CA2113218A1 - Method of using lectins for contraception and prophylaxis against diseases transmittable by sexual contact and apparatus for administering lectins - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
In order to prevent conception and/or the spread of sexually transmitted diseases (STD'S) one or more lectins capable of binding sperm and/or the pathogenic microorganisms responsible for STD'S are administered to the vagina prior to sexual intercourse. The lectins immobilize the sperm to render them incapable of fertilization and also bind to the microorganisms to render them non-pathogenic or to the cells to prevent infection by the microorganisms.
The invention also encompasses a device for to be placed in the vault of the vagina which comprises a ring which surrounds the cervix and a membrane spanning the central aperture of the ring to prevent the direct contact of ejaculate with the cervical tissues. The device is impregnated or coated with lectins and releases them into the vaginal environment over a period of time.

Description

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~6825-00002 PATENT APPLICATION

TITLE: METHOD OF USING LECTINS FOR CONTRACEPTION AND
PROPHYLAXIS AGAINST DISEASES TRANSMITTABLE BY SEXUAL
CONTACT AND APPARATUS FOR ADMINISTERING LECTINS

BACKGROUND OF THE INVENTION

1. Field of the invention:
This invention relates generally to methods of contraception and prophylaxis against diseases transmittable by sexual contact and more particularly to a method using intravaginally administered lectins for contraception and to protect against the transmission of diseases that are transmissible by sexual contact. The invention also relates to devices for intravaginal administration of lectins.

2. Brief SummarY of the Prior Art Sexually transmitted diseases (STD's) are epidemic in this country and worldwide. Furthermore, other diseases that have not traditionally been considered to be STD's have also been found to be transmitted by sexual contact, e.g., hepatitis B. The medical and public health problems assoc~ated with these epidemics have motivated a search for methods of controlling these diseases by , limit~ng their transmission from per~on to person. Similarly, `.,~
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although many methods of contraception have been employed, no universally satisfactory method has been developed.
Hitherto it has been generally agreed that barrier methods which prevent the contact of body fluids between individuals are the most effective means of preventing transmission of such diseases. Such barrier methods are also effective contraceptive procedures. However, such methods are somewhat inconvenient and require some cooperation between individuals.
An alternative method for preventing the transmission of sexually transmitted diseases is to kill the pathogenic microorganisms in semen and vaginal secretions so that they are incapable of invading the tissues and causing the disease. While intravaginally placed spermatocides have been used for contraception, alone or in combination with barrier methods, antimicrobial materials have not been so used to prevent STD's, probably because many of such materials are irritating to adjacent tissues.
Administration of biologically active materials to the vagina for whatever purpose is usually accomplished by the use of some device that provides for convenient application of the medication by the user herself. A variety of devices exist for delivery of bioactive substances such as spermatocides and various medications. Each has its place in the medical armamentarium but each has certain deficiencies for application of contraceptive or anti-microbial agents in the context of sexual activity. Conventional vaginal suppositories and ovules ~3 ~32~

may not provide medication to the entire vagina because of their shape and placement by the user in the vagina. Such suppositories are generally comprised of a material that melts at body temperature to allow the medication to spread and contact the tissues. However, when the dosage form melts, the medication may drain out of the vagina rather quickly, thus minimizing its potential effectiveness and significantly reducing the extended exposure of the tissues and pathogens to the medication which is often necessary for effective treatment. Similarly, the effective duration of contraceptives applied in this way tends to be relatively brief. In addition, such delivery vehicles, even when freshly applied, do not provide any physical barrier to deposition of male ejaculate on the cervix. Such ready access of sperm to the cervix may allow them to escape the action of spermatocides that are diffused throughout the vagina.
Furthermore, because cells at the cervix are uniquely sensitive to several pathogens such as chlamydia trachomatis, the absence of a barrier deprives these cells of a significant means of protection.
In order to provide for a longer retention of medication in the vagina and assure a more continuous delivery of active ingredients t:o the tissue, several types of vaginal rings have been proposed. Such devices are disclosed, for example, in Duncan, U.S. Patent 3,545,439; Roseman, U.S. Patent 3,920,805;
Schopflin, U.S. Patents 4,012,496 and 4,012,497; Wong et al., U.S. Patents 4,237,885 and 4,286,587; and Nash et al., U.S.

