New Testosterone Injections Work as Male Contraceptive

Pregnancy is a big step in life for any couple. Until now, there have only been a few ways to prevent pregnancy and most of them are centered around the female. Now, there is a new monthly injection of testosterone that works as a contraceptive in men, allowing the responsibility of birth control to be shared among the sexes.

For years, scientists have been looking for a contraceptive to be the male equivalent to the Pill. The trials that were conducted in the 1990s found that weekly injections of testosterone reduced the sperm counts for 98 percent of the men, and the effects disappeared when the injections were stopped. However, the researchers thought that the weekly injections would be considered too unpopular and troublesome with men to be a very useful method of contraception.

Since then, researchers have been experimenting with injections that are oil-based. They combined the testosterone with tea seed oil which means that once it was injected, it was absorbed very slowly by the body. This also means that the effect of a single injection could last for much longer.

A new, large-scale study has looked at how well the monthly injections of testosterone has worked as a contraceptive and how safe they really are. The recent study looked at approximately 1,045 Chinese men that were between the ages of 20 and 45, had fathered at least one child in the two years prior to the study, and were in a stable relationship.

For six months, the men that participated in the study took monthly injections of testosterone in their buttocks. After that time, most of the men had very low sperm counts. However, the testosterone injections failed to lower the sperm count in about 5 percent of the men.

If the injections were successful, the men continued to take them for two years. However, many of the participants dropped out over time, so only 733 actually completed the trial. Also during the trial, the sperm count rose again for just over 1 percent of the men, and there were nine pregnancies during the two years. Overall, after the first year of the study, there was 1 pregnancy for every 100 men that participated. At the end of the second year, the pregnancy rate was fractionally higher at 1.1 per 100 men.

Condoms, when they are used perfectly, have about a 2 in 100 pregnancy rate a year. With the female contraceptive pill, the pregnancy rate is approximately 0.3 in 100. It is very important to remember that most of the contraceptives are a lot less effective in the real world than these ‘"perfect use" figures suggest, because people can forget to take a pill or the condom can fail to work properly.

An important question is whether the men’s sperm count rose again after the testosterone injections were stopped. For most of the men it took approximately 200 days for their sperm count to return to normal, however, 17 of the men still had not recovered their fertility after one year. Most of the men who participated had a normal sperm count after an extra three months, but two of the men were still not producing sperm after this time period.

The side of effects of the injections included tenderness at the injection site, a rash or acne, and some men experienced changes in their sex drive. These changes varied from man to man, but the most common side effect was a sex drive that was higher.

The next question is, what does this mean for me? The injection is currently being tested in Phase III trials, which are considered the largest scale human trials that are carried out before a new drug is released to the market. If a new medication is safe and effective in Phase III trials, its manufacturer can then apply to the appropriate regulatory agency for a license to manufacture and sell the product. There is no definite timescale, but it is usually a few years from the successful completion Phase III trials to the launch of the new product.