Consumer medicine information

Postrelle-1

Levonorgestrel

BRAND INFORMATION

Brand name

Postrelle-1

Active ingredient

Levonorgestrel

Schedule

What is in this leaflet

This leaflet answers some common questions about Postrelle-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 Postrelle-1 against the benefits they expect it will have for you.

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

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

What Postrelle-1 is used for

Postrelle-1 is an emergency contraceptive only. Postrelle-1 is not intended as a regular method of contraception.

It contains the active ingredient levonorgestrel.

It is used to prevent pregnancy when taken within 72 hours of unprotected intercourse. It is estimated that Postrelle-1 will prevent 85% of expected pregnancies. The sooner that you take Postrelle-1 after unprotected intercourse, the more likely it is that the medicine will work.

Postrelle-1 is thought to work by:

stopping your ovaries from releasing an egg
preventing sperm from fertilising any eggs you may have already released
stopping a fertilised egg from attaching itself to your womb lining.

Therefore, Postrelle-1 stops a pregnancy before it is established. It does not work if you are already pregnant.

Postrelle-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 Postrelle-1.

This medicine is not addictive.

Before you take Postrelle-1

When you must not take it

Do not take Postrelle-1 if:

you are allergic to any medicine containing levonorgestrel, or any of the ingredients listed at the end of this leaflet
you are pregnant or think you may be 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
the tablets do not look quite right

Some of the symptoms of an allergic reaction may include

shortness of breath
wheezing or difficulty breathing
swelling of the face, lips, tongue or other parts of the body
rash, itching or hives on the skin

Do not take this medicine after the expiry date printed on the pack or if the packaging is torn or shows signs of tampering. If it has expired or is damaged, return it to your pharmacist for disposal.

If you are not sure whether you should start taking this medicine, talk to your doctor.

Before you start to take it

Tell your doctor if you have allergies to any other medicines, foods, preservatives or dyes.

Before you start treatment with Postrelle-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 breast feeding (see "After taking Postrelle-1")
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

Tell your doctor if you have or have had any of the following medical conditions:

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
you have severe liver disease.

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

you have a disease of your gastro-intestinal tract (such as Crohn's disease) that interferes with the digestion and absorption of your food and medicines
you are vomiting or have severe diarrhoea.

If these conditions apply to you your doctor may recommend a higher dose.

If you have not told your doctor about any of the above, tell him/her before you start taking Postrelle-1.

Taking other medicines

Tell your doctor or pharmacist if you are taking any other medicines, including any that you get without a prescription from a pharmacy, supermarket or health food shop.

Some medicines and Postrelle-1 may interfere with each other.

These include:

medicines used to treat epilepsy (for example, barbiturates, primidone, phenytoin, and carbamazepine).
medicines used to prevent organ transplant rejection (ciclosporin).
medicines used to treat tuberculosis (for example, rifampicin, rifabutin).
medicines used to treat HIV infection (ritonavir, efavirenz).
a medicine used to treat fungal infections (griseofulvin).
herbal remedies containing St John's Wort (Hypericum perforatum).

These medicines may be affected by Postrelle-1 or may affect how well it works.

Your doctor and pharmacist have more information on medicines to be careful with or avoid while taking this medicine.

How to take Postrelle-1

Take 1 tablet as a single dose as soon as possible after unprotected intercourse and no later than 72 hours (3 days) after intercourse. The sooner that you take the tablet, the more effective the treatment is likely to be and the more likely that an unexpected pregnancy will be prevented. It is best to take it immediately after you receive it.

Swallow the tablet whole with a full glass of water.

If you are already using a regular method of contraception such as the contraceptive pill, you can continue to take this at your regular time.

Your doctor or pharmacist should advise you to use a barrier contraception method until your next period.

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

You should only take Postrelle-1 in emergencies and not as a regular method of contraception. If Postrelle-1 is used more than once in a menstrual cycle it is more likely to upset your menstrual cycle.

Follow all directions given to you by your doctor and pharmacist carefully. They may differ from the information contained in this leaflet.

If you do not understand the instructions on the box, ask your doctor or pharmacist for help.

If you take too much (overdose)

Immediately telephone your doctor or the Poisons Information Centre (Australia: phone 13 11 26) for advice, or go to Accident and Emergency at the nearest hospital, if you think that you or anyone else may have taken too much Postrelle-1 or if a child has taken Postrelle-1. Do this even if there are no signs of discomfort or poisoning.

Although there have been no reports of serious harmful effects from taking too many tablets at once, you may feel sick or have vaginal bleeding.

While you are taking Postrelle-1

If you vomit within 2 hours of taking the tablet you should return to your pharmacy, doctor or clinic. You will need to take an additional tablet as the first one may not have been absorbed completely.

Things you must do

Always follow your doctor's or pharmacist's instructions carefully.

Your doctor will be happy to discuss any questions you may have with your medication.

Tell any other doctors, dentists, and pharmacists who are treating you that you have taken Postrelle-1.