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~atent 4,292,965. The vagin~l rings are ~enerally impregnated with a spermatocide and are designed to be retained in the vaginal vault and to release the spermatocide slowly over a period of time to maintain an effective contraceptive concentration of the active material in the vagina. However, such devices do not prevent the direct contact of ejaculate with the tissues of the cervix, and there~ore do not protect those tissues from contact with pathogenic organisms which might be contained in the ejaculate. They are also of questionable efficacy in supplying the spermatocide where it is most needed. ~
Another approach is to use a cervical cap or a diaphragm to ;
serve as a mechanical barrier to the sperm and to dispense medication. These devices are designed for a relatively tight fit either to the cervix or the walls of the vagina to serve as a mechanical barrier to the passage of sperm. Such devices can be effective, especially as contraceptives and when combined with spermatocides. However, because of the need to provide a sperm-resistant seal they are frequently relatively complex devices incorporating metallic springs within a rubber or synthetic resin structure to provide the required sealing force.
Another approach to providing an effective concentration of spermatocide in the vagina is to provide a sponge impregnated with a spermatocide. Such applicators are not intended to be precisely located and may permit the contact of ejaculate with the tissues of the cervix, with the undesirable consequences outlined above.

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Accordingly, a neec~ has continued to exist for a method of contraception and prophylaxis against STD's by vaginal administration of a spermatocide and/or antimicrobial material, and for a simple and effective device to protect the tissues at S risk from contact with microorganisms while dispensing a spermatocidal and/or antimicrobial material~

SUMMA~Y OF THE INVENTION
This need has now been alleviated by the method and device of this invention, according to which one or more lectins capable of binding sperm and/or the pathogenic microorganisms responsible for STD's are administered to the vagina or site of infection prior to sexual intercourse. The lectins immobilize sperm to render them incapable of fertilizatiGn and also bind to the microorganisms to render them non-pathogenic or to the cells to prevent infection by the microorganisms.
The invention also encompasses a device for to be placed in the vault of the vagina which comprises a ring which surrounds the cervix and a membrane spanning the central aperture of the ring to prevent the direct contact of ejaculate with the cervical tissues. The device is impregnated or coated with lectins and releases them into the vaginal environment over a period of time.

Accordingly, it is an object of the invention to provide an improved method for prophylaxis against sexually transmitted diseases.

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A further object is to provide a method of contraception.
A further object is to provide a method for binding and immobilizing pathogenic microorganisms in the vagina.
A further object is to provide a device for delivering lectins to the vagina over a period of time.
A further object is to provide an intravaginal device that protects the tissues of the cervix from direct contact with ejaculate.
Oth~r objects of the invention will become apparent from the following detailed description when considered in conjunction ;~
with the drawings. ~`~

BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a top plan view of a lectin-delivery device according to the invention.
Figure 2 is a bottom view of the lectin-delivering device of ;~
Figure 1.
Figure 3 is a cross section of the lectin-delivering device of Figures 1 and 2, taken along the line 3-3.
Figure 4 is a top plan view of another embodiment of the lectin-delivering device of this invention.
Figure 5 is a bottom view of the lectin-delivering device of Figure 4.
Figure 6 is a cross section of the lectin-delivering device of Figures 4 and 5, taken along the line 6-6.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODI~ENTS
Lectins are carbohydrate-binding proteins of nonimmune origin that agglutinate cells or precipitate polysaccharides or glycoconjugates, i.e., proteins or lipids conjugated to oligo- or polysaccharides. They are widely distributed, and have been isolated from both plant and animal sources. Their reactions with living cells are based on their ability to bind with antibody-like specificity to particular arrangements of the sugar residues that make up oligo- or polysaccharides.
The surface of eucaryotic cells contain very numerous molecules of glycoproteins and glycolipids. Similarly, the cell walls of bacteria and the envelopes and capsids of viruses contain structural polysaccharides and/or glycoproteins. The carbohydrate moieties of these molecules which are displayed on the cell surfaces exhibit great variety in composition and structure that serves to distinguish the types of cells and to serve as a signal to other cells or materials which come into contact with the cell. For, example, variation in the carbohydrate moieties of glycoproteins in the membrane of red blood cells serves as the basis for the conventional blood typing classification. When lectins recognize and bind to certain çarbohydrate moieties they may serve to cross-link and agglutinate the cells bearing the binding groups, a property that earns for them the alternate name of agglutinins. Furthermore, because the same sort of carbohydrate moieties often serve as attachment points for pathogens to bind to target cells and ~1321.`3 ~
, .vade them, lectins may block infection of target cells by blocking the sites used by pathogens as recognition markers. The same type of specific binding occurs between sperm and egg in conception, and can be blocked by lectins. The binding ability of lectins may be very specific for certain mono- or oligosaccharides, allowing lectins to be used as a powerful tool for investigating the oligosaccharide epitopes on the surface of organisms or cells. Lectins can distinguish between blood cells of specific blood type, malignant from normal cells, and among species and genus of organisms. While glycoproteins, glycolipids, and bacterial cell walls are believed to be the main lectin-binding locations on the surface of cells, it is not excluded that carbohydrate moieties derived from other molecules or cellular structures may be displayed on the cell surface or that other lectin-binding structures may be present on cell surfaces. All such lectin-binding structures may be targets for the lectins used in the method of this invention. ~;
Current medical uses of lectins include distinguishing erythrocytes of different blood types (blood typing~. More recently, lectins have been used ex-vivo in depleting T cells of patients undergoing bone marrow transplantation.
Among the microorganisms that are bound by certain lectins are infectious organisms such as bacteria, protozoa, and viruses.
Lectins may be used to identify such microorganisms in vitro and are aiso capable of binding to them in vivo, thereby preventing them from infecting living cells. Human disease-causing 2 i~32~ ~

`~rganisms (and the diseases caused by them) that can be bound by lectins include Neisseria qonorrhoeae (gonorrhoea); Chlamvdia trachomatis (chlamydia, lymphogranuloma venereum); Treponema pallidum ~syphilis); Haemophilus ducrei (chancroid); Donovania qranulomatis (donovanosis); Mvcoplasma ~neumoniae, M. hominis, M.
aenitalium, Ureaplasma urealyticum (mycoplasmas); Shiaella flexneri (shigella); Salmonella tv~hi, S. choleraesuis, S.
enteritidis (salmonella) Campvlobacter fetus, C. ieiuni (campylobacter); human immunodeficiency virus HIV-1 and HIV-2 (HIV, AIDs); HTLV-l (T-lymphotrophic virus type l); herpes simplex virus type 1 and type 2 (HSV-l and HSV-2); Epstein-Barr virus; cytomegalovirus; human herpesvirus 6; varicella-zoster virus; human papillomaviruses (many types) (genital warts);
molluscum contagiosum (MSV); hepatitis A virus, hepatitis B virus (viral hepatitis); Trichomoniasis vaainalis (trichomoniasis);
yeasts such as Candida albicans (vulvovaginal candidiasis).
Other diseases that are transmitted by contact with bodily fluids may also be transmissible by sexual contact and are capable of ;
being prevented by administration of lectins according to this invention. Accordingly, the term sexually tran~mitted diseases (STD's) is to be interpreted in this application as including any disease that is capable of being transmitted in the course of sexual contact, whether or not the genital organs are the site of the resulting pathology.
Inasmuch as lectins are also capable of agglutinating human sperm and other components of the male ejaculate, and thereby _ 9 _ -, ~ ~r 21 1321~ ~

.andering the sperm immobile, intravaginal administration of lectins can also serve as a method of contraception.
According to the invention a dose of lectins adapted to bind and agglutinate pathogenic microorganisms and/or block the recognition sites on target cells is administered to the vagina prior to sexual intercourse. The active ingredients may also include lectins capable of binding and/or inactivating sperm to ~;
serve as a contraceptive.
Because of the specificity of lectins for certain microorganisms, it is preferred to administer a mixture of lectins chosen for their properties of agglutinating specific pathogens. It is also according to the invention to administer a mixture of sperm-agglutinating lectins and lectins capable of binding to pathogenic organisms to provide simultaneous contraception and protection against infection.
A representative listing of lectins, the abbreviations by which they are referred to, and their sources is given in Table 1.

