine receptor agonists/antagonists, WHI-05 and WHI-07) are currently being investigated for activity, safety and efficacy. This review will assess the development of these molecules in the context of cervicovaginal defences and the clinical failure of nonoxynol-9.

The Development of Microbicides for Clinical Use to Prevent Sexually Transmitted Diseases

Approximately 60 vaginal microbicides are under development for the prevention of HIV/AIDS and other sexually transmitted pathogens. The history and current status of the field are discussed with emphasis on the lessons learned from recent clinical trials, along with an emphasis on the mechanisms involved in the sexual transmission of HIV and how this information influences microbicide development. Additionally, the current status of in vitro and animal systems used for evaluating microbicide efficacy, as well as the challenges involved in developing more appropriate and practical assays, are discussed. Also discussed are the challenges that face the microbicide product development field in meeting US Food and Drug Administration requirements regarding product safety and stability.

Gel-microemulsions as vaginal spermicides and intravaginal drug delivery vehicles

There is a need for novel formulations to improve the bioavailability through the vaginal/rectal mucosa of microbicidal drug substances against sexually transmitted diseases. In addition, there is a need for more effective and less toxic vaginal spermicides. Here we review our recent discovery of novel gel-microemulsions (GM) as nontoxic, dual-function intravaginal spermicides, which can be used as delivery vehicles for lipophilic drug substances targeting sexually transmitted pathogens. We describe the formulation and biologic properties of 2 novel, submicron-particle-size GMs, GM-4 and GM-144, which were prepared from commonly available pharmaceutical excipients. These GMs comprising oil-in-water microemulsion and polymeric hydrogels were designed to solubilize lipophilic antiviral/antimicrobial agents and exhibited rapid spermicidal activity in human semen. Preclinical studies comparing the in vivo contraceptive efficacy of GM-4 and GM-144 versus nonoxynol-9-based detergent spermicide (Gynol II) in the rigorous rabbit model confirmed the potent contraceptive activity of these GMs. Unlike nonoxynol-9, repeated intravaginal applications of GM-4 and GM-144 in the rabbit vaginal irritation test were not associated with local inflammation or damage of the vaginal mucosa or epithelium. Furthermore, in short-term toxicity studies performed in mice, repetitive intravaginal application of spermicidal GM-4 and GM-144 for up to 13 weeks was not associated with any local, systemic, or reproductive toxicity. Spermicidal GMs have unprecedented potential as dual function microbicidal contraceptives to improve vaginal bioavailability of poorly soluble antimicrobial agents without causing significant vaginal damage.

Lack of adverse effects on fertility of female CD-1 mice exposed to repetitive intravaginal gel-microemulsion formulation of a dual-function anti-HIV agent: aryl phosphate derivative of bromo-methoxy-zidovudine (compound WHI-07)

5-bromo-6-methoxy-5,6-dihydro-3(')-azidothymidine-5(')-(p-bromophenyl) methoxyalaninyl phosphate (WHI-07), a novel bromo-methoxy-substituted aryl phosphate derivative of zidovudine (ZDV), is a potent dual-function contraceptive agent with anti-HIV activity. Its potential for reproductive toxicity was assessed in a series of experiments using CD-1 mice under the conditions of its intended use as an intravaginal microbicide. Female CD-1 mice were exposed intravaginally to a gel-microemulsion formulation containing 0%, 0.5%, 1.0% or 2.0% WHI-07 for up to 13 weeks. On a molar basis, these concentrations represent 1400-5700 times its in vitro spermicidal IC(50) and 1.4-5.7(x10(6)) times its in vitro anti-HIV IC(50). We examined the effects of intravaginally administered WHI-07 on: ovulation efficiency; in vivo fertilization and early embryonic, fetal development; and reproductive outcome, including neonatal survival and pup development. Compound WHI-07 was administered intravaginally during superovulation, organogenesis and prior to mating for 5 and 10 consecutive days and for 13 weeks, respectively. Mice were evaluated for ovulation efficiency and fertilization rate and cleavage 14 and 40 h after human chorionic gonadotropin (hCG) injection, respectively. Pregnant mice were administered 2% WHI-07 intravaginally during gestation days (GD) 6-15 and measures of teratogenicity were evaluated on GD 17. For short-term toxicity study, mice were given intravaginal treatment of gel-microemulsion containing 0%, 0.5%, 1.0% and 2.0% WHI-07 for 13 weeks and then mated with untreated males to evaluate potential reproductive and developmental effects. Repeated intravaginal exposure of mice to 2% WHI-07 had no adverse effects on ovulation response, mean number of eggs recovered or the percentage of eggs fertilized or cleaved. No evidence of reproductive toxicity, fetal toxicity or teratogenicity was found following repetitive intravaginal application of 2% WHI-07 during the period of organogenesis. Furthermore, repeated intravaginal exposure of mice to 0.5-2.0% WHI-07 for 13 weeks had no adverse effect on the subsequent reproductive capability, perinatal outcome or growth and development of the offspring. Compound WHI-07 shows unique clinical potential as a safe, dual-function vaginal contraceptive for curbing mucosal and perinatal HIV transmission.

