Postinor-1 (levonorgestrel)

Postinor-1 general information

What is Postinor-1 used for?

Postinor-1 (also known as Plan B in the US) is used as an emergency contraceptive to prevent unwanted pregnancy after unprotected sexual intercourse; or if a contraceptive method that has been used has failed. Postinor-1 1.5mg, also known as “the morning-after pill" is a single treatment and must be used within 72 hours of unprotected sex to be effective in reducing your chances of becoming pregnant, but it will not have any effect if there is a chance that you are already pregnant.

How does Postinor-1 work?

Postinor-1 (also known as Plan B in the US) contains levonorgestrel, a synthetic progestogen that is used as an emergency contraceptive to protect against unwanted pregnancy following unprotected sex. Preparation for pregnancy depends on a complex interaction between the female sex hormones produced by the ovaries; oestrogen, which stimulates ovulation (release of an egg from the ovaries), and progesterone which prepares the endometrium (lining of the uterus) for implantation of an embryo; as well as other regulating hormones, produced by the hypothalamus in the brain and the pituitary gland. Levonorgestrel in Postinor-1 1.5mg is the same progestogen used in regular contraceptive pills but used at a much higher concentration. It is thought to work primarily by preventing ovulation and fertilisation if you had unprotected sex in the first 2 weeks of the month before ovulation has taken place, which is when likelihood of fertilisation is the highest. If you had unprotected sex in the second 2 weeks of the month levonorgestrel in Postinor-1 helps reduces the chances of implantation by preventing changes in the endometrium that are needed for implantation of the fertilised egg. Postinor-1 will not prevent a pregnancy continuing if fertilization and implantation has already taken place.

What does Postinor-1 contain?

Postinor-1 (also known as Plan B in the US) contains the active ingredient levonorgestrel (1.5 mg), a synthetic progestogen that is used for emergency contraception. It also contains Potato starch, maize starch, colloidal silica anhydrous, magnesium stearate, talc, lactose monohydrate.

Postinor-1 for emergency contraception

Postinor-1 (also known as Plan B in the US) contains levonorgestrel, a synthetic progestogen that is used as an emergency contraceptive to protect against unwanted pregnancy following unprotected sex. Levonorgestrel in Postinor-1, also known as “the morning-after pill", is thought to work primarily by preventing ovulation and fertilisation in the first 2 weeks of the month before ovulation has taken place, which is when likelihood of fertilisation is the highest. If you had unprotected sex in the second 2 weeks of the month levonorgestrel in Postinor-1 helps reduces the chances of implantation by preventing development and thickening of the endometrium (lining of the uterus) that is needed for implantation of the fertilised egg, so that a fertilised egg would not be able to implant and grow. Postinor-1 will not prevent a pregnancy continuing if fertilization and implantation has already taken place.

What are the side effects of Postinor-1?

The most commonly reported side effects when taking Postinor-1 include: Delayed period, bleeding not related to menstrual bleeding, irregular bleeding or spotting nausea, diarrhoea, vomiting lower abdominal pain, breast tenderness dizziness, headache.

When should Postinor-1 not be used?

You should not use Postinor-1 if you:

• are allergic to levonorgestrel or any ingredients in Postinor-1
• are pregnant think you may be pregnant
• are late for your last period, or your last period was unusual in any way
• have liver disease or bowel problems such as Crohn's disease
• have diabetes mellitus, heart disease or have had a stroke or have had breast cancer
• are taking medicines that interact with Postinor-1, including anticonvulsants like phenytoin, primidone and carbamazepin, barbiturates, anti-infectives like rifampicin, rifabutin, nevirapine, the antifungal griseofulvin, antibiotics like penicillin, preparations containing St John's Wort

What medications interact with Postinor-1?

Some medications interact with Postinor-1 and prevent it from working effectively, increasing your risk of becoming pregnant. If you are taking any of the following Postinor-1 may not be effective for emergency contraception.

• anticonvulsants like phenytoin, primidone and carbamazepin
• barbiturates
• anti-infectives like rifampicin, rifabutin, nevirapine, griseofulvin
• antibiotics like penicillin
• preparations containing St John's Wort

How should Postinor-1 be taken?

You should take your Postinor-1 with a glass of water swallowed whole, as soon as possible after you have had unprotected sex, preferably within 12 hours but no later than 3 days after. You should only use Postinor-1 for emergency contraception not as a regular method of contraception. If you use Postinor-1 more than once in a menstrual cycle this may disrupt your cycle and cause irregular periods. If you vomit within 3 hours of taking your Postinor-1 tablet, you should take another immediately. If you are already taking another contraceptive pill you can continue to use this for regular contraception.

Can you continue taking contraceptive pills with Postinor-1?

If you are already taking another contraceptive pill you can continue to use this for regular contraception at the same time as taking your Postinor-1 tablets, as Postinor-1 is intended for use only as emergency contraception not as a regular method of contraception.

How should Postinor-1 be stored?

You should store your Postinor-1 below 25°C in a cool dry place.