WO1991004042A1

WO1991004042A1 - Method for inducing vaginal lubrication

Info

Publication number: WO1991004042A1
Application number: PCT/US1990/005281
Authority: WO
Inventors: Jan Fahrenkrug; Bent Ottesen
Original assignee: Senetek, Plc
Priority date: 1989-09-18
Filing date: 1990-09-17
Publication date: 1991-04-04
Also published as: AU6522590A

Abstract

Vaginal lubrication is induced in a human female by administration of the human neuropeptide, peptide N-terminal histidine C-terminal methionineamide.

Description

METHOD FOR INDUCING VAGINAL LUBRICATION

TECHNICAL FIELD

The present invention relates to the 27-amino acid, human neuropeptide, peptide N-terminal histidine C-terminal methionineamide. More particularly, the invention concerns the induction of vaginal lubrication by administration of the neuropeptide.

BACKGROUND OF THE INVENTION Peptide N-terminal histidine C-terminal methionineamide, hereinafter referred to as "PHM", is a 27-amino acid, carboxy-terminal-amidated neuropeptide of humans. The amino acid sequence of PHM is known. Itoh et al. Nature 304, 547 - 549 (1983). PHM is the human analog of the 27-amino acid, carboxy-terminal-amidated, porcine neuropeptide, peptide N-terminal histidine C-terminal isoleucineamide, hereinafter referred to as "PHI". Tatemoto and Mutt, Proc. Natl. Acad. Sci. (USA) 78, 6603 - 6607 (1981); Itoh et al., supra. The sequences of PHM and PHI differ at only position 12, where PHM has lysine and PHI arginine, and position 27, where PHM has methionineamide and PHI has isoleucineamide.

The sequence of PHM occurs in the 170-amino acid polypeptide, prepro-vasoactive intestinal peptide. This 170-amino acid polypeptide is the precursor from which the neuropeptide, hr vasoactive intestinal peptide, hereinafter referrec as "VIP", is made in vivo by post-translational j._^^essing. Itoh et al., supra. VIP is a 28-amino acid, carboxy-termina -amidated polypeptide which has 50 % sequence homology to PHM and sequence homology to a number of other biologically active polypeptides. Both VIP and PHM are members of the secretin-glucagon family of peptide hormones. From the structure of the 170-amino acid, prepro-VIP, and assuming that in vivo PHM were made from the precursor simultaneously with VIP and were not degraded by mechanisms that differed from those that degrade VIP, a 1:1 molar ratio of VIP and PHM would be expected in tissue. It appears, however, that there are tissue- or cell-specific differences in the processing of the VIP precursor or in the mechanisms by which VIP and PHM are degraded, because one of VIP or PHM is present to the exclusion of the other in some tissues and, in many tissues where both are present, they are present in non-equimolar concentrations. See Fahrenkrug, Peptides 6, 357-361 (1985); Fahrenkrug et al., Regul. Peptid. 12, 21-34 (1985). Hokfelt et al., Acta Physiol. Scand. 116, 469-471 (1982).

PHM shares some of the biological activities of VIP; but, in most cases in which both peptides have the same activity, PHM has lower potency than VIP. Hoist et al., Am. J. Physiol. 252, G182-189 (1987); Bardrum et al., Am. J. Physiol. 251, E48-51 (1986); Christofides et al. (I), Peptides 5, 261-266 (1984); Christofides et al. (II), Endocrinology 115, 1958-1963 (1984); Lundberg et al., Peptides 5, 593-606 (1984); Lundberg and Tatemoto, Eur. J. Pharmacol. 83, 143-146 (1982); Bataille et al., FEBS Lett. 114, 240-242 (1980).

Administration of VIP to a human female is known to induce vaginal lubrication. Ottesen et al., Peptides 8, 797-800 (1987); PCT International Publication

No. 88/03928. Hypotension, increased pulse rate, and flushing of the skin of the face and trunk are disadvan¬ tageous side effects that have been encountered in females in whom vaginal lubrication has been induced by administration of VIP.

Although PHM occurs in the female genital tract, its physiological function or functions in the various organs there, including the vagina, have remained unclear. Insufficient vaginal lubricatory activity (i.e., secretion of fluids from the vaginal wall into the vaginal cavity resulting in vaginal lubrication) is a problem for many females, particularly post-menopausal females and those suffering from certain diseases, such as diabetes, which involve atherosclerosis or neuropathy. One consequence of insufficient vaginal lubrica- tory activity is increased susceptibility to various dis¬ eases of the female genital tract.

Vaginal lubrication normally occurs during sex- ual arousal, and insufficient vaginal lubricatory activi¬ ty can result in pain during sexual intercourse and gen¬ erally unsatisfactory sexual relations.

