Blocking sperm production or delivery
With the ever growing world population, contraception is an important health issue for the 21st century. About 50% of couples who are of reproductive age either do not have access to or choose not to use modern contraceptives methods. Currently there are multiple methods available for the woman, including oral contraceptive pills (“birth control pills”), the “day after” pill, implants, intrauterine devices, cervical caps, diaphragm, female condom and tubal ligation. For the man, contraceptive choices are limited.
AVAILABLE MALE METHODS
All forms of male contraception work by interfering with sperm production or delivery. The goal of male contraception in to achieve azoospermia, the absence of sperm in the ejaculate.
STANDARD AND ACCEPTED MALE METHODS
- Coitus interruptus involves withdrawing the penis at the time of ejaculation. This is a technique that not widely accepted and not perfected by most men. The failure rate is high.
- Periodic abstinence, or the rhythm method, is when the couple does not have intercourse at the time the woman is considered fertile. This requires knowledge and participation of the woman who must understand when the fertile period is. Failure rates with this technique are very high also.
- Condoms. These are used by approximately 40-50 million men with a failure rate of about 15%. The advantage of latex condoms is that they protect against sexually transmitted diseases. The non-latex condoms may be more sexually pleasing, but are more expensive and do not protect against disease.
- Vasectomy is a simple office surgical procedure usually performed by a urologist. The vas deferens (the tubes that carry sperm out of the testicles) are cut, thus preventing sperm from coming out in the semen. Vasectomy offers permanent (though reversible) contraception with extremely low risk of complications. The success rate with this is probably the best compared to any permanent or temporary sterilization procedure available to men or women.
EXPERIMENTAL METHODS OF BIRTH CONTROL FOR MENHORMONAL METHODS OF MALE CONTRACEPTION
Hormonal methods act by decreasing testosterone production of the testes which in turn lowers sperm production. The production of sperm and the production of male hormones (one of the male hormones is testosterone) are closely related so it is difficult to suppress sperm production without also suppressing the production of male hormones (androgens).
Androgens are responsible for libido, sexual performance, secondary sexual characteristics, muscle mass and strength. The goal of hormonal methods of contraception is to provide a safe, effective and reversible contraception to couples. Presently, there are several hormonal methods being tested in clinical trials. Current clinical trials, however, reveal that azoospermia cannot be achieved in all men.
- Androgens. The classical androgen used to suppress sperm production has been testosterone enanthate given intramuscularly in a weekly dose. There are newer androgen preparations that are applied directly to the skin. This may cause sterility but will not affect libido and sexual performance. However, it is not always reversible.
- Androgens and progestogens. Combining progestogens (another hormone) with androgens appears to provide greater contraceptive effect. This combination allows lowering the dosage of the androgens.
- Anti-androgens. Although these can suppress sperm production, they are accompanied by a marked decrease in sexual function, thus requiring testosterone to also be used.
- Gonadotropin releasing hormone agonists (GnRH) suppress testicular function. These drugs have been used in the last decade to cause “medical castration” and eliminate the need for either orchiectomy (surgical removal of the testicle) or estrogen treatment in males with prostate cancer.