Male anti-fertility agents

Abstract

Methods and compositions for inhibiting or preventing spermatogenesis in a male mammal. Also disclosed are compounds and formulations for use in such methods.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 10 / 304,665, filed Nov. 25, 2002, which is a continuation of U.S. application Ser. No. 09 / 591,253, filed on Jun. 9, 2000, now U.S. Pat. No. 6,521,641, which is a continuation-in-part of U.S. application Ser. No. 09 / 405,748, filed Sep. 27, 1999, now abandoned, which claims the benefit of Provisional Application No. 60 / 103,507, filed Apr. 14, 1998. [0002] The entire teachings of the above application(s) are incorporated herein by reference.FIELD OF THE INVENTION [0003] The present invention concerns methods and compositions for inhibiting or blocking fertility in a male mammal by the administration of a retinoid or retinoid derivative that is able to act as an antagonist or inverse agonist of a retinoic acid receptor (RAR). The effect is reversible upon cessation of treatment with the RAR antagonist or inverse agonist. BACKGROUND OF THE INVENTION [0004] The prevention of unplanned pregnancy in h...

AI Technical Summary

Benefits of technology

[0021] It has been known for some time that among the various results of a severe vitamin A (retinol) deficiency in mammals is sterility and blindness. See Eskild W. & Hansson. V., Vitamin A Functions in the Reproductive Organs in Vitamin A in Health and Disease 531 (Blomhoff, R. ed., 1994) (hereinafter Eskild). A complete deficiency in retinoids is fatal. Administration of retinoic acid in the absence of retinol can alleviate many of the symptoms of vitamin A deficiency, giving rise to blind and sterile animals that remain otherwise healthy.

Problems solved by technology

However, in recent years questions have arisen about the health risks involved in continued long term use of contraceptive hormones.

There have been reports of increased risk of certain forms of cancer, such as breast and cervical cancer, though the use of the Pill.

Surgical sterilization, whether through tubal ligation or vasectomy, is nearly 100% effective, but is only sometimes reversible.

Condoms, made of either synthetic polymer materials or animal skin, are less effective than birth control pills and their effectiveness is further subject to subversion through the possibility that small breaks may be present, permitting leakage of semen.

Additionally, the use of a condom requires the affirmative action of the male, usually immediately prior to the initiation of sexual intercourse and some men report a loss of sensation through the use of condoms.

Hence, subject non-compliance is also an issue in the use of condoms.

Side effects may be similar to those involved in the use of birth control pills, and include a risk of developing ovarian cysts.

Additionally, while the implant can be removed, the procedure is difficult even for skilled surgeons due to the formation of scar tissue around the implant.

Depending on the design, the devices appear to interfere with sperm motility or the implantation of the fertilized egg in the uterine wall.

Side effects can include cramps, backache, spotting, or heavy periods, and women may have an increased risk of ectopic pregnancy or infertility.

IUDs are usually not recommended for women who have not had children or who think they will have children in the future due to these latter risks.

The user can insert them as long as a number of hours before sexual intercourse, and the effects are temporary; if pregnancy is subsequently desired, the woman can discontinue their use with a concomitant return of fertility.

As mentioned above, the former of these methods is irreversible and the latter is neither inherently as effective as other methods, nor is compliance as high.

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