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Mestranol + norethisterone tablets


Tablets containing mestranol and norethisterone

Drugs List

  • norethisterone 1mg and mestranol 50microgram tablets
  • NORINYL-1 tablets
  • Therapeutic Indications


    Oral contraception - monophasic combined (standard dose oestrogen)



    One tablet to be taken daily at the same time (preferably evening) without interruption for 21 days, followed by a break of 7 days. Subsequent packs are started after the 7 tablet-free days.

    The first tablet of the first pack should be taken on the first day of menstruation. If menstruation has already started and the first tablet is taken up to and including day 5 of the menstrual period, in this case additional barrier contraception is required for the first 7 days.

    After childbirth (not breastfeeding) or second trimester abortion or miscarriage
    Tablet taking can start 21 to 28 days after a vaginal delivery provided that the patient is fully ambulant and there are no puerperal complications (increased risk of thrombosis if started earlier).

    If the tablets are started later than 28 days after delivery, alternative methods of contraception are required until the tablets are taken and for the first seven days of tablet-taking.

    Since the first post-partum ovulation may precede the first bleeding, another method of contraception should be used in the interval between childbirth and the first course of tablets. If unprotected intercourse has taken place during this period then pregnancy should be excluded or the woman should wait for her first menstrual period before tablet taking may commence.

    After first trimester abortion or miscarriage
    After a first trimester abortion or miscarriage, oral contraception may be started immediately in which case no additional contraceptive precautions are required.

    Changing from a combined oral contraceptive pill
    All active tablets in the old pack should be finished. The first new tablet should be taken the next day, but no later than the day after usual tablet-free (or placebo) period. No additional contraceptive precautions are required.

    Changing from a combined hormonal contraceptive vaginal ring or transdermal patch
    The first tablet should be taken on the day of removal, but no later than when the next application would have been due.

    Changing from a progestogen-only pill
    The first tablet may be taken on any day, additional contraceptive precautions should be taken for the first 7 days.
    If the tablet is taken on the first day of menstruation no additional contraception is required.

    Changing from a progestogen implant, injection or intrauterine system (IUS)
    The first tablet should be taken on the day the implant or IUS is due for removal or the next injection is due. Additional contraceptive precautions should be taken for the first 7 days.


    (See Dosage; Adult)

    Additional Dosage Information

    Special circumstances requiring additional contraception
    Missed tablets
    It is important to bear in mind that the critical time for loss of protection is when a tablet is omitted at the beginning or end of a cycle (and therefore the tablet-free interval is lengthened). A missed tablet is defined as being 12 hours or more late.

    Advise patients that missing tablets or starting the pack late may make the tablet less effective.

    Day 1 to 7
    The missed tablet should be taken as soon as remembered, even if this means taking 2 tablets at the same time. The remaining tablets in the pack should be taken at the usual time. Barrier contraception is required for the next 7 days. If intercourse took place in the preceding 7 days, the possibility of pregnancy should be considered.

    Day 8 to 14
    The missed tablet should be taken as soon as remembered, even if this means taking 2 tablets at the same time. The remaining tablets in the pack should be taken at the usual time. Provided that the tablets have been taken correctly in the 7 days preceding the missed tablet, no additional barrier contraception is required.

    Day 15 to 21
    Provided that the tablets have been taken correctly in the 7 days preceding the missed tablet, no additional barrier contraception is required as long as one of the following options is adhered to.

    1. The missed tablet should be taken as soon as remembered, even if this means taking 2 tablets at the same time. The remaining tablets in the pack should be taken at the usual time and the next pack should be started as soon as the previous pack is finished i.e. no tablet-free interval.

    2. The current pack should be discontinued and the 7 day tablet-free interval should be taken (including the day the tablet was missed), after which the next pack should be started.