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Tabl~ ectins ~nd Abbreviations Qç~n Soux~e A~nA Anguilla anguilla (Eel serum) AAurA Aleuria aurantia ~Orange peel fungus) ABA Agaricus bi~porus ~Mushroom) ABr~ Amphicarpanea brac~eata (hog-peanut) APA Abrus precatorius (Jequirity bean) BPA Bauhinia pu~purea alba ConA Concanaval~a ensi~or~is (Jack b~an) CSA Cytisus scoparius ~Scotch broom) DSA D~ura Stra~onium (Jimson weed, Thorn apple) ECA Erythrina crysta~all~ (Coral tree) ECorA Erythrina coralldendron (Coral tree) DBA Dolichos biflorus (horse gram) GNA Galanthus n~alis (Snowdrop b~lb~ :
: GSA-l/GSA-lI Griffonia simplieifol~a HAA Helix asp~rsa (Garden snail) a~ HPA Helix pomatla (Roman or edible snail) ~AC Artocarpus lnteg~i~olia (Jacal~n) , I , LAA I Laburnum alpinum LBA Phaæeolus lunatis (also limensis) ~Lima bean) LCA Lens culinaris ~lentil) 2 1 .~
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LEA Lycopersicon esculentum (Tomato) LOA Lathyrus oderatus (Sweet pea) :~
LTA Lotus tetxagonolobus (Asparagus pea) -MPA Maclura pomifera (osage orange) NPL Narcissus pseudonarcissus PAA Phytolacca americana (Pokeweed) PHA Phaseolis vulgaris (Red kidney bean) P~A Arachis hypogaea (Peanut) -~
PSA Pisum sativum (Pea) RCA-I/RCA-II Ricinus communis (Castor bean) SBA Glycine max (Soybean) SJA Sophora japonica (Japanese pagoda tree) :
STA Solanium tuberosum (Potato) TKA Trichosanthes kinlowii ;
UEA-I/UEA-Il Ulex europaeus (Gorse or Furz seeds) VAA Vi~cum album (European mistletoe) ~
VFA Vicia faba (Fava bean) ~.
VGA Vicia graminea VSA Vicia Sativa W A Vicia villosa (Hairy vetch) ;
WFA Wisteria floribunda (Japanese wisteria) WGA Triticum vulgaris (Wheat germ) Quc-WGA . Succinyl WGA ;:~

~ ~ 3~ ~ 8 For exAmple, N. qonorrheae is agglutinated by lectins that ~ind to N-aoekyl-~-glucosamine residue~ on their surfaces. Such lectins include wGA and STA, which are known ~o agglutinate all 193 clinical isolates of N. qon~rrheae. WGA is ef~ecti~e or such agglutination at a concentration o~ 3.1 micrograms per milliliter. Oth~r lectins showing some agglu~in~ion activity with respect to N. qonorrh~Q include RCA-I, R Q -II, GSA-I, and SBA.
~ortain speci~s Or Chlam~dia (~shs~ , B3i~5L~ and ~neumonia~) ar~ Xnown to be bound ~y the lectins ConA, DBA, VEA-l, SBA, and PNA. WGA also binds to the receptors on certain cells, ther~by ~locking in~ection by C. ~r~chomatis and .
C. ~ taci.
P~A binds to several isolates of ~L_9YÇ~L, suggesting that N-acetyl-D-glucos~mine i~ present in the cell envelop~
polysaccharide. ~' WGA has been ~ound to ag~lutina~e ~ variety o~ bac~erial ~ells, including E~cherichia co~l, Micr~coccus luteus, and some typeg o~ D~o~ y~ ~ - WGA, gpecific for N-acetyl-D-glucosamine and SBA, speci~i~ for N-acetyl-D-galactosamine, are chpAble o~ agglutinating the ~any bacterial species which contain thes~ sugar re~idues in their call wall polysaccharides.
Va~ious lecti~s are capablo of binding to certain glyooproteins present in th~ coat o~ HIV viru~. ~or example, ConA ~as baen found to ~loek inf~ction o~ certain cell lines :.
against inf~ction by ~IV in vitro, and conglutinin, a lectin 3 rJ ~

