Letrozole, misoprostol combination ineffective for terminating pregnancy?

For medication abortion, a single dose of letrozole 30 mg prior to misoprostol 800 mcg buccally is not effective, according to a pilot study published in the journal Contraception.

“We applied for a grant to examine the potential of 3 new abortifacients,” said principal investigator Tara Shochet, a director at Gynuity Health Projects in New York City. “After exploring the published literature, we selected letrozole as the most promising. We developed the pilot study protocol based on past findings and interest in simplifying the regimen.”

The study enrolled 40 women seeking medication abortion up to 63 days’ gestation at a single Planned Parenthood Association of Utah (PPAU) site in Salt Lake City between January 10, 2022, and March 8, 2022.

The mean age of participants was 25 years, with 53% having had a previous pregnancy, 18% with a previous medication abortion, and 3% with a previous surgical abortion.

All patients took letrozole 30 mg (12 x 2.5 mg tablets) orally on the same day of study enrollment. They also received misoprostol 800 mcg (4 x 200 mcg tablets) to administer buccally 2 days later. An additional 800 mcg of misoprostol to take buccally was also provided in case patients did not have any bleeding within 24 hours following the first misoprostol dose.

Patients returned 7 to 10 days after the first day of study enrollment to assess abortion outcomes and side effects.

In total, 93% of patients returned for follow-up and 5% went to another facility from which research staff obtained outcome data.

Overall, 74% of patients (95% confidence interval [CI]: 60% to 89%) achieved a complete abortion; 10% ( 95% CI: 0.3% to 20%) had an incomplete abortion and opted for aspiration; and 15% (95% CI: 4% to 27%) had an ongoing pregnancy.

“While we did not know how well the selected regimen would work, we were both surprised and disappointed by the rate of pregnancies that were not ended by the regimen,” Shochet told Contemporary OB/GYN®.

Of the ongoing pregnancies, 83% (5 of 6 patients) had a corresponding gestational age at the initial visit of 42 days or less. The sixth patient was 61 days gestation.

Furthermore, 3 of the 6 patients with an ongoing pregnancy had taken the second dose of misoprostol.

All patients with follow-up reported taking the first dose of misoprostol, whereas 27% (n = 10) also took the second dose, but only 3 did so due to no bleeding.

Overall, 51% of patients reported side effects after letrozole and prior to misoprostol, including nausea (32%), diarrhea (19%), and chills (16%), while 5% rated these effects as severe.

Side effects following misoprostol occurred in 89% of patients, which was expected based on previous literature.

No serious adverse events were reported by any patient.

In total, 78% of patients were satisfied or very satisfied with the overall abortion process. And all but 1 patient (97%) found their side effects to be acceptable or felt neutral about them.

A full 88% of patients would select the regimen again if they needed abortion care, and 91% would recommend it to a friend.

“Although patients deemed the single dose of multiple pills acceptable, the regimen that we used was not successful enough to warrant further study,” Shochet said.

Letrozole is an attractive option as a potential alternative to mifepristone, as it is both low-cost and widely available. “However, given the limited available evidence to date, further research with letrozole would be needed to determine a better regimen and then establish the added benefit of using letrozole in combination with misoprostol for medication abortion,” Shochet said.

Disclosure

Shochet reported no relevant financial disclosures.

Reference

Shochet T, Turok D, Frye LJ, et al. Single dose letrozole and misoprostol for termination of pregnancy through 63 days’ gestation: a pilot study. Contraception. Published online December 14, 2022. doi:org/10.1016/j.contraception.2022.109924