GM-144, a novel lipophilic vaginal contraceptive gel-microemulsion

In a systematic effort to develop a dual-function intravaginal spermicide as well as a drug delivery vehicle against sexually transmitted pathogens, a submicron particle size (30-80 nm), lipophilic and spermicidal gel-microemulsion (viz GM-144) containing the pharmaceutical excipients propylene glycol, Captex 300, Cremophor EL, Phospholipon 90G, Rhodigel, Pluronic F-68, and sodium benzoate was formulated. GM-144 completely immobilized sperm in human or rabbit semen in less than 30 seconds. Therefore, the in vivo contraceptive potency of intravaginally applied GM-144 was compared in the standard rabbit model to those of the detergent spermicide, nonoxynol-9 (N-9)-containing formulation. Eighty-four ovulated New Zealand White rabbits in subgroups of 28 were artificially inseminated with and without intravaginal administration of GM-144 or 2% N-9 (Gynol II) formulation and allowed to complete term pregnancy. GM-144 showed remarkable contraceptive activity in the rigorous rabbit model. When compared with control, intravaginal administration of GM-144 and Gynol II resulted in 75% and 70.8% inhibition of fertility (P <.0001 versus control, Fisher's exact test), respectively. Thus, GM-144 as a vaginal contraceptive was as effective as the commercially available N-9 gel. In the rabbit vaginal irritation test, none of the 6 rabbits given daily intravaginal application of spermicidal GM-144 for 10 days developed epithelial ulceration, edema, leukocyte influx, or vascular congestion characteristic of inflammation (total score = 5). Therefore, GM-144 has the potential to become a clinically useful safe vaginal contraceptive and a vehicle for formulating lipophilic drugs used in reducing the risk of heterosexual transmission of sexually transmitted diseases.

Contraceptive efficacy and safety studies of a novel microemulsion-based lipophilic vaginal spermicide

OBJECTIVE

To investigate the in vivo contraceptive potency and safety of a novel microemulsion-based lipophilic vaginal spermicide.

DESIGN

In vitro and in vivo spermicidal activity and safety of a submicron-particle-size, lipophilic gel-microemulsion (GM-4).

SETTING

Center for Advanced Preclinical Sciences at the Parker Hughes Institute.

PATIENT(S)

Nine male volunteer sperm donors.

INTERVENTION(S)

Motile human sperm in semen and medium were exposed to eight GM-4 components or GM-4 formulation. Forty-eight ovulated NZW rabbits in subgroups of 16 with or without intravaginal administration of GM-4 or nonoxynol-9 gel (N-9; Gynol II) were artificially inseminated and allowed to complete pregnancy. Eleven rabbits were exposed to daily intravaginal application of GM-4 with and without N-9 for 10 consecutive days. Ten of 20 B(6)C(3)F(1) mice were given repetitive intravaginal application of GM-4 for 5 days/week over 13 consecutive weeks.

MAIN OUTCOME MEASURE(S)

The motility of human sperm treated with GM-4 components and GM-4. Term pregnancy in rabbits and histopathological grading of rabbit vaginal tissue for irritation. Evaluation of mice for survival, growth, hematologic parameters, blood-chemistry profiles, absolute and relative organ weights, and histopathology.