derived fro~ ~ovine serum, has been found to bind to the ~IV
envelope precurso~ protein gp 160, thereby preventing attach~ent to CD-4 receptors o~ target cells in vi~ro. G~A has been found to prevent infeetion of T-cells by HIV in vi:~. ronsequentlY, 5 Ccn~, GNA and WGA have been ~ou~d to be effective at prevanting infection of target cells by HIV-1 and HIV-2 in vitro. NP~ and conglutin~n ~ave shown some activity as well.
RPA and ConA have de~onstrated e~ficacy ~n the prevention of in~ection of target cells by HSV-1 and HSV-2.
Loctins are also use~ul in ag~regation of sperm. P~A, WGA, S~, ConA, PSA, APA, ECA, ECorA have demonstrated varying degrees o~ e~icacy in agglutinatio~ o~ sperm. .
While the l~ctins discussed above and the organis~s agains~
which they are ~ffective are representativ~ of ~se~ul lectins ~
accord~ng to the invention, it is to ba understood that o~her .:
lsctins may be di~covered which are active in the binding and agglutination of the pathogens of sex~ally transmitted dis~ases, ~nd that the use of ~uch lectin~ i~ intended t~ be in~luded within t~e 8COp~ 0~ the ~nvention.
2~ ~n determinlng the amoun~ of lectin to be administered ~or e~ective binding andJor aggiutination of the pathogenic organismC o~ STD~s, the amount o~ lectin tha~ mlght ~ bound to vag$nal tissUes and thQre~y ~ade u~available ~or agglu~ination of p~thogens mu~t b~ considered. In studies ~n mur$ne vaginal 2S tissue, DBA, LAA, ~BA, ~CA, L~A, RCA-I, RCA-II, S~A, STA, VGA, WFA have ~een ~ound not to bind to t~e tissue at any stage o~ the 2~3~1~
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estrus cycle. ~n contrast, ABA, MPA, PHA-E, PHA-L, Suc ConA, and WGA bound strongly to vaginal tissues at all stages of the estrus cycle. CSA, GSA-I, GSA-II, HAA, HPA, JAC, PNA, PAA, SBA, Suc WGA, UEA-I, VFA, and W ~ exhibited in~ermedia~ ~egrees o~
5 bi~ding to murine vaginal tissues. The amount o~ lectin to be administered ~or e~ective prophylaxis can be deter~ined from the r~lative binding ~ffect of the various lectins to the pathogen and to th2 ~aginal tissu~s.
The s~lection o~ part~cular lectins to be administere~ will depend on the diseases sought to be prevented. It is preferred to administer a mixture o~ lectins, each s~lec~ed for ~est agglutinativ~ efficacy against a particular pathoge~.
~ he lectins may be ad~inistered in any ~luid or ointment ~ehicle su$table for topical administration of ~harmaceutical compounds, Thus creams, ointments, suppositories, ovules and the lik~ may be ~ormulated in which the selected lectins a~e dispersed in a non-toxic vehicle suita~le ~or topical and in particular ~or vaginal administration. Such vehicles include wh~te petr~latum, hydrophilic petrol~tum, lanolin emulsions, pol~ethylene glycols, cocoa butter and the li~e. According to the ~nvent~on the dispers~o~, suspension, or ~olution of lectins in the ve~icle may bo appl~ed to the site o~ a le~ion on t~e external genitalia, such as the lesions produced ~y herpe3e '~ simplex virus typ~ l or type 2, chancroi~, genital warts, chancre o~ syphilis, and th~ liX~, to prevent the transfer of pathogens.
~he lectins may al50 b~ in~roduced into the v~gina in order to ~ ~ 1 3 r I 1 ~

