Researchers found that piroxicam, a nonsteroidal anti-inflammatory drug (NSAID), taken in combination with the emergency contraceptive drug levonorgestrel was significantly more effective in preventing pregnancy than levonorgestrel alone.
A randomized controlled trial published in lancet Conducted on 16 August 2023 at a leading regional and reproductive health service in Hong Kong.
Researchers studied 860 women who required emergency contraception within 72 hours of unprotected intercourse between 2018 and 2022.
Women were randomized in a 1:1 ratio to receive either piroxicam 40 mg plus levonorgestrel 1.5 mg or placebo plus levonorgestrel 1.5 mg.
Follow-up was performed 7-14 days after the next expected menstrual cycle. In the absence of normal menstruation, tests were done to confirm the presence or absence of pregnancy. The primary endpoint was determined as the rate of pregnancies with expected aborted pregnancies.
Overall, the rate of prevented expected pregnancies was significantly higher in the piroxicam plus levonorgestrel group (94.7%) compared to the placebo plus levonorgestrel group (63.4%). The risk difference is 31.3%.
Overall pregnancy rate was 0.2% (1/418) in the piroxicam group compared to 1.7% (7/418) in the placebo group.
There were no significant differences between the two groups in the progress or delay of the next menstrual period or in the profile of adverse events.
The researchers suggested that piroxicam’s synergistic contraceptive effect was the result of a post-ovulatory mechanism of action as well as during ovulation. Levonorgestrel is known to be effective only before ovulation.
Janet Barter, president of the School of Reproductive Medicine, commented on the results. “We welcome the results of this new study that may improve the efficacy of emergency contraception, which is very interesting.”
“As research results become available, we will conduct a full review of the research and provide guidance to our members,” she added.
Janet Nooney, a specialist scientific assessor for the Division of Benefit Risk Management at the Medicines and Healthcare Products Regulatory Agency, said the study raises interesting potential improvements to emergency contraception, but also highlights its limitations. Stated.
“The trial included Chinese women within a relatively narrow age and weight range, and most received treatment after unprotected intercourse before it was actually used.”
“Many other factors may contribute to emergency contraceptive failure, such as during the menstrual cycle during which emergency contraception is taken. It is not yet clear whether it is applicable for everyday use.”
Nooney also expressed concern about the safety profile of piroxicam, which is only licensed in the UK as second-line therapy for symptomatic relief of osteoarthritis, rheumatoid arthritis and ankylosing spondylitis.
“Importantly … oral piroxicam tablets are no longer recommended.” [in the UK] It is associated with severe gastrointestinal side effects and rare but fatal skin reactions, making it suitable for acute analgesia and inflammatory conditions. “
“These side effects may limit its suitability for widespread use in combination with emergency contraception,” she added.