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Postinor-1

Levonorgestrel

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BRAND INFORMATION

Brand name

Postinor-1

Active ingredient

Levonorgestrel

Schedule

S3

See related product images

Postinor-1 1.5 mg Tablets

Consumer medicine information (CMI) leaflet

Please read this leaflet carefully before you start using Postinor-1.

• Download CMI (PDF)
• Download Large Text CMI (PDF)

What is in this leaflet

This leaflet answers some common questions about Postinor-1.

It does not contain all the available information.

It does not take the place of talking to your doctor or pharmacist.

All medicines have risks and benefits. Your doctor or pharmacist will have discussed and considered the risks of you taking Postinor-1 against the benefits they expect it will have for you.

If you have any concerns about taking this medicine, ask your doctor or pharmacist. Your doctor and pharmacist have more information.

Keep this leaflet with the medicine. You may need to read it again.

What Postinor-1 is used for

Postinor-1 is an emergency contraceptive only. Postinor-1 is not intended as a regular method of contraception. It is used to prevent pregnancy when taken within 72 hours (3 days) of unprotected intercourse (sex).

It is estimated that Postinor-1 will prevent 85% of expected pregnancies when you take it within 72 hours of having unprotected sex. It will not prevent a pregnancy every time and is more effective if you take it as soon as possible after unprotected sex.

Postinor-1 is most effective if taken within 72 hours of unprotected sex. But remember that the sooner you take it, the more likely it will prevent pregnancy.

Postinor-1 will not prevent you from catching sexually transmitted diseases. Ask your doctor or pharmacist if you have any questions about why you are taking Postinor-1.

Postinor-1 is thought to work by:

• stopping your ovaries from releasing an egg;
• preventing sperm from fertilising any egg you may have already released.

Postinor-1 can only prevent you becoming pregnant if you take it within 72 hours of unprotected sex. It does not work if you are already pregnant. If another unprotected intercourse takes place after the use of Postinor-1 (also if this is during the same menstrual cycle), the tablet will not work and there is again the risk of pregnancy.

Before you take Postinor-1

Before you start treatment with Postinor-1, your doctor or pharmacist should:

• Check you are not already pregnant if he/she suspects you may already have been pregnant before this occurrence of unprotected intercourse
• Ask you if you are taking any other medicines (see Taking other medicines)
• Ask if you suffer from high blood pressure
• Advise you of the need for careful use of a barrier method of contraception until you have your next period
• Advise you to see your doctor in three weeks' time, especially if you have not had a period by then
• Discuss the need for regular contraception

You should consult your doctor before you take it if:

• You have diabetes mellitus (with kidney, eye or nerve damage, or vascular disease) – Diabetes mellitus is a condition in which the body does not produce enough insulin or else the body tissues are not able to use the insulin present. This leads to hyperglycaemia (too much sugar in the blood)
• You have ischaemic heart disease (heart disease caused by reduced blood flow in the blood vessels of the heart muscle)
• You have suffered a stroke
• You have had breast cancer
• If you are pregnant or think that you may already be pregnant. This medicine will not work if you are already pregnant. If you are already pregnant, Postinor-1 cannot terminate pregnancy. Postinor-1 is not an “abortion pill”.You may be already pregnant if:- your period is more than 5 days late, or you have experienced unusual bleeding when your next period is due;- you have had unprotected sex more than 72 hours ago, and since your last period.

If any of these conditions apply to you it may not be suitable for you to take Postinor-1.

The use of Postinor-1 is not advised if

• you have a disease of your gastrointestinal tract (such as Crohn’s disease) that interferes with the digestion and absorption of your food;
• you have severe liver disease
• you have a history of ectopic pregnancy (where the baby develops somewhere outside the womb)
• you have a history of salpingitis (inflammation of the Fallopian tubes)A previous ectopic pregnancy or previous infection of the Fallopian tubes increase the risk of a new ectopic pregnancy.
• you are vomiting or have severe diarrhoea

Emergency contraception should be taken as soon as possible after unprotected intercourse.

