- A common morning-after pill was more effective when taken with a painkiller drug in a small study.
- 95% of women who took both medications at the same time did not get pregnant after unprotected sex.
Taking a painkiller at the same time as Plan B could make the emergency contraceptive even better at reducing the risk of getting pregnant after unprotected sex, a new study suggests.
The findings, published in The Lancet on Wednesday, were based on a randomized trial of 836 women at the Family Planning Association of Hong Kong. The study found that patients who were given a dose of piroxicam — an anti-inflammatory drug typically given to people with arthritis — alongside the popular emergency contraceptive pill levonorgestrel, branded as Plan B, were significantly less likely to fall pregnant than those who took levonorgestrel alone.
Levonorgestrel is one of the most commonly used emergency contraceptives in most countries, according to a press release from The Lancet, and works by preventing or delaying ovulation but is not effective post-ovulation.
A group of 418 women seeking emergency contraception within 72 hours of having unprotected sex were given levonorgestrel and piroxicam, while another 418 women were given levonorgestrel and a placebo. The women were given follow-up appointments one to two weeks after their next expected period, and if their period had not come they were given a pregnancy test.
Researchers at the University of Hong Kong's Department of Obstetrics and Gynecology found that 95% of women who took both medications did not get pregnant, while the same was true for only 63% of those who took just levonorgestrel.
And as well as making Plan B more effective in preventing pregnancy, piroxicam did not cause more side effects compared with the placebo.
Dr. Sue Lo, a co-author of the study who works at the Family Planning Association of Hong Kong, told The Guardian: "Finding out that there is a widely available medication which increases levonorgestrel's efficacy when they are taken together is really exciting."
More research is needed before the public can start combining these pills
The effectiveness of levonorgestrel is based on a 1998 trial that found the drug was 95% effective at preventing pregnancies if taken within 24 hours of unprotected sex, 85% if taken within 25 to 48 hours, and 58% if taken within 49 to 72 hours. But recent research suggests the efficacy of levonorgestrel might be lower, according to the study.
Professor Kristina Gemzell-Danielsson, a co-author from the Karolinska Institute, said in a press release that while levonorgestrel targets the luteinizing hormone — which stimulates reproductive processes in the body — piroxicam might work by affecting what are known as prostaglandins: a group of hormone-like lipids that are involved in processes such as ovulation, fertilization, and embryo implanation. However, the trial did not look at how piroxicam functions.
Dr. Janet Barter, president of the Faculty of Sexual and Reproductive Healthcare at the Royal College of Obstetricians and Gynaecologists, UK, who was not involved in the study, said in a statement: "We welcome the findings of this new study which has the potential to improve the efficacy of emergency contraception, which is very exciting.
"However, it is important to note that this was a relatively small study and further robust studies will be required to establish safety and effectiveness of this combination of drugs for all patients."
Experts as well as the authors acknowledged the limitations of the study, including the fact that most participants were Asian and weighed less than 70kg. More research is needed to see whether the findings will apply to a more diverse range of people.