    If two or more tablets are missed (i.e. more than 48 hours late) anywhere in the pack then the patient should:
    Take last missed tablet as soon as remembered, even if its means taking 2 tablets at the same time and leave any earlier missed tablets. Continue taking the rest of the pack as usual and use an extra method of contraception for the next 7 days.

    Emergency contraception may be needed.

    The next pack of tablets may be needed to be taken without a break.

    Emergency Contraception
    If unprotected sexual intercourse has taken place in the previous 7 days and two or more tablets have been missed (i.e. more than 48 hours late) in the first week of a pack, emergency contraception may be needed. Advise the patient to seek guidance from a contraception clinic, family doctor or a pharmacist.

    Diarrhoea and vomiting
    Vomiting up to 4 hours after taking a dose or severe diarrhoea can interfere with absorption and limit effectiveness. Another tablet should be taken as soon as possible. If more than 12 hours elapse from the usual time of tablet taking then the missed tablet advice should be taken. Additional precautions should therefore be used during and for 7 days after recovery. Other methods of contraception should be considered if the gastro-intestinal disorder is likely to be prolonged.


    For oral administration.


    Multiple risk factors for thromboembolic disease
    Predisposition to thromboembolic disease
    Abnormal liver function test
    Acute pancreatitis
    Breast cancer
    Breastfeeding - until weaning or 6 months post partum
    Cerebral ischaemia
    Diabetes mellitus with vascular involvement
    Endometrial hyperplasia
    Focal migraine
    Hepatic disorder
    Hepatic neoplasm
    Hepatitis with abnormal liver function
    History of acute pancreatitis with hyperlipidaemia
    History of breast cancer
    History of hepatic neoplasm
    History of hormone dependent neoplasm
    History of thromboembolic disorder
    Hormone dependent neoplasm
    Ischaemic heart disease
    Oestrogen dependent neoplasm
    Severe dyslipoproteinaemia
    Severe hypertension
    Undiagnosed gynaecological haemorrhage
    Venous thromboembolism

    Precautions and Warnings

    Family history of thromboembolic disorder
    Females over 35 years
    History of chorea during pregnancy
    Prolonged immobilisation
    Recent major surgery
    Risk factor for oestrogen-dependent neoplasm
    Tobacco smoking
    Wearing of contact lenses
    Abnormal mammography
    Atrial fibrillation
    Cardiac valvulopathy
    Cardiovascular disorder
    Crohn's disease
    Diabetes mellitus
    Epileptic disorder
    Glucose-galactose malabsorption syndrome
    Hereditary angioneurotic oedema
    History during pregnancy of pemphigoid gestationis
    History of chloasma
    History of cholelithiasis
    History of cholestatic jaundice during pregnancy
    History of haemolytic uraemic syndrome
    History of hepatic disorder
    History of migraine
    History of oligomenorrhoea
    History of pregnancy-related deterioration in otosclerosis
    History of pruritus during pregnancy
    History of secondary amenorrhoea
    History of severe depression
    History of steroid induced jaundice
    Inflammatory bowel disease
    Lactose intolerance
    Malignant neoplasm
    Multiple sclerosis
    Non focal aura migraine
    Recent trophoblastic disorder
    Renal impairment
    Severe depression
    Sickle cell disease
    Systemic lupus erythematosus