Children and adolescents Postinor-1 is not recommended for children. The is only limited information available on Postinor-1 when taken by women aged 14-16 years and no information on its use in younger women or children

When you must not take it

Do not take Postinor-1 if:

• You are pregnant
• You have previously had unprotected intercourse more than 72 hours earlier in the same menstrual cycle, as you may already be pregnant
• You are experiencing vaginal bleeding for which the reason is not known
• You have breast cancer
• You are allergic to any of the ingredients of the tablets (See Product Description below)
• The tablets do not look quite right

Do not take Postinor-1 after the expiry date printed on the pack or if the packaging is torn or shows signs of tampering.

Taking other medicines

Tell your doctor or pharmacist if you are taking any other medicines, including those purchased from a supermarket or health food store. Some medicines may prevent Postinor-1 from working properly or Postinor-1 may affect the way other medicines work. Examples of medicines which may interfere with Postinor-1 are:

• Medicines used to treat epilepsy (e.g. barbiturates, primidone, phenytoin, and carbamazepine).
• Medicines used to treat tuberculosis (e.g. rifampicin, rifabutin).
• Medicines used to treat HIV infection (ritonavir, efavirenz).
• Medicines used to treat fungal infections (griseofulvin).
• Herbal remedies containing St John’s Wort (Hypericum perforatum)

Postinor-1 may affect the way other medicines work

• a medicine called cyclosporine (suppresses the immune system).

How often can you use Postinor-1

You should only use Postinor-1 in emergencies and not as a regular method of contraception. If Postinor-1 is used more than once in a menstrual cycle, it is less reliable and it is more likely to upset your menstrual cycle (period).

Postinor-1 does not work as well as regular methods of contraception. Your doctor, practice nurse or family planning clinic can tell you about long-term methods of contraception which are more effective in preventing you from getting pregnant.

Pregnancy, breastfeeding and fertility

If you are pregnant or breastfeeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking any medicine.

Pregnancy You should not take this medicine if you are already pregnant. If you do become pregnant even after taking this medicine, it is important that you see your doctor. Your doctor may want to check that the pregnancy is not ectopic (where the baby develops somewhere outside the womb). This is especially important if you develop severe abdominal pain after taking Postinor-1 or if you have previously had an ectopic pregnancy, Fallopian tube surgery or pelvic inflammatory disease.

Breastfeeding The active ingredient of this medicine is excreted into your breast milk. Therefore, it is suggested that you take your tablet immediately after a breastfeeding and avoid nursing at least 3 days following taking this medicine.

Fertility Postinor-1 increases the possibility of menstruation disturbances which can sometimes lead to an earlier or later ovulation date resulting in a modified fertility date. Although there are no fertility data in the long term, after treatment with Postinor-1 a rapid return to fertility is expected and therefore, regular contraception should be continued or initiated as soon as possible after Postinor-1 use.

How to take Postinor-1

Always use this medicine exactly as described in the leaflet or as your pharmacist or doctor has told you. Check with your doctor or pharmacist if you are not sure.

Take the tablet as soon as possible, preferably within 12 hours, and no later than 72 hours (3 days) after you have had unprotected sex. Do not delay taking the tablet. The tablet works best the sooner you take it after having unprotected sex. It can only prevent you becoming pregnant, if you take it within 72 hours of unprotected sex.

• Postinor-1 can be taken at any time in your menstrual cycle assuming you are not already pregnant or think you may be pregnant. Swallow the tablet whole with water. Do not chew it.
• If you are using one of the medicines that may prevent Postinor-1 from working properly (see section above “Other medicines and Postinor-1”) or if you have used one of these medicines in the past 4 weeks, Postinor-1 may not work as well for you.
• If you are already using a regular method of contraception such as the contraceptive pill, you can continue to take this at your regular times.

If another unprotected intercourse takes place after the use of Postinor-1 (also if this is during the same menstrual cycle), the tablet will not be effective and there is again the risk of pregnancy.

