Dienogest effective against primary dysmenorrhoea

The use of dienogest at 1 mg per day to treat primary dysmenorrhoea is well tolerated and attenuates symptoms of pain, as shown in the results of a phase II trial.

Conducted at 20 study sites, the trial randomized 235 women with primary dysmenorrhoea to receive dienogest (0.5 mg, n=49; 1 mg, n=48; or 2 mg, n=49), placebo (n=46), or ethinylestradiol 0.02 mg/drospirenone 3 mg (EE/DRSP; an open-label reference drug; n=47) orally once daily for 12 weeks.

Researchers used the dysmenorrhoea score (0–6) and visual analogue scale (VAS; 0–100 mm) to evaluate lower abdominal pain and/or low back pain at baseline and every 4 weeks after treatment initiation.

At week 12, the primary endpoint of change from baseline in the dysmenorrhoea score proved to be significantly greater across all doses of the study drug compared with placebo (0.5 mg arm, p=0.003; 1 mg arm,  p<0.001; 2 mg, p<0.001). The 1- and 2-mg doses of dienogest specifically exerted a beneficial effect on pain that was at least equivalent to that of the reference drug.

Adverse events occurred in 56.5 percent of patients in the placebo arm, 97.8 percent in the dienogest 0.5-mg arm, 95.7 percent in the 1-mg arm, 95.9 percent in the 2-mg arm and 83.0 percent in the EE/DRSP arm. Irregular uterine bleeding was the most common adverse drug reaction, occurring with similar frequency in the dienogest arms.

Meanwhile, serum oestradiol concentration significantly dropped in patients treated with the 1-mg dose, but not the 2-mg dose, compared with placebo.

Based on the present data, the researchers pointed out that 1 mg/day is the optimal and clinically recommended dose of dienogest, because it does not suppress oestradiol production.