prevent concep~ion or in~ection by pathogens introduced during sexual intercourse. ~he amount ~ lectins to be ~pplied will be an amount that is ef~ective to preven~ conception or infection or substantially reduce the risk thereo~. The amounts n~ed~d to achieve th~se goals will d~pend on the e~fectiveness of the indlvidu~l lec~insj ~heir a~finity ~or the target cell and t~e :~
li~e. The e~2cti~e amounts can be determined ~y the skilled :~.
practitioner by rou~$ne experimentation.
Because some of the conventional means o~ administering lo m~dications to the vagin~ have certain drawbaoks, as discussed above, it i9 pre~erred to incorporate the lectins into a device which will remain in ~h~ vagina and dispense the lectins over a prolonged period o~ time in order to ~aintain an e~ective concsnt~atlon of ~he lect~ns in the vaglna. S~ch a de~ice may also be design~d to provide a barrier ~hat will prevent the acces~ of patho~enic organisms into the uterus and may also function as a contracept~ve device.
The dev$ce o~ the inventio~ is genexally a ring o~
ell~ptical or circular cross-fiection ~ade, e.g., ~ro~ a biocompatibl~, nontoxic thermoplasti~ poly~er or polymeric open-cell polyu~ethane. Bond~d to one side o~ the ring or ~olded integral ~ith it is a web o~ the sa~e material.
A d~vice according ~o t~e invention having a ring or elliptical cross-section is illustrated in Figures 1-3, wherein 23 the reference numerals indicate the same elements in aach ~igur~.
A ring 102 of generally ~lliptical c~oss sectio~ consti~utes ~he 39~

nldin structural member of the devic~ and is sized to fit com~Eortab-y in the vaginal vaul~ surrounding the c:e~vix. To one ~ de of t~e r~ng 102 is ~astened a relatively thin web 104, p~eferably ~ade of the same ~a~erial as the ring. ~n ~ome 5 enbodi~ents the web ~nay be molded i~egrally wi~h the ring.
~ igures 4-~ ~llustrate anot:her embodimen~ of the invention wherein a ring 202, o~ g~ne~ally circ:ular cross E~s~ction, carries a thin web 2 04 spanning the central apertur~ on one side of the ring .
Th~ device may be manu~actu~ed from. any ~aterial that has been shown to be biocompatible with the envi~omnent o~ the vagina and to be capable of holding lectins wi~hin its bulk and rele~sing the~ slowly to the surrounding environment. Several materials suitable ~or this function are already known from the Vaginal devices already ln use or disclosed in the technical literature. Conse~uently, the s~illed practitioner can easily sel~ct a suitable material ~rom which to ma~e the device of this invention. The lectins may also be incorporated into a thin ~lexible coating, placed on the ring or web or both, and desig~ed to rel~ase the lact~ns there~ro~ over a pe~iod o~ ti~e, e.g., by di~usion out of the coating o~ by gradual ~rosion and dissolution of the coating in th~ vaginal environment.
The device o~ th~ inve~tion is designed to deliver one or ~ore lectins locally in the vagina ~or:
1) contrac~ption, by binding to the glycoproteins, glycolipids an~ other glycocon~ugates on the sur~acs o$ sperm and 2 ~ ~