Speak to a healthcare professional if you are concerned about any problems related to taking emergency contraception.

Postinor-1 is not recommended for children. There is only limited information available on Postinor-1 when taken by women aged 14-16 years and no information on its use in younger women or children.

While taking Postinor-1

If you vomit within 2 hours of taking the tablet you should return to your pharmacy, doctor or clinic as the tablet may not be absorbed and you will need to take an additional tablet.

Things you must do

Tell any doctor or pharmacist who is treating you that you have taken Postinor–1.

Things you must not do

Do not give Postinor-1 to anyone else.

Things to be careful of

If Postinor-1 makes you drowsy or dizzy, do not drive a car or operate machinery.

Postinor-1 contains lactose Each Postinor-1 tablet contains 142.5 mg lactose monohydrate.

If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this product.

Side effects

Tell your doctor or pharmacist as soon as possible if you do not feel well after you take Postinor-1.

All medicines have side effects. Often they are not serious but sometimes they can be. You may need medical treatment if you get some side effects.

Do not be alarmed by this list of possible side effects.

You may not experience any of them.

Ask your doctor or pharmacist to answer any questions you may have.

Common side effects are tiredness, nausea and vomiting. Some patients have also experienced stomach pain, diarrhoea, dizziness, headache, tender breasts, increased vaginal bleeding and skin reactions.

Other side effects not listed above may also occur in some patients. Tell your doctor or pharmacist if you notice anything that is making you feel unwell.

After using Postinor-1

You should see your doctor within 3 weeks of taking Postinor-1 to make sure that Postinor-1 has worked. You may experience spotting or vaginal bleeding earlier than expected.

If you do not get your period, it is more than 5 days late or is unusually light or unusually heavy, you must see your doctor, as you may be pregnant. If Postinor-1 does not work, you could be pregnant. Your doctor will order a pregnancy test. If stomach pain is severe you should see your doctor immediately as on rare occasions a tubal pregnancy could occur.

Postinor-1 is only intended as an emergency measure. If you have not already done so you should discuss with your doctor other methods of long term contraception.

You should not breast feed within three days after taking Postinor-1.

If you take too much (Overdose)

Telephone your doctor, or the Poisons Information Centre (13 11 26 in Australia) if you take too many Postinor-1 tablets, or if a child has taken Postinor-1.

Although there have been no reports of serious harmful effects from taking too many tablets at once, you may feel sick, actually be sick (vomit), or have vaginal bleeding. You should ask your pharmacist, doctor, practice nurse or family planning clinic for advice, especially if you have been sick, as the tablet may not have worked properly.

Product description:

Postinor-1 contains one blister sheet containing one flat white tablet. The tablet contains 1.5 milligrams of levonorgestrel and the following inactive ingredients: potato starch, maize starch, colloidal anhydrous silica, magnesium stearate, talc, lactose.

Storage:

Keep your tablet in the pack until it is time to take it. If you take the tablet out of the pack it will not keep well.

Keep your tablet in a cool, dry place where the temperature stays below 25°C.

Do not store Postinor-1 or any other medicine in the bathroom or near a sink.

Do not leave it in the car on hot days or on window sills.

Heat and dampness can destroy some medicines.

Keep it where children cannot reach it.

A locked cupboard at least 1½ metres above the ground is a good place to store medicines.

The expiry date is printed on the pack and the foil blister. Do not use Postinor-1 after this expiry date.

Where to go for further information

If you require further information you should contact your pharmacist, doctor or clinic.

Additional information is also available at the website: www.emergencycontraception.com.au

Supplier:

The sponsor for Postinor-1 in Australia is:

Gedeon Richter Australia Pty LtdUnit 33 & 3423 Narabang WayBelrose NSW 2085AUSTRALIA

The distributor for Postinor-1 in Australia is:

Pharmacor Pty LtdSuite 803, Level 8,Tower A, The Zenith,821 Pacific Highway,Chatswood, NSW, 2067AUSTRALIAPh: 1300 138 805www.pharmacor.com.au

The AUST R Number for Postinor-1 is 149269.

