11-Beta-MNTDC: “The Pill” for Men

Medically Reviewed by Traci C. Johnson, MD on May 23, 2024
5 min read

More than 60 years after women first got access to a daily pill to prevent pregnancy, research is still underway to make a similar option available for men. Scientists have been at work on this since the 1970s. Today, two experimental male birth control pills, both developed by a team of researchers at University of Washington and Los Angeles Biomedical Research Institute, have begun human clinical trials: DMAU (dimethandrolone undecanoate), the first pill of its kind, and now what researchers call its “sister compound” 11-beta-MNTDC (11-beta-methyl-19-nortestosterone dodecylcarbonate).

While the latest developments in 11-beta-MNTDC research are exciting, it may still be years before men can say to their female partners, “Don’t worry – I’m on the pill.”

This particular male birth control pill has only gone through a phase I clinical trial. Phase I trials typically include fewer than 100 people. Their purpose is to make sure the experimental drug is safe and won’t cause anyone any harm. These early tests aren’t enough to prove that a drug works. Once drug developers clear this first hurdle, they get approval to move onto phase II.

The phase I trial of 11-beta-MNTDC, the results of which were published in the Journal of Clinical Endocrinology and Metabolism in March 2020, included 42 men. Though the study was small and brief, preliminary data suggest that the drug will do what researchers intend for it to do: lower testosterone levels, which in turn will suppress sperm production. But the objective of the study was not to test the drug’s effectiveness. All participants committed to using other forms of birth control throughout the course of the 28-day trial. The trial achieved its main objective: It passed the necessary safety tests and got the green light to advance to the next phase. But the researchers haven’t yet announced plans for a phase II trial.

Based on this research, here’s what’s known about 11-beta-MNTDC.

11-beta-MNTDC is a pill that, if proven safe and effective, men would take daily to lower their sperm count enough that they were no longer able to make a woman pregnant. The pill blocks the body’s secretion of testosterone and progesterone, two hormones that the male body needs for sufficient sperm production. Without these hormones, sperm counts plummet.

Like birth control pills that women take, men would have to take this pill every day in order for it to work. It would take about 60 to 90 days on this pill to cut down sperm production enough to prevent pregnancy. Couples would need to use another form of contraception in the first 60 to 90 days. Based on research so far, it looks like the pill might be most effective when taken with food.

Researchers haven’t yet hammered out the best dose for this drug. The ideal dose would be the smallest one needed to get the desired effect. The phase I safety trial tried some of the men on 200 milligrams a day and others on 400 milligrams each day. An earlier study, which included just 12 men, looked at how well they tolerated escalating doses of 100, 200, 400, and 800 milligrams both with and without food.

So far, researchers have tested the male birth control pill on healthy men ages 18 to 50 only. The men in the study didn’t have any chronic health conditions or substance use problems. No one had a BMI higher than 33.

Researchers need to do more tests to find out whether this pill would have any risks for older men, men who take certain medications, or those with certain health conditions.

While studies so far haven’t uncovered any serious side effects of 11-beta-MNTDC, blood tests did reveal the following consequences:

Cholesterol trending in the wrong direction. Men in both the 200 milligram and the 400 milligram groups saw increases in bad cholesterol (LDL) and decreases in good cholesterol (HDL).

A rise in creatinine levels. Men in both groups saw a slight rise in their creatinine levels. Large increases in this waste product made by your muscles and filtered out by your kidneys would suggest the drug was causing kidney trouble. Researchers plan to further explore the pill’s impact on kidney function in future studies that last longer and include more people.

A drop in SHBG (sex hormone binding globulin). Men in the study had a drop in this protein that the liver creates and which attaches to sex hormones in both men and women. Naturally low SHBG in men can be a risk factor for type 2 diabetes and other metabolic conditions, but it’s unclear whether artificially lowering it with medication brings that same risk.

Men on the pill complained of a few unwanted consequences, too. They included:

  • Acne
  • Weight gain
  • Headaches
  • Fatigue
  • Mild mood changes

For a small number of the men, the pill seemed to cause some sex problems. Five of the 42 men reported a lower desire for sex after starting the pill. Three had some level of erectile dysfunction or trouble ejaculating.

It will take longer-term studies that include more men to determine just how common and how serious any of the side effects may be. For now, these side effects didn’t keep the drug from qualifying for a phase II study.

Researchers asked the 42 men what it was like to be on the pill. Here’s what they said: 

None of the men had any problem sticking with the daily pill. A whopping 92% of them said they’d recommend it to other men. More than half of the men said that their 28-day experience with the drug went better than they expected it to. More than 60% of them said they’d be willing to pay for this form of contraception. (They got it for free in the clinical trial.)

It’s a long road from a phase I clinical trial to the shelves of your local drugstore. The male birth control pill 11-beta-MNTDC needs to go through more rigorous testing on thousands of people – a process that will take years – before the FDA will authorize a drugmaker to manufacture this drug.

Most drugs never make it this far. Seventy percent advance past phase I. Among the drugs that go through phase II, which can take up to 2 years, just 33% move forward. Twenty-five percent to 30% pass phase III, which can take up to 4 years, and go onto the final phase: IV. All of that is to say, a male birth control pill might not figure into your own family planning. But in the event you do start a family, “the pill” might be a contraception option for your sons.