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.
You will take your first pill on the first day of your period or on the first Sunday after your period begins. You may need to use back-up birth control, such as condoms or a spermicide, when you first start using this medicine. Follow your doctor's instructions. Take one pill every day, no more than 24 hours apart.