The effect of a continuous regimen of drospirenone 3 mg/ethinylestradiol 30 μg on Cox-2 and Ki-67 expression in the endometrium

Abstract

Objective To study Cox-2 expression in relation to bleeding patterns in patients using an oral contraceptive containing 3 mg of drospirenone and 30 μg of ethinylestradiol (DRSP/EE).

Methods Forty-three patients of reproductive age with symptoms of menorrhagia and dysmenorrhoea, who were submitted to endometrial resection, were enrolled. Twelve patients were in the proliferative phase and the remaining 31 were either currently using DRSP/EE or had discontinued its use four to eight days prior to hysteroscopy. Cox-2 and Ki-67 expression were determined in the endometrium using immunohistochemistry.

Results Cox-2 expression was significantly inhibited in the glandular epithelium of patients who became amenorrhoeic during DRSP/EE use; however, in patients with breakthrough bleeding and in those who had stopped oral contraceptive use, a significant increase occurred in Cox-2 expression in the endometrium. Ki-67 expression decreased significantly during DRSP/EE use, but returned to proliferative phase values four to eight days after discontinuation of treatment.

Conclusion These results suggest that endometrial bleeding during DRSP/EE use is associated with an increase in Cox-2 expression in the endometrium. A similar increase was also seen four to eight days following discontinuation of the oral contraceptive.

Keywords:

• Drospirenone
• Cox-2
• Breakthrough bleeding
• Endometrium
• Extended regimen
• Dysmenorrhoea

Declaration of interest: One of the authors (HM) is a speaker for Libbs Farmacêutica in Brazil on continuous contraception. The authors alone are responsible for the content and the writing of the paper.