Mast cells. Mast cells and basophils are generally thought to be the major sources of histamine and can themselves be modulated by histamine as they express H 1, H 2 and H 4 receptors, although how this varies between different mast-cell types is not yet clear.
3. The pill is to be taken soon after unprotected sex. It should be taken preferably within 24 hours and before 72 hours or else the pill may turn useless. 4. I-pill checks pregnancy by preventing ovulation or fertilisation or implantation of the fertilised egg. 5. I-pill is 95 per cent effective if taken in time.
Dear Desperate, Post-coital contraception, the morning after pill, and emergency contraception are all names given to hormonal medication that is taken after unprotected sex to prevent pregnancy. Some birth control pills that contain ethinyl estradiol and levonorgestrel are considered safe and effective for use as emergency contraception (EC).