Levonorgestrel at emergency contraception dose has no effect on ciliary beat frequency and muscular contraction of the human fallopian tube: an in vitro experimental study.

BACKGROUND

Levonorgestrel (LNG) acts as an emergency contraceptive mainly by inhibiting or postponing ovulation. We carried out this study to investigate whether LNG at concentration relevant for emergency contraception (EC) affect ciliary beat frequency and muscular contraction of the human Fallopian tube, which might contribute additional actions for EC.

METHODS

This was an in vitro experimental study on human Fallopian tube tissue collected from ten women undergoing hysterectomy. The tubal explants were cultured in vitro, primed with oestradiol and progesterone at concentrations resembling the physiological early luteal phase, and treated with LNG at 0, 1, 10 and 100 ng/ml concentrations. Ciliary beat frequency was measured from the tubal epithelial strips, and the basal tone, amplitude and frequency of contractions were recorded from longitudinal smooth muscle strips. These parameters at different LNG concentrations were compared against the control (LNG 0 ng/ml).

RESULTS

Treatment of tubal tissue strips with LNG at all concentrations studied did not significantly alter the ciliary beat frequency nor basal muscle tone (p > 0.05 for both) compared with control. Significant reduction in the amplitude and frequency of tubal muscular contractions was shown after treatment with LNG only at 100 ng/ml (p < 0.05 for both) but not lower concentrations (p > 0.05) compared with control.

CONCLUSION

LNG did not significantly inhibit ciliary beat frequency and muscular contraction of the human Fallopian tube at the doses used for EC, suggesting that the Fallopian tube is unlikely a target for the EC action of LNG.