    Assess family medical history prior to commencing treatment
    Pre-treatment medical history and clinical examination
    Contains lactose
    Resume use only after 2wks full ambulation from surgery/immobilisation
    Exclude pregnancy prior to initiation of treatment
    If upper abdominal complaints/liver enlargement consider liver tumour
    Monitor blood glucose closely in patients with diabetes mellitus
    Monitor blood pressure
    Increased risk of VTE during travel involving >5hr immobilisation
    Vomiting or severe diarrhoea may impair efficacy
    May affect results of some laboratory tests
    May alter result of some lab tests-inform lab/redo 2months after OC stopped
    Discontinue 4 - 6 weeks before major surgery
    Advise patient to seek advice at first indications of pregnancy
    Discontinue at first signs of jaundice, hepatitis or whole body itching
    Discontinue at first signs of thrombophlebitis or thromboembolism
    Discontinue if conditions likely to deteriorate in pregnancy worsen
    Discontinue if depression worsens or recurs
    Discontinue if epilepsy is exacerbated
    Discontinue if headache assoc with weakness/numbness one side/part occurs
    Discontinue if headache associated with sudden dysphasia or vertigo occurs
    Discontinue if headache associated with sudden motor disturbances occurs
    Discontinue if headache associated with syncope or collapse occurs
    Discontinue if headache with sudden partial/complete vision loss occurs
    Discontinue if liver function tests become abnormal
    Discontinue if severe pain in the calf of one leg occurs
    Discontinue if sudden breathlessness (or cough with blood stained sputum)
    Discontinue if sudden pain in the chest occurs
    Discontinue if sudden, severe pain in stomach occurs
    Discontinue-first occurrence/worsening migraine/severe or frequent headache
    Advise patient grapefruit products may increase plasma level
    Advise patient concurrent St John's wort may reduce contraceptive effect
    All contraceptive pills slightly increase the risk of breast cancer
    Ensure patient is informed of risks of treatment
    Treatment does not protect against risk of sexually transmitted disease
    Women with a history of chloasma should avoid exposure to sun/UV light

    Patients should be individually assessed before commencing combined oral contraceptives and at regular intervals thereafter. Assessment should include personal and family history which should then guide physical examination. Parameters to be measured should include blood pressure, weight and body mass index (BMI) and if judged appropriate by the clinician, breast, abdominal examination, pelvic examination and cervical cytology. Specific attention should be given to conditions associated with increased risk of adverse events including migraine and cardiovascular risk factors such as obesity, smoking, hypertension, thrombophilia, hyperlipidaemia and previous venous thromboembolism.

    The use of any combined hormonal contraceptive increases the risk of venous thromboembolism (VTE) and arterial thromboembolism (ATE) compared with no use. Products that contain levonorgestrel, norgestimate or norethisterone are associated with the lowest risk of VTE. Other products may have up to twice this level of risk. The risk is greatest in the first year of use. There is also some evidence that the risk is increased when a combined hormonal contraceptive is restarted after a break in use of 4 weeks or more.

    Combined hormonal contraceptives are contraindicated in patients with multiple risk factors for VTE and/or ATE. If the patient has more than one risk factor, it is possible that the increased risk is greater than the sum of the individual factors, in this case the total risk should be considered. If the risk outweighs the benefit then a combined hormonal contraceptive should not be prescribed.

    Risk factors for venous thromboembolism
    Obesity; prolonged immobilisation, major surgery (especially to the legs or pelvis), major trauma; family history of venous thromboembolism (especially at a relatively early age); cancer; systemic lupus erythematosus; haemolytic uraemic syndrome; chronic inflammatory bowel disease (Crohn's disease or ulcerative colitis), sickle cell disease and increasing age (particularly above 35 years).

    Risk factors for arterial thromboembolism
    Increasing age (particularly above 35 years); smoking; hypertension; obesity; family history of arterial thromboembolism (especially at a relatively early age); migraine; diabetes mellitus, valvular heart disease; atrial fibrillation; dyslipoproteinaemia and systemic lupus erythematosus

    Should the patient develop symptoms of VTE or ATE, then the combined hormonal contraceptive should be discontinued.

    Breast cancer
    There is an increased risk of breast cancer with combined oral contraceptive (COC) use. Breast cancer is rare among women under 40 years of age whether or not they take COC. The most important risk factor for breast cancer in COC users is the age at which women discontinue the COC; the older the age at stopping the more breast cancers are diagnosed. Duration of use is less important and the excess risk gradually disappears during the course of the 10 years after stopping COC use such that by 10 years there appears to be no excess.

    Pregnancy and Lactation


    Contraindicated during pregnancy.