SUMMARY OF THE INVENTION we have now discovered that administration of

PHM to a female, either systemically as by intravenous injection, or locally to the vaginal wall, induces vaginal lubricatory activity and associated vaginal lubrication. Advantageously and unexpectedly, the pharmaco¬ logical effect of PHM in causing vaginal lubrication persists for a significantly longer time than that of VIP, when the PHM and VIP are used at dosages that cause vaginal lubrication at about the same rates and, concomitantly, side-effects (e.g., lowering of blood pressure, increase in pulse rate) to about the same extents. Thus, PHM can be used at a dosage that causes vaginal lubrication to the same extent as VIP, at a vaginal-lubricatory-effective dosage, but that causes side-effects to a lesser extent than the VIP at such VIP dosage.

The present invention thus provides advantageous methods for protecting against bacterial, fungal and other infections of the genital tract of a female associated with insufficient vaginal lubricatory activity. The invention further provides advantageous met_hods for increasing vaginal lubrication in a female during sexual arousal and intercourse. For a female who suffers from insufficient vaginal lubricatory activity during sexual arousal or intercourse, application of the methods of the invention to increase vaginal lubrication during sexual arousal or intercourse results in reduction of pain during intercourse and, associated therewith, generally improved sexual relations.

DETAILED DESCRIPTION OF THE INVENTION

The present invention entails a method for inducing vaginal lubricatory activity in a human female, which comprises administering to said female an amount of PHM effective to induce vaginal lubricatory activity.

The invention entails also compositions for carrying out the method of the invention.

The PHM for use in the method of the present invention is, as indicated above, a known, human neuro¬ peptide and is readily available in highly purified form from numerous sources.

Administration of the PHM in accordance with the method of the invention can be systemic or local. Systemic administration is preferably by intra¬ venous injection, although intraperitoneal, intramuscular or subcutaneous injection can also be employed. Continu¬ ous infusion may be used.

Local administration is preferably to a portion of the wall of the female genital tract, most preferably to a portion of the inner wall of the vagina (i.e., the wall which defines the vaginal cavity) . Local adminis¬ tration can be accomplished by release of PHM by diffu¬ sion from a solution dispersed in a suitable support, such as a porous tampon or a suppository made with a composition comprising oleaginous base materials, or a suitable composition, such as an emulsion, cream, jelly, or tablet, placed in the vaginal cavity and in contact with the inner wall thereof. Upon contact of the dif- fusing PHM with the vaginal wall, it is absorbed thereby and taken up by cells therein, whereupon its vaginal lub¬ ricatory activity is effected. Alternatively, local ad¬ ministration can be by deposit of a volume of between about 1 ml and about 10 ml of a PHM-containing solution into the vaginal cavity in a manner whereby at least a portion of the vaginal wall is contacted with the solu¬ tion. One convenient means for local administration of PHM in accordance with the invention is application of a volume of solution into the vagina using an applicator such as one used to self-administer contraceptive foam. Subepithelial injection of a PHM-containing solution (typically between about 0.1 ml and 1 ml) at the inner wall of the vagina is also encompassed within local ad¬ ministration of the PHM. In accordance with the invention, the PHM will be administered as part of a physiologically acceptable composition. Such a composition, especially suitable for systemic administration or local administration involving subepithelial injection, can be a solution comprising the PHM dissolved in a physiologically acceptable medium, such as physiological saline or phosphate-buffered saline, which may optionally include other physiological¬ ly acceptable substances, such as human serum albumin or the like, at physiologically acceptable concentrations, as understood in the art.

Compositions more suitable for local administra¬ tion (other than by subepithelial injection) can also be formulated by the skilled in the art. See, e. g. , Okada et al., J. Pharmaceut. Sci. 71, 1367 - 1371 (1982) and 72, 75 - 78 (1983). Such compositions include those com¬ prising, optionally dispersed in a suppository or cream of physiologically acceptable oleaginous substances (e.g., WITEPSOL-S55™ sold by Dynamit Nobel AG, W. Germany) or a jelly of starch, carrageenan, xanthan gum, locust bean gum or the like, the PHM in an aqueous solution that is approximately isotonic with physiologi¬ cal saline, has a pH of about 2.5 to about 4.5, and com¬ prises human serum albumin or the like (preferably pepti- dase free) at about 0.01 - 1.0 %, a protease inhibitor such as aprotinin (e.g., sold as Trasylol™ by Bayer

A. G., Leverkusen, W. Germany) at 0 - 100 U/ml, NaCl at about 0.9 %, and a polybasic acid, such as citric, succinic or the disodium or dipotassium salt of edetic, at 0.2 M to 0.5 M. The concentration of the PHM in the physiologi¬ cally acceptable solution will be between about 1 μg and about 1 mg per ml. As the skilled will understand, the concentration will depend on the route of administration (e.g., local or intravenous), the total dose to be administered, and the time period over which the administration is to occur.

