According to a recently published randomized controlled trial, lancetpiroxicam, an anti-inflammatory drug often prescribed for arthritis pain, combined with levonorgestrel emergency contraception after unprotected intercourse reduces pregnancy compared with taking levonorgestrel alone.
Two types of emergency contraception containing levonorgestrel or ulipristal acetate are the most widely used emergency contraceptive methods in most countries, with levonorgestrel tablets available in more countries than ulipristal acetate tablets. is. Both birth control pills work by preventing or delaying ovulation, but neither are effective after ovulation.
The accepted efficacy of levonorgestrel is based on the following results: Trial since 1998 In this study, levonorgestrel prevented 95% of expected pregnancies if taken within 24 hours of unprotected sex, 85% if taken within 25-48 hours, and 58 if taken within 49-72 hours. % were prevented. However, more recent research suggests that levonorgestrel may be less effective.
“Levonorgestrel emergency contraception is one of the most popular options for emergency contraception in many parts of the world, so knowing that there are drugs that are widely available that are more effective when combined with levonorgestrel is an “I’m really excited,” said Dr. Sue Lo of the Hong Kong Family Planning Association, a collaborator on the study.
Lead author of the study, Dr Raymond Lee from the University of Hong Kong, added: “Our study is the first to suggest that a readily available and safe drug taken with levonorgestrel tablets can prevent more pregnancies than levonorgestrel alone. We hope this will ultimately lead to changes in clinical guidelines so that more effective emergency contraception is available to women around the world.”
The study was conducted at a major community reproductive health service in Hong Kong from August 2018 to August 2022. Women requiring levonorgestrel emergency contraception within 72 hours of unprotected intercourse were randomized to receive a single dose of either supervised levonorgestrel 1.5 mg or piroxicam. 40 mg or placebo tablets. Participants and participating health professionals did not know which group received which treatment. A follow-up appointment was made 1-2 weeks after her next menstrual period was due. During the consultation, if you had not had a normal period by that time, a pregnancy test was taken. The percentage of aborted pregnancies out of expected pregnancies was calculated based on an established model published in 1998.
Of the 836 women followed, 418 women who received piroxicam and levonorgestrel had one pregnancy, and 418 women who received placebo and levonorgestrel had seven pregnancies. The expected rate of pregnancy without contraception was estimated at 4.5% (19/418) for her in both groups. Therefore, the rate of pregnancies prevented after co-treatment with piroxicam and levonorgestrel was 95% (18/19) compared to 63% (12/19) in patients taking levonorgestrel and placebo.
There was no significant difference in the incidence of side effects between patients co-treated with piroxicam and placebo.
Another collaborator, Professor Kristina Jemsel-Danielsson of the Karolinska Institutet, said, “Levonorgestrel prevents pregnancy by blocking or delaying the surge of luteinizing hormone that disrupts the ovulation process. Piroxicam , may exert their effects by targeting a different class of hormones, prostaglandins, which promote several reproductive processes such as ovulation, fertilization and embryo implantation. , we speculate that piroxicam may provide both pre-ovulatory (by blocking the ovulatory process) and post-ovulatory (by blocking embryo implantation) contraceptive effects, but our The trial did not investigate piroxicam’s mechanism of action or further research, and we need to confirm this.”
The authors acknowledge several limitations of this study, including the possibility of generalizing the findings to other situations. Because the study excluded women who were currently or recently using hormonal contraceptives and women who had multiple unprotected sexual intercourses before taking emergency contraception, piroxicam plus levonorgestrel combination therapy It is unclear whether it would have the same effect when applied to the following women: Women in such situations.
Dr. Erica Cahill of Stanford University School of Medicine, who was not involved in the study, wrote in the linked comments: Oral administration of piroxicam 40 mg increases efficacy with fewer side effects. These conclusions may not apply to all patients, as the study was limited to a specific population and most of the participants were of Asian descent and weighed less than 70 kg. Given that levonorgestrel emergency contraception is less effective in obese people, the efficacy shown here may not generalize to patients with high BMI. ”
Reference: “Oral emergency contraception with levonorgestrel and piroxicam: a randomized, double-blind, placebo-controlled trial.” Raymond Hang Wun Li, Sue Seen Tsing Lo, Kristina Gemzell-Danielsson, Carol Ho Yi Fong, Pak Chung Ho, Ernest Hung Written by Yu Ng, August 16, 2023 lancet.
DOI: 10.1016/S0140-6736(23)01240-0
The study was funded by the University of Hong Kong Department of Obstetrics and Gynecology and was conducted by researchers at the university.