This leaflet was updated in March 2020.

Published by MIMS October 2020

BRAND INFORMATION

Brand name

Postinor-1

Active ingredient

Levonorgestrel

Schedule

S3

See related product images

Postinor-1 1.5 mg Tablets

1 Name of Medicine

Levonorgestrel.

2 Qualitative and Quantitative Composition

Postinor-1 tablet contains 1.5 mg of levonorgestrel.

Excipients with known effect.

Lactose monohydrate (see Section 4.4 Special Warnings and Precautions for Use, Excipients). For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Almost white, flat rimmed tablet of about 8 mm in diameter, with an impressed mark of "GOO" on one side.

4 Clinical Particulars

4.1 Therapeutic Indications

Postinor-1 is an oral emergency contraceptive indicated for use within 72 hours of unprotected intercourse. It should be used only as an emergency measure. Women who present for repeated courses of emergency contraception should be advised to consider long-term methods of contraception.

4.2 Dose and Method of Administration

Dosage.

One 1.5 mg tablet to be taken as soon as possible (and not later than 72 hours) after unprotected intercourse. The highest efficacy is achieved if the tablet is taken as early as possible. Therefore, treatment should not be delayed as efficacy declines with time. If the patient vomits within two hours of taking the tablet, she should return to her pharmacist, doctor or clinic where an additional tablet may be given. Postinor-1 can be used at any time during the menstrual cycle unless menstrual bleeding is overdue.

Children.

Postinor-1 is not recommended in children. Only limited data are available in young women of childbearing potential aged 14 to 16 years. No data are available about use in young women aged less than 14 years or children.

Method of administration.

For oral administration.

4.3 Contraindications

Hypersensitivity to the active substance or to any of the excipients listed (see Section 6.1 List of Excipients). Postinor-1 should not be given to pregnant women. If menstrual bleeding is overdue, if the last menstrual period was abnormal in timing or character or if pregnancy is suspected for any other reason, pregnancy should be excluded (by pregnancy testing or pelvic examination) before treatment is given. If a woman has had unprotected intercourse more than 72 hours earlier in the same menstrual cycle conception may have already occurred. Treatment with Postinor-1 following the second act of intercourse during the same menstrual cycle may therefore, be ineffective in preventing pregnancy. While the consensus is that levonorgestrel is not teratogenic, no guarantee can be given that pregnancy will result in a normal baby. Progestogen only contraceptive pills (POPs) are used as a routine method of birth control over longer periods of time, and are contraindicated in some conditions. It is not known whether these same conditions apply to the Postinor-1 regimen consisting of the emergency use of one 1.5 mg tablet. Traditionally many of the contraindications to combined hormonal contraception have been applied to progestogen only contraception. Since the contraindications largely apply to oestrogen this is inappropriate. In their medical eligibility criteria, the World Health Organisation advises that the only absolute contraindications to high dose progestogen only contraception are unexplained vaginal bleeding, current breast cancer, pregnancy or hypersensitivity to any of the ingredients of the preparation.

4.4 Special Warnings and Precautions for Use

Conditions which are regarded as relative contraindications include severe hypertension (BP > 180+/110+), diabetes mellitus with nephropathy, retinopathy, neuropathy or vascular disease, ischaemic heart disease, stroke, or a past history of breast cancer. Since exposure to levonorgestrel with Postinor-1 is brief, the risks of pregnancy in all women, including those with pre-existing medical conditions, are almost certainly greater than those associated with Postinor-1. In individual cases the risk-benefit ratio should be assessed by the practitioner in discussion with the patient. If pregnancy occurs or there are complaints of severe lower abdominal pain after treatment with levonorgestrel, the possibility of an ectopic pregnancy should be considered. The absolute risk of ectopic pregnancy is likely to be low, as levonorgestrel prevents ovulation and fertilisation. Ectopic pregnancy may continue, despite the occurrence of uterine bleeding. Therefore, levonorgestrel is not recommended for patients who are at risk of ectopic pregnancy (previous history of salpingitis or of ectopic pregnancy). Repeated administration within a menstrual cycle is not advisable. Women who present for repeated courses of emergency contraception should be advised to consider long-term methods of contraception. Emergency contraception should be taken as soon as possible after unprotected sexual intercourse or failure of a contraceptive method.

