is not an ECP(emergency contraceptive pill
) but an OCP(Oral contraceptive pill) , but an OCP can be used as an effective ECP by increasing the number (4 tabs 12 hr apart) of tablet which exactly you have done here.
Actually difference between OCP & ECP is nothing but dosages.
OCP- Oestrogen-30mcg, Progesterone- 15mcg
ECP- Oestrogen- 50 mcg, Progesterone- 25 mcg.
Dose for emergency contraception-
ECP- 2 tab at 12 hr interval
OCP- 4 tab at 12 hr interval
Thus Here Nordette is an effective ECP.
It is unlikely to be implantation
bleeding as failure rate of ECP is only 0.1%.
Best of Luck.