RESULT(S)

The individual components of GM-4 lacked spermicidal activity in human semen, whereas the GM-4 formulation containing all the eight pharmacological excipients exhibited potent spermicidal activity with rapid kinetics. GM-4 showed remarkable contraceptive activity in the rigorous rabbit model. None of the 16 (0%) rabbits given GM-4 intravaginally before artificial insemination became pregnant. By contrast, 15 of 16 (93.7%) control rabbits and 5 of 16 (31.2%) Gynol II-treated rabbits became pregnant and delivered newborns. Thus, GM-4 was a significantly more effective contraceptive than a commercially available N-9 gel [100% vs. 68.7% protection; P< 0.05, Fisher's exact test]. Unlike the rabbits treated with N-9, none of the rabbits that were given GM-4 intravaginally for 10 consecutive days developed epithelial ulceration, edema, leukocyte influx, or vascular congestion characteristic of inflammation. Furthermore, repeated intravaginal application of GM-4 for up to 13 weeks in mice had no adverse effects on survival, growth, metabolism, or organ function.

CONCLUSION

We conclude that the novel spermicidal GM-4 formulation is safe and significantly more effective than N-9 in preventing conception.

Thymidine kinase-independent intracellular delivery of bioactive nucleotides by aryl phosphate derivatives of bromo-methoxy zidovudine (compounds WHI-05 and WHI-07) in normal human female genital tract epithelial cells and sperm

The compounds WHI-05 (5-bromo-6-methoxy-5, 6-dihydro-3'-azidothymidine-5'-[p-methoxyphenyl] methoxyalaninyl phosphate) and WHI-07 (5-bromo-6-methoxy-5, 6-dihydro-3'-azidothymidine-5'-[p-bromophenyl] methoxyalaninyl phosphate) are aryl phosphate derivatives of zidovudine (ZDV) with dual-function anti-human immunodeficiency virus and contraceptive activity. These drugs were rationally designed to bypass the thymidine kinase (TK) dependency of ZDV activation as well as to achieve spermicidal activity. We investigated the TK activity and intracellular metabolism of WHI-05 and WHI-07 in normal human vaginal and cervical epithelial cells as well as sperm. The time- and concentration-dependent intracellular formation of ZDV metabolites following addition of WHI-05 and WHI-07 to normal human vaginal, ectocervical, and endocervical epithelial cells as well as motile sperm was studied by analytical HPLC. Thymidine kinase activity in these cells was determined by the flow cytometric method based on intracellular phosphorylation of the fluorescent nucleoside, 5-amino-2-deoxyuridine-dansyl chloride and by the ability of cell-free extracts to convert [(3)H]thymidine to thymidine monophosphate in comparison to NALM-6, a pre-B leukemia cell line. TK activity of genital tract epithelial cells and sperm was found to be relatively low or lacking. Addition of WHI-05 and WHI-07 to vaginal and cervical epithelial cells resulted in their concentration- and time-dependent conversion to alaninyl ZDV monophosphate (Ala-ZDV-MP) and 5'-ZDV monophosphate as the major metabolites. Studies using motile human sperm also demonstrated the conversion of WHI-05 and WHI-07 to Ala-ZDV-MP. These results demonstrate that human female genital tract epithelial cells and sperm efficiently convert WHI-05 and WHI-07 to bioactive ZDV metabolites despite their TK deficiency.

Pokeweed antiviral protein: a potential nonspermicidal prophylactic antiviral agent

OBJECTIVE

To investigate the effects of pokeweed antiviral protein (PAP), a 29-kDa anti-human immunodeficiency virus (HIV) protein purified from the leaves of Phytolacca americana, on human sperm function.

DESIGN

Prospective, controlled study.

SETTING

Reproductive biology department.

PATIENT(S)

Seven sperm donors.

INTERVENTION(S)

Human sperm and female genital tract epithelial cells were exposed to PAP ranging in concentration from 1 to 1,000 microg/mL.

MAIN OUTCOME MEASURES

Effect of PAP on sperm motility, kinematics, and sperm penetration through bovine mucus, as well as binding, penetration, and fusion of zona-free hamster eggs.

RESULTS

Exposing human sperm to PAP (IC(50) p24 = 14 +/- 2 nM) did not affect sperm motility and kinematics over a dose range of 1 to 1,000 microg/mL. Treating sperm with either 100 or 1,000 microg/mL of PAP had no effect on cervical mucus penetrability, nor did it affect sperm binding, penetration, and fusion of zona-free hamster eggs. PAP was noncytotoxic to genital-tract epithelial cells.

CONCLUSIONS

The broad-spectrum antiviral agent PAP was nontoxic to human sperm and female genital tract epithelial cells even at a concentration 2,000 times higher than its IC(50) value against HIV-1. PAP has particular clinical usefulness both as a nonspermicidal intravaginal microbicide and as a prophylactic antiviral agent that can inactivate infective viruses and virus-infected cells in semen before assisted reproductive technology procedures are undertaken.