Use in hepatic impairment.

Postinor-1 is not recommended in patients with severe hepatic dysfunction.

Excipients.

Postinor-1 contains 142.5 mg lactose. This should be taken into account in women with rare hereditary problems of galactose intolerance, the total lactase deficiency or glucosegalactose malabsorption.

Regular methods of contraception.

Postinor-1 is not as effective as conventional regular methods of contraception and is suitable only as an emergency contraceptive measure. Emergency contraception does not prevent a pregnancy in every instance. If menstrual periods are delayed by more than 5 days or abnormal bleeding occurs at the expected date of menstrual periods or pregnancy is suspected for any other reason, pregnancy should be excluded.

Sexually transmitted diseases.

Levonorgestrel does not protect against sexually transmitted diseases (STDs), including HIV/AIDS.

Use in the elderly.

No data available.

Paediatric use.

Postinor-1 is not indicated for use in children. Only limited data are available in young women of child-bearing potential aged 14 to 16 years. No data are available about use in young women aged less than 14 years or in children (also see Section 4.2 Dose and Method of Administration).

Effects on laboratory tests.

No data available.

Precautions before use.

Exclude pregnancy if suspected clinically. Breast or pelvic examinations are not routinely necessary. Perform such examinations only if indicated by the patient's history. Blood pressure may be measured before prescribing Postinor-1. An elevated BP is not a contraindication to treatment but indicates the need for further investigation. No routine laboratory testing is required. Possibility of an early or late onset of the next menstrual period. Advise the practice of abstinence or careful use of a barrier method (e.g. condom, diaphragm, spermicide, cervical cap) until the onset of the next period. Follow-up should be offered 3 weeks after administration of therapy to assess the effectiveness of the method, to discuss future management if a period has not occurred, and to counsel the patient about future contraception. The use of levonorgestrel does not affect the continuation or starting of regular hormonal contraception. Women should be warned that if pregnancy occurs after treatment with Postinor-1, there is a possibility of an ectopic pregnancy.

Precautions after use.

If pregnancy occurs after treatment with Postinor-1, the possibility of an ectopic pregnancy should be considered. Vomiting, severe diarrhoea or other causes of malabsorption such as Crohn's disease, might impair the efficacy of Postinor-1. Women suffering from conditions associated with possible malabsorption should be referred for medical consultation as consideration should be given to the taking of another tablet. If the patient vomits within two hours of taking the tablet, she should return to her pharmacist, doctor or clinic where an additional tablet may be given (also see Section 4.2 Dose and Method of Administration).

4.5 Interactions with Other Medicines and Other Forms of Interactions

The metabolism of levonorgestrel can be enhanced by concomitant use of drugs which induce CYP3A4, one of the family of liver enzymes. This may reduce the effectiveness of Postinor-1 in preventing pregnancy. Concomitant use of liver enzyme inducers like efavirenz, rifampin and medicinal products for epilepsy is not recommended. Drugs suspected of having the capacity to reduce the efficacy of levonorgestrel containing medicines include barbiturates (including primidone), phenytoin, carbamazepine, herbal medicines containing Hypericum perforatum (St. John's wort), rifampicin, ritonavir, rifabutin, griseofulvin and efavirenz. Medicines containing levonorgestrel may increase the risk of cyclosporin toxicity due to possible inhibition of cyclosporin metabolism. Levonorgestrel has the ability to decrease glucose tolerance when it is used in the longer term. However, use of levonorgestrel as an emergency contraceptive is not thought to induce significant modification of carbohydrate metabolism.

4.6 Fertility, Pregnancy and Lactation

Effects on fertility.

