May interfere with the effectiveness of bromocriptine . Regimen may also be started on first day of menses, continued for 21 days, then skip 7 days and begin again. Some regimens contain 7 placebo tablets, so that 1 tablet is taken every day for 28 days. Given in 2 phases. First phase is 10 days of smaller amount of progestin.
Second phase is larger amount of progestin.
Some regimens contain 7 placebo tablets for 28-day regimen. Progestin amount varies throughout a 21-day cycle. Estrogen component stays the same or may vary. Some regimens contain 7 placebo tablets for 28-day regimen. Taken daily and continuously.