Hormone replacement, Men's Health, General, Women's Health, Infant and Children | February 28, 2015 | Author: The Super Pharmacist
Condoms have been around in one form or another for centuries. We have had oral contraception for over half a century and intrauterine devices have been along for almost as long. Both women and men can undergo surgery as a means of permanent contraception (though technically reversible); however, most sexually active individuals are interested in short term, reversible forms of contraception. Are there any new contraceptive methods? What will contraception look like the early 21st-century?
There are certainly many more contraceptive options for female use than for male use. Women have oral contraceptive pills, injectable hormone contraceptives, intrauterine devices, intravaginal barrier protection (i.e. diaphragms), the “morning after” pill, and patches and rings containing contraceptive hormones. While no form of contraception is 100% successful, many of these forms come quite close when they are used properly. Nevertheless, not all of these approaches are safe or appropriate for all women. For example, women who smoke place themselves at increased risk of blood clots and heart attacks if they also take hormonal contraception. Likewise, intrauterine devices may increase the risk of ectopic pregnancies, infection, or other complications. Thus, the search for more convenient, more effective, and less risky contraception for women continues.
Perhaps unfortunately, one of the most rigorous areas of study among female contraception researchers involves revisiting an old method, namely - spermicide. Products with names such as BufferGel and C31G work by killing sperm in the vagina before they can fertilize an egg. The spermicidal agents are less effective than oral contraceptive pills, though C31G was more effective at preventing pregnancy than the commonly used spermicidal agent, nonoxynol-9. Spermicidal agents are most effective when combined with other forms of contraception.
The most well-known form of on-demand contraception is the “morning-after pill” or Plan B. It is a form of emergency contraception taken within 1 to 2 days after unprotected sex. There are several other forms of contraception taken before or after sexual intercourse that are either available or under development. The "morning-after pill" is simply a higher dose of levonorgestrel, a hormone that interferes with fertilisation. Other forms of the morning-after pill may also contain oestrogens, such as oestradiol. Mifepristone is a form of emergency contraception that is not technically a hormone, but rather blocks the effects of progestin, which is a hormone. Mifepristone is also known by the name RU-486 and is the highest rate of success among emergency contraceptive pills. a similar medication called gestrinone is equally effective as mifepristone in preventing pregnancy when used after sexual intercourse. Because this pill has been considered an “abortion drug”, as it can be used after confirmed pregnancy, it has faced political and regulatory hurdles in many Western countries.
Women who have infrequent intercourse may not need continuous contraception, such as would be offered by contraceptive pills. For women who simply need a form of contraception that can be used after occasional sexual intercourse, vaginal gels that disrupt ovulation are under development. Similar gels that interfere with sperms' ability to travel to the egg are also being investigated.
Contraceptive microchips are new way to develop an old contraceptive. A company called MicroCHIPS is developing a contraceptive microchip that is placed under the skin. It releases a dose of the hormone contraceptive, levonorgestrel, which enters the bloodstream and works to prevent pregnancy.
According to the developers, the contraceptive microchip can hold enough hormone contraceptive to deliver a dose every day for 16 years. The company completed a human clinical trial using the drug for osteoporosis, but they are confident that the same device can be used to provide any drug, including a contraceptive. Perhaps most impressively, is that the device is wirelessly controlled, which means that microchip can be told whether to release a dose of the drug or not. Therefore, the microchip could be used as reversible contraception controlled from a desktop or smartphone.
Since hormonal contraceptives can cause a number of unwanted side effects, ongoing research has focused on non-hormonal agents to prevent pregnancy. COX-2 inhibitors, better known as anti-inflammatory analgesics for conditions such as arthritis, appeared interfere with ovulation. In fact, one COX-2 inhibitor called meloxicam taken for five days was shown to work as emergency contraception. Rofecoxib, also a COX-2 inhibitor, was similarly effective. While these are not hormonal agents, COX-2 inhibitors carry the risk of their own, unique side effects.
Several non-hormonal contraceptive agents for men are under development or were tried and failed. Gossypol was in oral anti-fertility drug for men that had been under development since the 1970s. While it stopped 90% of pregnancies, it caused several severe side effects such as paralysis and irreversible sterility. As such, it has largely been abandoned. Triptolide, the molecule that is derived from a Chinese herb, also showed promise as an oral anti-sperm drug. Unfortunately, the drug worked too well and caused irreversible sterility. A more promising area of male contraception research is in molecules related to lonidamine. The derivatives of lonidamine, namely adjudin and gamendazole, are able to interfere with sperm production, but with fewer toxic side effects, especially gamendazole. Unfortunately, permanent sterility is still a problem. Nevertheless, a newer lonidamine derivative currently called CDB-4022 appears to be both effective and reversible with no apparent adverse effects. Several other drugs such as testicular retinoic acid inhibitors, calcium channel blockers, and glycosphingolipid synthesis inhibitors, and bromodomain BRDT inhibitors are still under laboratory investigation.
Male contraception is considered the Holy Grail of contraception research. Other than a condom or vasectomy, men have very few options when it comes to preventing pregnancy. Most research efforts have focused on developing The Pill for men. Instead of containing oestrogen and progesterone, a hormonal contraceptive for men may contain testosterone, progestin, and gonadotropin releasing hormone antagonists. Unfortunately, sperm can live for up to two months after they have been produced in the testes. So, even if the man starts taking a male version of birth control, it could take eight weeks or more for him to be temporarily infertile.
Moreover, the doses of male sex hormones required to interfere with sperm production in men cause severe side effects, such as liver injury. Nevertheless, researchers are getting closer to a true male hormonal contraceptive “pill”; however, instead of a pill it will likely be best used as an implant or microchip.
Researchers in the 1970s showed that ultrasound energy could interfere with sperm production. Ultrasound energy directed to the testes for 30 min. significantly interfered with sperm creation. While modestly effective and reversible, the approach is not terribly convenient for human use.
While it is currently under the earliest phases of conception, some scientists have proposed creating a small cuff that is placed around the vas deferens, the tube that carries sperm from the testes to the urethra. When the device is controlled wirelessly, the cuff would close and prevent sperm from leaving the body. If the user again decided to be fertile, a second signal could be sent to the device that would open the cuff and allow sperm to flow normally. The development such as this is likely several years to decades away.
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