Levonorgestrel increases the possibility of cycle disturbances which can sometimes lead to earlier or later ovulation dates. These changes can result in modified fertility dates; however there are no long term fertility data. (Category D) Postinor-1 is not to be used during an existing or suspected pregnancy. Research has found no significant effects on foetal development associated with the long-term use of contraceptive doses of combined oral steroids before pregnancy or taken inadvertently during early pregnancy. There have been an insufficient number of pregnancies in patients using levonorgestrel only oral contraceptives to rigorously evaluate the potential for developmental toxicity; however, based on the combined oral contraceptive experience, an increase in abnormalities is not expected. If taken by the mother at or after 8 weeks postconception, progestogens such as levonorgestrel can cause virilisation of the female foetus. This is a dose dependent effect. Prior to 8 weeks postconception, they have no virilising effects. There are no studies of the effect of the high levonorgestrel doses used in Postinor-1 on pregnancy and embryo/ foetal development. Progestogens do not appear to affect the quantity or quality of breast milk. However, levonorgestrel has been identified in the breast milk following oral administration to lactating women. Women should be advised not to breastfeed within 3 days after taking Postinor-1.

4.7 Effects on Ability to Drive and Use Machines

The effects of this medicine on a person's ability to drive and use machines were not assessed as part of its registration.

4.8 Adverse Effects (Undesirable Effects)

Clinical trial data.

The adverse reactions reported with an incidence of greater than 1% in the Ho and Kwan and the pivotal studies (two 750 microgram tablets taken 12 hours apart) are included in Table 1. Side effects did not result in any discontinuations in either study. No ectopic pregnancies or congenital abnormalities were reported in either study. However, such a possibility must always be considered, as there have been rare reports of ectopic pregnancies reported during postmarketing surveillance. Cutaneous reactions have also been reported from postmarketing surveillance on rare occasions. In the additional studies conducted to compare dosing with two 750 microgram tablets taken as a single dose and taking the two tablets 12 hours apart, the adverse events recorded were mostly similar to the above studies, as detailed in Table 2. One ectopic pregnancy was observed in the pivotal study and none in the supporting (Arowojolu) study. Overall, there was no indication that taking the full 1.5 mg dose at the one time resulted in an adverse event profile of greater concern than that for the regimen when the two 750 microgram tablets were taken 12 hours apart. From post-marketing surveillance the following adverse events have been reported:

Skin and subcutaneous tissue disorders.

Very rare (< 1/10,000): rash, urticaria, pruritus.

Reproductive system and breast disorders.

Very rare (< 1/10,000): pelvic pain, dysmenorrhoea.

Gastrointestinal disorders.

Very rare (< 1/10,000): abdominal pain.

General disorders and administration site conditions.

Very rare (< 1/10,000): face oedema.

Reporting suspected adverse effects.

Reporting suspected adverse reactions after registration of the medicinal product is important. It allows continued monitoring of the benefit-risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions at www.tga.gov.au/reporting-problems

4.9 Overdose

For information on the management of overdose, contact the Poisons Information Centre on 13 11 26 (Australia). Serious ill effects have not been reported following acute ingestion of large doses of oral contraceptives. Overdose may cause nausea and vomiting, and withdrawal bleeding may occur. There are no specific antidotes and treatment should be symptomatic.

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.

The precise mode of action of Postinor-1 is not known. Emergency hormonal contraception is thought to work mainly by preventing ovulation and fertilisation by altering tubal transport of sperm and/or ova. Levonorgestrel is not effective once the process of implantation has begun.

Clinical trials.