Things you must not do

Do not give Postrelle-1 to anyone else.

Things to be careful of

Be careful driving or operating machinery until you know how Postrelle-1 affects you.

This medicine may cause dizziness or light-headedness in some people. Make sure you know how you react to Postrelle-1 before you drive a car, operate machinery or do anything else that could be dangerous.

Side effects

Tell your doctor or pharmacist as soon as possible if you do not feel well while you are taking Postrelle-1.

All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical attention if you get some of the side effects.

Do not be alarmed by the following list of side effects. You may not experience any of them.

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

Tell your doctor or pharmacist if you notice any of the following and they worry you:

tiredness
nausea
vomiting
stomach pain
diarrhoea
dizziness
headache
tender breasts
increased vaginal bleeding, irregular bleeding or spotting. Most women will have a normal period at the expected time, but some may have their period later or earlier than normal. If your period is more than 5 days late or is unusually light or unusually heavy, or especially painful, you should contact your doctor or pharmacist as soon as possible.
skin reactions

The above list includes the more common side effects of your medicine. They are usually mild and short-lived but may require medical attention.

If any of the following happen, tell your doctor immediately or go to Accident and Emergency at your nearest hospital:

swelling of the face, lips, mouth or throat which may cause difficulty in swallowing or breathing.

These are very serious side effects. You may need urgent medical attention or hospitalisation. All of these side effects are very rare.

Tell your doctor if you notice anything else that is making you feel unwell. Other side effects not listed above may occur in some people.

Do not hesitate to report any other side effects to your doctor or pharmacist.

After taking Postrelle-1

After taking Postrelle-1, you should use other contraceptive methods if you want to have sex. Postrelle-1 won't prevent pregnancy from further unprotected sex. Your doctor or pharmacist should advise you to use a barrier contraception method until your next period.

You should see your doctor within 3 weeks of taking Postrelle-1. You may experience spotting or vaginal bleeding earlier than expected.

You must see your doctor if you do not get your period within 3 weeks of taking Postrelle-1 or your period is unusually light or unusually heavy. If Postrelle-1 does not work, you could be pregnant. Your doctor will order a pregnancy test.

If you continue to use the contraceptive pill and you do not have a bleed in your pill-free week or while you are taking the non-hormonal tablets, you could be pregnant. Your doctor will order a pregnancy test.

You should see your doctor if you do become pregnant even after taking this medicine. There is no evidence that Postrelle-1 will harm a baby that develops in your uterus/womb, but your doctor may want to check for an ectopic pregnancy (where the baby develops somewhere outside the womb).

You must see your doctor immediately if you experience severe stomach pain. On rare occasions an ectopic or tubal pregnancy could occur. This is especially important if you have previously had an ectopic pregnancy, fallopian tube surgery or pelvic inflammatory disease.

You should discuss with your doctor other methods of long term contraception. Postrelle-1 is only intended as an emergency measure. Discuss with your doctor other methods of long term contraception which are more effective in preventing you from getting pregnant.

You should not breast feed within three days after taking Postrelle-1. Small amounts of levonorgestrel may appear in your breast milk.

Storage

Keep your tablet in the original pack until you need 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 Postrelle-1 or any other medicine in the bathroom or near a sink. Do not leave it on a window sill or in the car. Heat and dampness can destroy some medicines.

Keep it where children cannot reach it. A locked cupboard at least one-and-a-half metres above the ground is a good place to store medicines.

Do not take Postrelle-1 after the expiry date. The expiry date is printed on the pack and the blister foil.

Disposal

Return any unused or out of date medicine to your pharmacist.

Product description

What it looks like

Postrelle-1: Round, white to off-white, uncoated flat tablet debossed '145' on one side and other side plain. Available in blister packs containing 1 tablet.

Ingredients

Postrelle-1 contains 1.5 mg of levonorgestrel as the active ingredient.

It also contains the following inactive ingredients:

povidone
lactose monohydrate
maize starch
magnesium stearate
silicon dioxide

This medicine does not contain sucrose or gluten. This medicine contains sugars (as lactose).

Supplier

Postrelle-1 is supplied in Australia by:

Alphapharm Pty Ltd
Level 1, 30 The Bond
30 - 34 Hickson Road
Millers Point NSW 2000
www.mylan.com.au

Australian registration number:

Postrelle-1: AUST R 221973

This leaflet was prepared in 14 February 2020

Postrelle-1_cmi\Sep19/00

Published by MIMS April 2020

BRAND INFORMATION

Brand name

Postrelle-1

Active ingredient

Levonorgestrel

Schedule

1 Name of Medicine

Levonorgestrel.

2 Qualitative and Quantitative Composition

Each Postrelle-1 tablet contains 1.5 milligrams of levonorgestrel.
Postrelle-1 also contains sugars (as lactose). For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Postrelle-1 tablets.

Round, white to off-white, uncoated flat tablets debossed '145' on one side and other side plain.