Novel thiourea compounds as dual-function microbicides

Sexually active women represent the fastest growing human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome risk group. In an effort to develop a vaginal microbicidal contraceptive potentially capable of preventing HIV transmission as well as providing fertility control, we previously reported the synthesis of novel nonnucleoside inhibitors (NNIs) of HIV-1 reverse transcriptase with sperm-immobilizing activity (SIA). To gain further insight into the structure-function relationship controlling these two properties of NNIs, we have rationally designed and synthesized 30 novel thiourea compounds and examined them for dual-function, anti-HIV and spermicidal activity. Twelve of the 30 thiourea compounds exhibited potent anti-HIV activity in the nanomolar range (IC(50) = <1-9 nM). Nine of the 30 thiourea derivatives exhibited both anti-HIV and spermicidal activity. Among the phenyl ring-containing thioureas, the 2-fluoro (HI-240) -substituted and 2-chloro (HI-253) -substituted derivatives exhibited potent anti-HIV activity (IC(50) = <1 nM) with SIA (EC(50) = 70 microM and 147 microM). Among the alicyclic ring-containing thioureas, the 5-bromo (HI-346) and 5-chloro (HI-445) functionalized cyclohexenyl ring-substituted thioureas were the most potent dual-function spermicides (EC(50) = 42 and 57 microM), with anti-HIV activity at nanomolar range (IC(50) = 3 nM). Unlike nonoxynol-9 (N-9), none of the potent dual-function thiourea compounds were cytotoxic to normal human vaginal, ectocervical, and endocervical epithelial cells at spermicidal concentrations. We conclude that as potent anti-HIV agents with SIA and reduced cytotoxicity when compared with N-9, the phenyl-substituted and cyclohexenyl-substituted thiourea derivatives, especially compounds HI-253 (N-[2-(2-chlorophenethyl)]-N'-[2-(5-bromopyridyl)-thiourea), HI-346 (N-[2-(5-bromopyridinyl)]-N'-[2-(1-cyclohexenyl)ethyl-thiourea), and HI-445 (N-[2-(5-chloropyridinyl)]-N'-[2-(1-cyclohexenyl)ethyl-thiourea) show unique clinical potential to become the active ingredients of a vaginal contraceptive for women who are at high risk for acquiring HIV by heterosexual vaginal transmission.

Evaluation of subchronic (13-week) and reproductive toxicity potential of intravaginal gel-microemulsion formulation of a dual-function phenyl phosphate derivative of bromo-methoxy zidovudine (compound whi-07) in B(6)C(3)F(1) mice

Heterosexual transmission of human immunodeficiency virus (HIV) accounts for 90% of all new infections worldwide and significantly contributes to new acquired immunodeficiency syndrome (AIDS) cases in the USA. In a systematic effort to develop a microbicidal contraceptive capable of preventing HIV transmission as well as providing fertility control, we previously identified novel phenyl phosphate derivatives of 3'-azido-3'-deoxythymidine (zidovudine) that exhibit potent anti-HIV and spermicidal activities. This study reports the preclinical studies of our lead compound WHI-07, 5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-bromophenyl) methoxyalaninyl phosphate, for use as a dual-function topical microbicide. In vivo toxicity studies in non-human primates and rodents given WHI-07 (20 mg kg(-1)) intravenously and intraperitonealy, respectively, had no detectable adverse effects on hematological and clinical chemistry profiles. The 13-week subchronic and reproductive toxicity potential of an intravaginal gel-microemulsion formulation of WHI-07 was studied in mice to support its further development as a dual-function microbicide. Groups of ten female B(6)C(3)F(1) mice were exposed intravaginally to a gel-microemulsion formulation containing 0, 0.5, 1.0 or 2.0% WHI-07, 5 days a week, for 13 consecutive weeks. On a molar basis, these concentrations represent 1400-5700 times their in vitro spermicidal potency EC(50)) and 1.4 x 10(6)-5.7 x 10(6) times their in vitro anti-HIV activity(50)). After 13 weeks of intravaginal treatment, half of the treated mice were evaluated for toxicity and the other half were mated with untreated males to evaluate potential reproductive and developmental effects. The endpoints that were evaluated included survival, body weight gain, hematological and clinical chemistries, absolute and relative organ weights and histopathology. The WHI-07 applications did not cause weight loss, morbidity, mortality or specific tissue lesions detectable by histopathology. Repeated intravaginal exposure of mice to WHI-05 for 13 weeks had no adverse effects on subsequent reproductive performance (100% fertile), neonatal survival (>95%) or pup development. These findings collectively show that the experimental dual-function anti-HIV and contraceptive agent WHI-07 did not cause significant acute or subchronic toxicity.