Two large controlled studies of levonorgestrel using 750 microgram tablets (two tablets taken 12 hours apart), for emergency contraception have been undertaken. The first of these is referred to as the Ho and Kwan study and the second, which included larger numbers, as the Pivotal study. Both studies compared this treatment regime to the Yuzpe regimen (ethinylestradiol 100 micrograms plus levonorgestrel 500 micrograms, repeated 12 hours later). The Ho and Kwan study was a single centre and open-label (age range 18-45 years) while the Pivotal study was multicentre, randomised and double-blind (age range 14-47 years), with both including women requiring emergency contraception resulting from no contraception used during intercourse or contraception method failure. The regimens were similar with two exceptions: The Ho and Kwan study allowed treatment to be initiated up to 48 hours post intercourse whereas the Pivotal study allowed a 72 hour gap between treatment initiation and intercourse; The treatment regimen in both studies used two tablets, the second taken 12 hours after the first. In the Pivotal study only, women in each of the two groups were provided with replacement medication to take should vomiting occur within 4 hours of either dose. The efficacy results from the efficacy population analysis from the two studies are summarised in Table 3: The relative risk of pregnancy in the Pivotal study for the Yuzpe versus levonorgestrel regimens was 2.8 with a lower one-sided 95% confidence bound of 1.53. Stratified analyses of the data showed no significant effect for age or ethnicity. For interval between intercourse and initiation of treatment, shorter intervals were associated with lower pregnancy rates. Two further studies have been conducted in order to determine whether taking two 750 microgram tablets at the same time (as a single dose) was as efficacious as taking the two tablets 12 hours apart. The pivotal study for this comparison was a double blind, randomised, double dummy multicentre study, conducted by the WHO/HRP across 10 countries. This study included women ranging in age from 14 to 52 years, and allowed for enrolment up to 120 hours after intercourse. A supporting study (Arowojolu et al, 2002) for this comparison was conducted in Nigeria at a single centre. A total of 1,118 women were assessed for efficacy in this study. The efficacy results from the data analysis for the two treatment regimens from both studies are summarised in Table 4: There was no significant difference in efficacy between the two levonorgestrel treatment groups in the pivotal study. Shorter intervals between intercourse and treatment were associated with lower pregnancy rates in both groups. The authors of the supporting study (Arowojolu et al, 2002) concluded that both treatment regimes were effective - the single two tablet dose appeared to be more effective than when the two tablets were taken 12 hours apart and that the earlier the medication is taken after unprotected intercourse, the better the efficacy. Adverse events reported in these two studies were similar for both treatment groups (see Section 4.8 Adverse Effects (Undesirable Effects)). No specific clinical trials investigating pregnancy outcome have been conducted on the single 1.5 mg tablet. Evidence for its efficacy is based on the 1.5 mg tablet and two 750 microgram tablets taken at the same time having the same pharmacokinetic profile.

Efficacy.

From earlier studies where two Postinor-1 tablets (each 750 micrograms) have been taken 12 hours apart, it has been estimated that Postinor-1 prevents 85% of expected pregnancies. Efficacy appears to decline with time after intercourse (95% within 24 hours, 85% 24-48 hours, 58% if used between 48 and 72 hours). In an additional study to compare taking the two tablets 12 hours apart versus taking a total dose of 1.5 mg after unprotected intercourse, similar rates of prevention of pregnancy were observed when taken within 72 hours. In this study, it was also observed that efficacy declined with increasing time of taking the medication after intercourse. In further studies to compare the bioavailability of the single 1.5 mg tablet to two 750 microgram tablets, it has been determined that the efficacy would be similar.

5.2 Pharmacokinetic Properties

Absorption.

A study compared the pharmacokinetics of Postinor-1 (1.5 mg levonorgestrel tablet taken as a single dose) with that of two 750 microgram tablets taken 12 hours apart. Following ingestion of one 1.5 mg tablet, maximum plasma drug levels of 18.5 nanogram/mL were found at 2 hours. Thereafter, levonorgestrel plasma levels decreased with a half-life of approximately 26 hours. In this study, the Cmax was higher for the single 1.5 mg tablet, but plasma levels over a 24 hour period were similar, as were the Tmax and half-life. In another study, a comparison of the pharmacokinetics with two 750 microgram tablets taken together (as a single dose) or 12 hours apart showed similar levels of serum levonorgestrel over a 24 hour period, and similar terminal half-lives (43.7 versus 43.3 hours). The Cmax was about 50% higher when the two tablets were taken together than when they were taken 12 hours apart (12.3 versus 7.9 nanogram/mL, p=0.03), and this occurred at 2.5 and 1.8 hours, respectively, after the (first) dose. When the bioavailability of a single 1.5 mg Postinor-1 tablet was compared to two 750 microgram tablets taken at the same time, AUC and Cmax were found to be the same with both treatments. In this study, maximum plasma drug levels of 19.1 nanogram/mL were found at 1.7 hours following the ingestion of one 1.5 mg tablet. Thereafter, levonorgestrel plasma levels decreased with a half-life of approximately 27 hours. In general, it is recognised that the pharmacokinetics of levonorgestrel can be quite variable.

