Lower-dose Hormonal Contraceptives may be Possible, Study Suggests

Photo: Reproductive Health Supplies Coalition on Unsplash

The dosage of hormones in common contraceptives could be reduced by as much as 92% and still effectively suppress ovulation, according to a computational model from University of the Philippines Diliman which is described in PLOS Computational Biology.

Constant dosage and nonconstant dosage comparison. The shaded regions in Panels (A), (C), and (E) indicate the minimum total constant dosage of exogenous estrogen and/or progesterone over 28 days that lowers maximum P4 concentration to 4.99 ng/mL. The shaded region below u1 (area under the curve or AUC) in Panel (B) is the total nonconstant dosage of exogenous E2 which suppresses the P4 level to 4.43 ng/mL, a reduction by about 92% of the total dosage in (A). Panel (D) illustrates the total nonconstant dosage of exogenous P4 that reduces maximum P4 to 4.66 ng/mL, a reduction by about 43% of the total dosage in (C). Panel (F) shows the combined nonconstant doses of exogenous E2 and P4 that gives a maximum P4 level of 4.31 ng/mL. Credit: Gavina et al., 2023, PLOS Computational Biology, CC-BY 4.0 (creativecommons.org/licenses/by/4.0/)

A normal menstrual cycle involves multiple phases which are regulated by the endocrine system and influenced by levels of various hormones. The most contraceptive approaches, including pills, injectables and implants, involve the administration of exogenous oestrogen and/or progesterone to block ovulation.

In the new study by Brenda Lyn A. Gavina, PhD student, and her collaborators, researchers used data on hormone levels in 23 women aged 20 to 34 with normal menstrual cycles.  The team developed computational models depicting the interactions between various hormone levels as well as the impacts of exogenous hormones.

The model provided evidence that it is possible to reduce the total dose by 92% in oestrogen-only contraceptives, or the total dose by 43% in progesterone-only contraceptives, and still prevent ovulation. By combining oestrogen and progesterone, the doses of each hormone could be reduced even further. In addition, the model showed the importance of timing the hormones during the cycle, pointing toward ways that exogenous oestrogen and progesterone could be given during only certain phases of the menstrual cycle rather than at steady constant doses.

“These results may give clinicians insights into optimal dosing formulations and schedule of therapy that can suppress ovulation,” the authors say.

Source: EurekAlert!