Importance of the alanine methyl ester side chain for the biological activity profile of dual-function phenyl phosphate derivatives of bromo-methoxy-zidovudine

In a systematic search for developing a virucidal spermicide with potent anti-human immunodeficiency virus (HIV) and spermicidal activities, we synthesized and evaluated 14 phosphoramidate derivatives of 5-bromo-6-methoxy-zidovudine (PP-BMZ) with differing amino acid ester side chains and para substitutions on the phenyl moiety. Anti-HIV activity was tested by measuring viral p24 antigen production as a marker of viral replication in HIV-1-infected human peripheral blood mononuclear cells. The effect of various PP-BMZ compounds on human sperm motion kinematics was analysed by computer-assisted sperm analysis. Varying the Ala side chain of the phosphoramidate group to other non-polar amino acids, including the cyclic amino acids proline and tryptophan, led to significant alterations in both anti-HIV and spermicidal activities. Our findings highlight the necessity of the Ala side chain and the presence of an electron-withdrawing para-bromo substituent on the phenyl moiety in addition to the bromo-methoxy functional groups on the thymine ring for the PP-BMZ compounds to be effective virucidal spermicides. These membrane permeable dual-function nucleoside analogues may provide the basis for a new strategy aimed at prevention of the sexual transmission of HIV while providing fertility control for women.

Structural requirements for potent human spermicidal activity of dual-function aryl phosphate derivative of bromo-methoxy zidovudine (compound WHI-07)

WHI-07, a novel bromo-methoxy-substituted aryl phosphate derivative of zidovudine (ZDV), is a potent dual-function contraceptive agent. Although the bromo-methoxy functional groups in the thymine ring of its ZDV are very important for its sperm-immobilizing activity (SIA), the importance of the esterification of the phosphate group with an amino acid side chain and the identity of the para substituent in the aryl moiety remain unclear. In the present study, we have synthesized 23 new analogues of WHI-07 by replacing the alanine (Ala) side chain with different amino acids containing nonpolar side chains, namely tryptophan (Trp), proline (Pro), phenylalanine (Phe), leucine (Leu), methionine (Met), valine (Val), or glycine (Gly). The para substituents on the aryl moiety included bromo, chloro, fluoro, nitro, or methoxy groups. The SIA of each of the 23 WHI-07 analogues was evaluated by computer-assisted sperm analysis. The potential cytotoxicity of these compounds against normal human ectocervical and endocervical epithelial cells was evaluated using MTT (3-[4, 5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) cell viability assays. The replacement of the Ala side chain of WHI-07 with Val, Leu, or Phe led to a complete loss of SIA (EC(50) values > 500 microM), whereas replacement with Trp reduced the SIA by 4-fold. The presence of para substituents on the phenyl moiety led to significant alterations in SIA. The anti-human immunodeficiency virus (HIV) activity of Trp-containing WHI-07 analogues was also diminished. Our finding highlights the necessity of Ala side chain and the presence of electron-withdrawing para-bromo substituent on the phenyl moiety in addition to bromo-methoxy functionalization groups on the thymine ring in order for the phosphoramidate derivatives of ZDV to be effective dual-function spermicidal agents. Unlike the detergent-type microbicide, nonoxynol-9, which was cytotoxic to normal human ectocervical and endocervical epithelial cells (IC(50) values of 22 microM and 16 microM, respectively) at spermicidal concentrations (EC(50) = 81 microM), WHI-07 and its active analogues were selectively spermicidal without cytotoxicity against female genital tract epithelial cells. WHI-07 and its Trp analogues hold particular clinical promise for the development of novel, nondetergent-type prophylactic contraceptives for the prevention of heterosexual HIV/acquired immunodeficiency syndrome transmission.