Distribution.

Levonorgestrel is bound to serum albumin and sex hormone binding globulin (SHBG). Only about 1.5% of the total serum levels are present as free steroid, but 65% are specifically bound to SHBG.

Metabolism and excretion.

Levonorgestrel is not excreted in unchanged form but as metabolites. Levonorgestrel metabolites are excreted in about equal proportions with urine and faeces. The biotransformation follows the known pathways of steroid metabolism with levonorgestrel being hydroxylated in the liver and the metabolites then excreted as glucuronide conjugates. No pharmacologically active metabolites are known. The absolute bioavailability of levonorgestrel was determined to be almost 100% of the dose administered. About 0.1% of the maternal dose can be transferred via milk to the nursed infant.

5.3 Preclinical Safety Data

Genotoxicity.

No studies of the mutagenic potential of levonorgestrel have been performed.

Carcinogenicity.

No studies of the carcinogenic potential of levonorgestrel have been performed. Numerous epidemiological studies have been performed to determine the incidence of breast, endometrial, ovarian and cervical cancer in women using combination oral contraceptives. Some studies suggest that combination oral contraceptive use has been associated with an increase in the risk of cervical intraepithelial neoplasia in some populations of women but there continues to be controversy about the extent to which this finding is attributable to the confounding effects of sexual behaviour and other factors such as human papilloma virus (HPV). Evidence in the literature suggests that use of combination oral contraceptives is not associated with an increased risk of developing breast cancer in the overall population of users. However, some of these same studies have shown an increased relative risk of breast cancer in certain subgroups of combination-oral-contraceptive users, although no consistent pattern of findings has been identified. Benign hepatic adenomas have been found to be associated with the use of oral contraceptives containing levonorgestrel. Although benign, hepatic adenomas may rupture and cause death through intra-abdominal haemorrhage. The contribution of the progestin component of oral contraceptives to the development of hepatic adenomas is not known.

6 Pharmaceutical Particulars

6.1 List of Excipients

The tablet also contains the following excipients: colloidal anhydrous silica, lactose monohydrate, magnesium stearate, maize starch, potato starch, purified talc.

6.2 Incompatibilities

Incompatibilities were either not assessed or not identified as part of the registration of this medicine.

6.3 Shelf Life

3 years.

6.4 Special Precautions for Storage

Store below 25°C. Do not remove from primary pack except for immediate use.

6.5 Nature and Contents of Container

One PVC/aluminium foil blister sheet containing one tablet.

6.6 Special Precautions for Disposal

In Australia, any unused medicine or waste material should be disposed by taking to your local pharmacy.

6.7 Physicochemical Properties

Levonorgestrel is a white or almost white, odourless or almost odourless, crystalline powder. Practically insoluble in water; slightly soluble in alcohol, in acetone and in ether; soluble in chloroform; sparingly soluble in methylene chloride.

Chemical structure.

Levonorgestrel is a progestogen. The chemical name for levonorgestrel is (-)-13β-ethyl-17βhydroxy-18,19-dinor- 17α-pregn-4-en-20-yn-3-one. Its structural formula is: C21H28O2. Molecular weight: 312.45.

CAS number.

797-63-7.

7 Medicine Schedule (Poisons Standard)

Schedule 3 Pharmacist Only Medicine.

Summary Table of Changes

Date published: 01 March 2024

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