by binding to the glycoproteins, glycolipids, and other glycoconjugates in the -~eminal fluid, thereby creating an ejaculate with significantly greater vi8cosity, and thereby p~eventing sper~ ~rom ~xiting the e;aculate;
2) prophylaxis a~ainst various sexually tran~mitted diseac~s by binding to the glycoproteins, glycolipids, and other glycoconjugates on the sur~ace of ~he bacterial agent or viral coat of the virus and the glycoproteins, ~lycolipids, and o~her glycocon~ugates in the seminal fluid thereby prev~nting the in~ect~ OU5 agent from reachin~ the target tissu~: and 3) prophylaxis agalnst various sexually transmitted diseases by binding to the glycoprote1ns~ glycolipids and other glycoconjugate recQptor sites on the vaginal strati~ie~ squ~mous epithelium and cervical columnar epithelium, whereby the reoogn~t$on sites ~or ~ttack by pathogens are blocked or conceal~d.
The devi~e o~ the invention also operates by providing a physlcal barrier to the direct deposition of ejaculate on the cerv~x. This design assures that the concentration of p~otective lectins in the cervical region will not be diluted and ove~whelmed by the e~aculate. Rather, tha sperm and the pathogens p~esent in the ejaculate can only rea~h the cervlcal region gradually by diffusion and tran~port around the outside of the peri~hesal ring o~ the device. This slow transport o~ the 2~ sperm ~nd pathoqons ~rom th- ~a~ulate to ~h~ cervical region assures that the le~tins will have an opportunity to b$nd to all ` ` 2 1 ~ 3 appropriate c~nstit~ents of the ejac~late. The presence o~ the lactins, which Will coagulate and inhibit the transport ~f sperm and pathogens, makes it unnecessary to have a device ~hat fits ti~htly ~ither around the cervix or again~t the wall of the vagina.
Accordingly, ~he device of the invention has several advantages over the va~ih~l ~edication and ccnt~aceptive d~vices currently a~ailable: ;
1) lt is ea~ily inserted and comfor~able to use.
2) Because of its position in the top of the vaginal canal, it ensures that the lectins are carried down through the v~gi~a.
3) Si~ce it i5 placed next to the cervix it can also deliver l-ctins targe~ed to the cervix.

4) Gradual rei~ase of 14ctins provides a ~ore consistent delivery over time, thus ensuring more efficient trea~ment.

The inv~ntion having now b~n fully describQd, it should be und~rstood th~t it may be em~oaied in other ~peciric ~rms or var$ations Without departing from its spirit o~ essential characteristics. Accordingly, the embodimentq described above ar~ to be con~ider~a ~n all res~ec~s as illustrative and not restrictive, the scope o~ the invention ~ein~ indicated by the append~d claims rather than by ~he ~oregoing de w ription, and all changes which come within the ~eaning and range o~ equ$valency o~
2g the claims are intended to be embraced therein.

Claims (10)

1. A method of preventing the transmission of sexually transmitted diseases comprising administering to the vagina an amount of a composition containing at least one lectin capable of binding to a pathogenic microorganism effective to diminish the infactive capability of said microorganism, said lectin being dispersed in a biocompatible non-toxic vehicle.

2. The method of Claim 1 wherein a plurality of lectins are administered.

3. A method of contraception comprising administering to the vagina an amount of a composition containing at least one lectin capable of agglutinating sperm or other components of male ejaculate sufficient to render said sperm incapable of fertilization, said lectin being dispersed in a biocompatible non-toxic vehicle.

4. The method of Claim 3 wherein a plurality of lectins are administered.

5. A vaginal medicator comprising a ring of a flexible resilient material having a central aperture and spanning said central aperture a web of flexible resilient material, at least one of said ring and said web being impregnated with a lectin and being capable of releasing said lectin to a surrounding vaginal environment.

6. The medicator of Claim 5 wherein said flexible resilient material is impregnated with a plurality of lectins.

7. A vaginal medicator comprising a ring of a flexible resilient material having a central aperture and spanning said central aperture a web of flexible resilient material, at least one of said ring and said web being coated with a composition comprising a lectin and a binder therefor, said composition being capable of releasing said lectin to a surrounding vaginal environment.

8. The medicator of Claim 7 wherein said coating composition contains a plurality of lectins.

9. The use topically of at least one lectin capable of binding to a pathogenic microorganism effective to diminish the infective capability of said microorganism, to prevent the transmission of sexually transmitted diseases.

10. The use topically of at least one lectin capable of agglutinating sperm or other components of male ejaculate sufficient to render said sperm incapable of fertilization, for contraception.