    Pregnancy must be excluded before starting treatment and the preparation should be withdrawn immediately if pregnancy occurs while taking oral contraception.

    It has been suggested by some investigations that oral contraceptives taken in early pregnancy may slightly increase the risk of foetal malformations, such as cardiovascular defects, eye and ear anomalies and increased frequency of Down's syndrome, although other studies have failed to support these findings. The possibility cannot be excluded, but it is certain that if a risk exists at all, it is very small.

    The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14 to 17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( ) or if this is unavailable at the backup site ( ).


    Contraindicated during breastfeeding.

    The use of these preparations may lead to reduction in the volume of milk produced and to a change in its composition. Very small amounts of the active substances may be excreted in the milk. Combined oral contraceptives should be avoided until weaning (or at least 6 months post partum). Oral progestogen-only pills are preferred.

    Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
    Specialist advice is available from the UK Drugs in Lactation Advisory Service at


    Advise women on the appropriate course of action if a tablet is missed during the cycle.

    Inform patients that if they experience any of the symptoms of thrombosis (pain in calf, sudden breathlessness, prolonged headache, visual disturbances, weakness) they should seek medical advice

    Women should be advised of the small increased risk of developing breast cancer before oral contraception is started.

    Advise patient that consuming grapefruit products may increase plasma level of the drug.

    Advise patients that taking St Johns Wort may reduce contraceptive efficacy.

    Advise patients to take the tablets at the same time each day (preferably in the evening).

    If unprotected sexual intercourse has taken place in the previous 7 days and two or more tablets have been missed (i.e. more than 48 hours late) in the first week of a pack, emergency contraception may be needed. Advise the patient to seek guidance from a contraception clinic, family doctor or a pharmacist.

    When additional contraceptive precautions are required, advise patients either not to have sex or to use a cap plus spermicide, or for her partner to use a condom. Rhythm methods are not advisable as the pill disrupts the usual cyclical changes associated with the natural menstrual cycle.

    Side Effects

    "Spotting" bleeds (early cycles)
    Abdominal pain
    Absence of withdrawal bleeding
    Breast enlargement
    Breast secretion
    Breast tenderness
    Cervical erosion
    Change in carbohydrate metabolism
    Change in lipid metabolism
    Change in vitamin metabolism
    Changes in cervical secretion
    Changes in libido
    Changes in vaginal secretion
    Contact lenses may irritate
    Decreased glucose tolerance
    Deep vein thrombosis (DVT)
    Disturbances of appetite
    Fluid retention
    Gastro-intestinal symptoms
    Hepatic impairment
    Hepatic tumours
    Increased risk of breast cancer
    Increased size of uterine fibroids
    Leg cramps
    Menstrual bleeding decreased
    Post medication amenorrhoea
    Pulmonary embolism
    Skin reactions
    Systemic lupus erythematosus
    Visual disturbances
    Weight changes

    Effects on Laboratory Tests

    A large number of laboratory tests may be affected by combined oral contraceptives, predominantly by the oestrogenic component. These include:
    Biochemical parameters of thyroid, hepatic, adrenal and renal function;
    Plasma levels of carrier proteins and lipid/lipoprotein fractions;
    Parameters of carbohydrate metabolism and parameters of coagulation and fibrinolysis.
    Changes generally remain within the normal laboratory range.

    Laboratory technicians should be made aware of patients who are receiving oral contraception, so that any effects on the above tests can be taken into consideration.


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Further Information

    Last Full Review Date: January 2017

    Reference Sources

    Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 3rd edition (2015) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

    Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 10th edition (2015) ed. Briggs, G., Freeman, R. Wolters Kluwer Health, Philadelphia.

    Joint Formulary Committee. British National Formulary. 72nd ed. London: BMJ Group and Pharmaceutical Press; 2016.

    Summary of Product Characteristics: Norinyl-1 tablets. Pfizer Limited. Revised August 2016

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