A solution is prepared by simply dissolving under sterile conditions the purified, sterile PHM, to the desired concentration in sterilized, physiological acceptable medium. Then, if the solution is to be dis¬ persed in a tampon, suppository, cream, jelly or the like to make a composition for local administration, the solu¬ tion is combined with the desired substance, also under sterile conditions. The solution or other composition can be prepared at any time prior to use, including imme¬ diately prior thereto. If prepared more than a few hours prior to use, the solution may include physiologically acceptable, non-irritant preservatives, such as about 0.1% benzalkonium chloride. Similarly, the solution, or composition for local application, if prepared more than a few hours prior to use, is preferably maintained at low temperature, preferably about 0 "C to about 4 *C. The dosage of PHM to be administered, and the rate of administration, will depend on the age, weight, and medical condition of the female to whom the neuro- peptide is being administered, the route of administra¬ tion, and the purpose of the administration.

For purposes of inducing vaginal lubrication during sexual relations, a single intravenous injection of about 10 μg to about 1 mg (about 0.1 μg/kg body weight to about 10 μg/kg body weight) of PHM in 1 ml to 10 ml of solution may be administered between about 10 minutes and 1 minute prior to intercourse or a volume of between about 1 ml and 10 ml of solution, or solution-containing composition, with between about 10 μg and 10 mg of PHM may be delivered into the vaginal cavity, to bathe the inner vaginal wall, between about 10 minutes and about 1 minute prior to intercourse.

For purposes of inducing vaginal lubrication to prevent, or reduce the risk of contracting, infections of the genital tract in a female WΪ.D suffers from inadequate vaginal lubricatory activity, a continuous mode of admi¬ nistration may be employed. Suitable continuous modes of administration include continuous intravenous administra¬ tion; percutaneous administration, as from a skin patch perfused with PHM in a physiologically acceptable carrier and applied to a body part suitable for absorption from the patch into the blood stream; or vaginal administra¬ tion, as from a tampon or suppository perfused with a PHM solution and inserted into the vaginal cavity. Depending on the age, weight, and medical condition of the female, including the severity of the impairment of vaginal lubricatory activity and the nature of the infection or infections to be protected against, the rate of adminis¬ tration will be between about 10 gram and 10~^"4 gram per kilogram body weight per hour over periods ranging from about 10 minutes to about 24 hours, interspersed with periods during which no PHM is administered. It is intended that PHM be administered in accordance with the invention under the guidance of a physician. For a particular female, the dosage, route and rate of administration of the PHM will be determined by the physician, taking into account the above-described factors (age, weight, degree of impairment (if any) of vaginal lubricatory activity, medical condition, and purpose for administration of the PHM) . The invention will now be illustrated in the following example.

EXAMPLE The effect of administration of PHM sub- epithelially to the inner wall of the vagina was studied as follows with 6 human volunteers.

The volunteers ranged in age from 20 - 35 years, weighed 52 - 62 kg, had had 0 - 3 pregnancies and 0 - 2 deliveries, and were receiving no medication, including oral contraceptives and intrauterine devices. With each volunteer, the experiment was performed between the seventh and sixteeenth day of the menstrual cycle.

The volunteers had given written, informed consent after the study was approved by the local ethical committee of Copenhagen, Denmark.

The volunteers were lying on their backs during the experiments.

The experiments were carried out on two different days with each volunteer, one day with control and human VIP and another day with control and PHM.

Blood pressure, pulse rate and flushing of the skin of the face and trunk were monitored throughout the experiments with each volunteer.

Following Ottesen et al., Eur. J. Clin. Invest. 13, 321 - 324 (1983), a measuring electrode was posi¬ tioned on the front wall of the vagina, about 5 cm up, to measure change in blood flow to the vagina. As disclosed in Ottesen et al., Peptides 8, 797-800 (1987) and PCT International Publication No. 88/03928, in connection with VIP, vaginal blood flow as measured with the measur¬ ing electrode is correlated to vaginal lubricatory acti¬ vity, with increasing blood flow associated with increas¬ ing rate of exudation of fluid at the inner wall of the vagina due to vaginal lubricatory activity. There is no reason to believe that the correlation between vaginal blood flow and rate of vaginal lubrication observed with administration of VIP does not apply as well to adminis¬ tration of PHM. Power consumption at the electrode was measured throughou* ich experiment. As contro^* .2 ml of sterilized physiological saline, warmed to 37 ^βC, was injected subepithelially at a depth of 2 mm at a site on the front wall of the vagina, about 3 cm up. 30 minutes after the injection of the saline solution, 0.2 ml of sterilized physiological saline containing a first amount of filter-sterilized PHM