4 Clinical Particulars

4.1 Therapeutic Indications

Postrelle-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

For oral administration.
One 1.5 milligram 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.
Postrelle-1 can be used at any time during the menstrual cycle unless menstrual bleeding is overdue.

Children.

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

4.3 Contraindications

Postrelle-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 Postrelle-1 following the second act of intercourse 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 Postrelle-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 estrogen 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 Postrelle-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 Postrelle-1. In individual cases the risk-benefit ratio should be assessed by the practitioner in discussion with the patient.
Postrelle-1 is not as effective as conventional regular methods of contraception and is suitable only as an emergency measure. Women who present for repeated courses of emergency contraception should be advised to consider a long-term method of contraception.
Emergency contraception does not protect against sexually transmitted infections.

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 Postrelle-1. An elevated BP is not a contraindication to treatment but indicates the need for further investigation.
No routine laboratory testing is required.
Explain the importance of follow-up and the possibility of an early or late onset of the next menstrual period to the patient. Advise the practice of abstinence or careful use of a barrier method 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.
Women should be warned that if pregnancy occurs after treatment with Postrelle-1, there is a possibility of an ectopic pregnancy.

Precautions after use.

If pregnancy occurs after treatment with Postrelle-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 Postrelle-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).

Use in hepatic impairment.

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

Use in the elderly.

No data available.

Paediatric use.

Postrelle-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 is 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.

4.5 Interactions with Other Medicines and Other Forms of Interactions

The metabolism of levonorgestrel can be enhanced by concomitant use of medicines which induce CYP3A4, one of the families of liver enzymes. This may reduce the effectiveness of Postrelle-1 in preventing pregnancy.
Medicines suspected of having the capacity to reduce the efficacy of levonorgestrel containing medications include barbiturates (including primidone), phenytoin, carbamazepine, herbal medicines containing Hypericum perforatum (St John's Wort), rifampicin, ritonavir, rifabutin, griseofulvin and efavirenz.
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.

No data available.
(Category D)
Postrelle-1 is not to be used during an existing or suspected pregnancy. Research has found no significant effects on fetal 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 post-conception, progestogens such as levonorgestrel can cause virilisation of the female fetus. This is a dose dependent effect. Prior to 8 weeks post-conception, they have no virilising effects. There are no studies of the effect of the high levonorgestrel doses used in Postrelle-1 on pregnancy and embryo/fetal 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 breast-feed within 3 days after taking Postrelle-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 events 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 post-marketing surveillance. Cutaneous reactions have also been reported from post-marketing 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 milligram 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.

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

Serious ill effects have not been reported following acute ingestion of large doses of oral contraceptives. Overdose may cause nausea, and withdrawal bleeding may occur. There are no specific antidotes and treatment should be symptomatic.
As strategies for the management of overdose are continually evolving, it is advisable to contact the Poisons Information Centre to determine the latest recommendations for the management of an overdose.
For information on the management of overdose, contact the Poisons Information Centre on 13 11 26 (Australia).

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.

Postrelle-1 is an emergency oral contraceptive tablet containing the synthetic progestogen, levonorgestrel.
The precise mode of action of levonorgestrel 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. It may also cause endometrial changes that discourage implantation.

Clinical trials.

Efficacy.

From earlier studies where two levonorgestrel tablets (each 750 micrograms) have been taken 12 hours apart, it has been estimated that levonorgestrel 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.
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 multi-centre, 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 four 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 intervals 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 1118 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.

5.2 Pharmacokinetic Properties

Absorption.

A study compared the pharmacokinetics of a 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 C_max was higher for the single 1.5 mg tablet, but plasma levels over a 24 hour period were similar, as were the T_max 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 C_max 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 levonorgestrel tablet was compared to two 750 microgram tablets taken at the same time, AUC and C_max 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.
The absolute bioavailability of levonorgestrel was determined to be almost 100% of the dose administered.

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 in 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.
About 0.1% of the maternal dose can be transferred via milk to the breast-fed 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

Povidone, lactose monohydrate, maize starch, magnesium stearate and silicon dioxide.

6.2 Incompatibilities

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

6.3 Shelf Life

In Australia, information on the shelf life can be found on the public summary of the Australian Register of Therapeutic Goods (ARTG). The expiry date can be found on the packaging.

6.4 Special Precautions for Storage

Store below 25°C. Do not remove from the primary pack except immediately before use.

6.5 Nature and Contents of Container

Postrelle-1 is supplied in blister packs (PVC/PVDC/Aluminium) containing 1 tablet.

6.6 Special Precautions for Disposal

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

6.7 Physicochemical Properties

Chemical name: (-)-13β- ethyl-17β-hydroxy-18,19-dinor-17α-pregn-4-en-20-yn-3-one.
Molecular formula: C₂₁H₂₈O₂.
Molecular weight: 312.45.
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.

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Postrelle-1

Levonorgestrel

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BRAND INFORMATION

Postrelle-1 1.5 mg Tablets