Hi Once taken the I-Pill will remain effective up to 72 hrs. The post coital emergency contraceptive pills like I-Pill are effective in preventing pregnancy after unprotected sex if taken as early as possible but within 72 hours. Since you have already taken the I-Pill one hour ago, the high doses of Progesterone hormone present in the I-Pill causes certain changes that make unfavorable condition of the fertilized egg for implantation into the uterus and thus is effective for 72 hours. They remain effective when begun up to 72 hours after sex. So, there is actually no need for taking another pill at all. But remember that an I-Pill is an emergency contraceptive & should be reserved only for emergency and should be avoided on regular basis. Hope this answers your query. Take care.