Evaluation of subchronic (13 weeks) and reproductive toxicity potential of intravaginal gel-microemulsion formulation of a dual-function phenyl phosphate derivative of bromo-methoxy zidovudine (compound WHI-05) in B(6)C(3)F(1) mice

Heterosexual transmission of human immunodeficiency virus (HIV) accounts for 90% of all new infections worldwide and significantly contributes to new acquired immunodeficiency syndrome (AIDS) cases in the United States. In a systematic effort to develop a microbicidal contraceptive capable of preventing HIV transmission as well as providing fertility control, we previously identified novel phenyl phosphate derivatives of 3'-azido-3'-deoxythymidine (zidovudine) which exhibit potent anti-HIV and spermicidal activities. This study reports the preliminary preclinical study of our lead compound WHI-05, 5-bromo-6-methoxy-5, 6-dihydro-3'-azidothymidine-5'-(p-methoxyphenyl) methoxyalaninyl phosphate, for use as a dual-function topical microbicide. Acute toxicity studies have shown that WHI-05 has no detectable adverse effects on laboratory animals. The 13-week subchronic and reproductive toxicity potential of intravaginal gel-microemulsion formulation of WHI-05 were studied in mice to support its further development as a virucidal spermicide. Groups of 10 female B(6)C(3)F(1) mice were exposed intravaginally to a gel-microemulsion formulation containing 0%, 0.5%, 1.0%, or 2.0% WHI-05, 5 days/week for 13 consecutive weeks. On a molar basis, these concentrations represent 300 to 1200 times their in vitro spermicidal potency, and 1.5x10(4) to 6.1x 10(4) times their in vitro anti-HIV activity. After 13 weeks of intravaginal treatment, one half of treated mice were evaluated for toxicity, and the other half were mated with untreated males to evaluate potential reproductive and developmental effects. Repetitive intravaginal application of WHI-05 to yield a local concentration 6.1x10(4) times higher than its in vitro HIV IC(50) value and 1200 times higher than its spermicidal EC(50)96%), or pup development. These findings collectively show that the experimental dual-function anti-HIV and contraceptive agent, WHI-05, did not cause significant acute or subchronic and reproductive toxicity under the test conditions.

WHI-05, a novel bromo-methoxy substituted phenyl phosphate derivative of zidovudine, is a dual-action spermicide with potent anti-HIV activity

Heterosexual transmission of HIV to women is the fastest-growing mode of transmission. In a systematic effort to develop a microbicide capable of preventing HIV transmission as well as providing fertility control, novel phenyl phosphate derivatives of 3'-azido-3'-deoxythymidine (zidovudine, ZDV) have been identified that exhibit potent anti-HIV and spermicidal activities. This study reports the synthesis, characterization, and preclinical formulation of compound WHI-05, 5-bromo-6-methoxy-5,6-dihydro-3'-azidothymidine-5'-(p-methoxyphenyl) methoxyalaninyl phosphate. The anti-HIV activities of WHI-05 and ZDV were compared by measuring p24 antigen production and reverse transcriptase activity as markers of viral replication using human peripheral blood mononuclear cells (PBMC) infected with both ZDV-sensitive and ZDV-resistant strains of HIV. The sperm immobilizing activity (SIA) of WHI-05 was compared with that of ZDV and nonoxynol-9 (N-9) by computer-assisted sperm analysis (CASA). The effect of WHI-05 on sperm membrane integrity was examined by high resolution, low voltage scanning electron microscopy (HR-LVSEM). The in vitro cytotoxicity profile of WHI-05 versus N-9 were compared using normal human vaginal, ectocervical, and endocervical epithelial cells. The in vivo vaginal tolerance, absorption, and toxicity of a 2% WHI-05 gel-microemulsion was tested in the rabbit. Whereas ZDV displayed potent anti-HIV activity but lacked SIA, WHI-05 elicited both potent anti-HIV activity and SIA. WHI-05 inhibited the replication of ZDV-sensitive as well as ZDV-resistant strains of HIV in PBMC. CASA combined with HR-LVSEM demonstrated that WHI-05-induced SIA was not associated with membrane damage. Unlike, N-9, the spermicidal activity of WHI-05 was not associated with cytotoxicity to reproductive tract epithelial cells. Repetitive intravaginal application of a 2% WHI-05 gel-microemulsion did not damage the vaginal epithelium or cause local inflammation in the rabbit model. As a potent anti-HIV agent that has spermicidal activity and is devoid of mucosal toxicity, WHI-05 shows a unique clinical potential to become the active ingredient for a vaginal contraceptive for women who are at high risk for acquiring HIV by heterosexual vaginal transmission.