Developing a male contraceptive pill

Developing a male contraceptive pill
Science of Life

 

When we think of artificial contraception we think primarily of the ‘contraceptive pill’, easily the most common form of contraception used by women. There is no corresponding contraceptive pill for men, but efforts are underway to develop such contraception. It is predicted that if such a male pill became available the worldwide incidence of unwanted pregnancies would plummet. But developing effective male contraception is technically difficult and slow.

Conception occurs when a sperm cell from the father fuses with an egg cell from the mother to produce a zygote, a new human being and the first stage of the human embryo. This process is also known as fertilisation. The fertilised egg embeds in the wall of the mother’s womb and grows and develops until ready to be born nine months later. Contraception works by preventing the sperm and the egg from interacting.

The human female releases one or two eggs, available to be fertilised by sperm, per month. This process is called ovulation. The female contraceptive pill, taken orally, contains two hormones (estrogen and progestin) that act to prevent ovulation, i.e. the monthly release of eggs ready for fertilisation. If no eggs are released there is nothing for the sperm to fertilise and so conception is prevented. The contraceptive pill also thickens mucus in the oviduct making it difficult for sperm to swim and find the egg in any event.

The traditional male contraceptive is the condom, a barrier sheath that prevents sperm from entering the woman’s reproductive system.

The first recorded use of the condom was by the Italian anatomist Gabrielle Falloppio (1523-1562) one of the most important anatomists and physicians of the 16th Century. The name will sound familiar because Falloppio also discovered the female fallopian tubes.

Falloppio’s condom was made of linen cloth, tied securely in place with a ribbon. Falloppio intended his condom to protect against contracting syphilis and other sexually transmitted diseases and probably didn’t realise it could also prevent pregnancy. Condoms have been improved several times over the years. In the early 1700s condoms made from animal intestines were popular. In 1920 latex condoms were introduced and polyurethane was introduced in 1994.

The vasectomy is another form of male contraception where the tube (vas deferens) carrying the sperm from the testes to be mixed into the semen is cut. The ejaculated semen is now free of sperm.

Vasectomy can sometimes be reversed by expensive micro-surgery. Vasectomy was first performed by Dr Albert Oschner in 1897 on two chronic criminals as a humane alternative to castration – eugenics was popular at the time and the aim was to eliminate ‘criminal genes’ from the general gene pool.

Great efforts have been made to develop a male version of the female contraceptive pill, i.e. an oral medication that a man could take that would either prevent the production of sperm or render the sperm inactive, but whose effects would disappear when ingestion of the contraceptive ceased. These efforts have yet to bear fruit in the form of a medically approved and widely available male contraceptive pill, but promising trials are underway. A topical gel that blocks sperm production is under mature development, and also a non-surgical form of vasectomy.

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Why have we had a female contraceptive pill for a long time now but no similar male pill yet?  One reason is that it is more difficult to deal with male biology. A man makes hundreds of millions of sperm cells per day and a typical ejaculation contains 250 million sperm. Women on the other hand release only one or two eggs per month, so stopping male sperm production is a much bigger task than shutting down egg release. Any male contraceptive pill also must be at least as safe and effective as the female pill. Because of these difficulties pharma companies have backed off trying to develop a male contraceptive pill. Most research and funding in this area is now left to Government.

The male contraceptive pill that is most advanced in development is a gel called Nestorone-Testosterone. This gel contains two hormones that reduce the production of sperm by the testes to a level below that required to cause pregnancy. The gel is applied to arms and shoulders daily. Large trials are now underway but it is projected that it will take up to 10 years to develop a successful product.

A non-surgical vasectomy procedure is a promising new development in the field of male contraception. This development, pioneered by researchers in India, is called RISUG which stands for reversible inhibition of sperm under guidance. This involves injecting a polymer gel into the vas deferens tube to block sperm flow rather than cutting the vas deferens. The blockage can be reversed by another injection of a substance that dissolves the blocking gel. This procedure is said to be 98% effective at preventing pregnancy (the same effectiveness as condoms if used properly) and has no significant side effects.

As readers know, the Catholic Church teaches that artificial contraception is morally wrong because every act of sexual intercourse between a husband and wife should be open to the possibility of procreation. The biological function of sexual intercourse clearly is procreation and the Church teaches that to artificially frustrate this procreative potential violates natural law. The two aspects of sexual intercourse, procreative potential and sexual pleasure, should not be artificially separated. Pope Paul VI predicted in his 1968 encyclical Humanae Vitae that if artificial contraception became widespread in society many negative consequences would follow, eg. promiscuity, where sex freed from ‘risk’ of pregnancy is seen as a leisure activity, and the spread of sexually transmitted diseases.

On the other hand, the Catholic Church approves of natural family planning. This means that a husband and wife who have good reason not to want another child born at any given time can use the natural family planning method to achieve this end. The woman monitors her monthly cycle so that she knows when she is ovulating and she and her husband abstain from sexual intercourse when she is fertile, i.e. from a period of seven days before ovulation to two days after ovulation.

William Reville is an Emeritus Professor of Biochemistry at UCC.   

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