(on one of the days) or filter-sterilized human VIP (on the other of the days), also warmed to 37 "C, ^•"'is inject¬ ed subepithelially at a depth of 2 mm at abou he same site as the injection of the saline without n_^- opep- tide. Again, at intervals of 30 minutes, a second and third amount of PHM (on one of the days) or human VIP (on the other of the days) were administered in the same way as the first amount. Power consumption was recorded until 1 hour after administration of the third amount of neuropeptide. The first, second and third amounts of PHM were 1 μg, 10 μg and 100 μg, respectively. The first, second and third amounts of human VIP were 0.1 μg, 1.0 μg and 10.0 μg, respectively. The results obtained, including the maximum power consumption observed after each administration of control or PHM (or VIP) solution, are listed in Table I. Table I

Neuro- Quantity Injected Maximum Increase Side peptide in 0.2 ml Saline in Power Consumption Effects

(μg) W

(mean ± 1 s.d. )^

Control²-/ 0 2 ± 0.5 None

PHM 1 2.5 ± 1 None

PHM 10 6 ± 2 None

PHM 100 11 ± 1.5 None

End (PHM)³-/ 5 ± 3 None

Control^/

VIP 0.1 VIP 1.0 VIP 10.0 End (VIP) 3/

1/ If range is listed, mean and range are provided.

2/ Prior to tests with PHM.

3_/ One hour after final injection with neuropeptide.

4/ Prior to tests with human VIP.

5/ Increase in pulse from 61 ± 1.5 to 79 ± 2.6/min; flush¬ ing of face and trunk observed with 5 of the 6 women; no significant change in blood pressure.

With 100 μg PHM, the increase in power consumption began about 1 minute after the injection, reached a maximum about 2 minutes later, and decreased slowly to slightly less than half maximum after an hour. With 10 μg human VIP, the increase in power consumption began at about 1 minute after the injection, reached a maximum at 1 - 4 minutes later, and returned to zero at 13 ± 2.7 minutes after injection of the VIP solution.

None of the women experienced sexual arousal at any time during the experiments.

An increase in power consumption of 10 mW represents induction of vaginal lubrication to a significant level, as it corresponds to an increase of about 2-fold to about 3-fold over control levels (i.e., and sexual arousal) in the rate of exudation of fluid from the inner wall of the vagina.

Although it appears from the results listed above that side effects with administration of PHM to induce vaginal lubrication are significantly less than those with administration of human VIP, further experi¬ ments have shown that, at comparable dosages, PHM and VIP have about the same side effects. In this context, "comparable dosages" are those at which the vaginal blood flow increases (and rates of vaginal lubrication) caused by the two peptides are about the same.

Also it appears that, although PHM is somewhat less potent than VIP (about 3-fold to about 10-fold) in inducing vaginal lubricatory activity, PHM is advanta¬ geously effective in such activity over a much longer period of time than VIP. This conclusion is supported both by the experiment reported in this Example and other experiments. The results, relating to dosage, rate of vaginal lubrication and duration of vaginal lubricatory activity, of the other experiments were substantially the same as the results of the experiment reported in this example.

Although the invention has been described with some specificity, the skilled will recognize variations and modifications within the spirit and scope of the invention. Such variations and modifications are also intended to be within the scope of the invention as described and claimed herein.

Claims

WHAT IS CLAIMED IS:

1. A method of inducing vaginal lubrication in a human female which comprises administering to the female a vaginal lubricatory activity-inducing-effective amount of PHM in a physiologically acceptable solution.

2. A method according to Claim 1 wherein the PHM solution is administered locally to the inner wall of the vagina.

3. A method according to Claim 1 wherein the

PHM solution is administered systemically.

4. A method according to Claim 2 wherein a volume of between 0.1 ml and 10 ml of solution, containing between 10 μg and 10 mg of the PHM, is administered.

5. A method according to Claim 3 wherein the route of administration is intravenous.

6. A method according to Claim 5 wherein between 1 ml and 10 ml of fluid, containing between 10 μg and 1 mg of PHM, is administered in a single injection.

7. A method according to Claim 5 wherein the administration is by continuous infusion over a period of 10 minutes to 24 hours at the rate of 10~⁶ gram to

10~⁴ gram PHM per kilogram body weight of the female per hour.