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NEOMERCAZOLE 5

Active substance(s): CARBIMAZOLE

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SUMMARY OF PRODUCT CHARACTERISTICS

1

NAME OF THE MEDICINAL PRODUCT
NeoMercazole® 5

2

QUALITATIVE AND QUANTITATIVE COMPOSITION
Each NeoMercazole 5 tablet contains carbimazole Ph. Eur. 5mg.

3

PHARMACEUTICAL FORM
5 mg Tablet: Pink, circular biconvex tablet, imprinted with ‘Neo 5’ on the obverse
and plain on the reverse.

4.1

Therapeutic indications
NeoMercazole is an anti-thyroid agent. It is indicated in adults and children in
all conditions where reduction of thyroid function is required.
Such conditions are:
1. Hyperthyroidism.
2. Preparation for thyroidectomy in hyperthyroidism.
3. Therapy prior to and post radio-iodine treatment.

4.2

Posology and method of administration

NeoMercazole should only be administered if hyperthyroidism has been confirmed by
laboratory tests.
Posology
Older people
No special dosage regimen is required, but care should be taken to observe the
contraindications and warnings as it has been reported that the risk of a fatal outcome
to neutrophil dyscrasia may be greater in the elderly (aged 65 or over).
Paediatric population
Use in children and adolescents (3 to 17 years of age)
The usual initial daily dose is 15 mg per day adjusted according to response.
Use in children (2 years of age and under)

Safety and efficacy of carbimazole in children below 2 years of age have not been
evaluated systematically. Use of carbimazole in children below 2 years of age is
therefore not recommended.
Adults
The initial dose is in the range 20 mg to 60 mg, taken as two to three divided doses.
The dose should be titrated against thyroid function until the patient is euthyroid in
order to reduce the risk of over-treatment and resultant hypothyroidism.
Subsequent therapy may then be administered in one of two ways.
Maintenance regimen: Final dosage is usually in the range 5 mg to 15 mg per day,
which may be taken as a single daily dose. Therapy should be continued for at least
six months and up to 18 months. Serial thyroid function monitoring is recommended,
together with appropriate dosage modification in order to maintain a euthyroid state.
Blocking-replacement regimen: dosage is maintained at the initial level, i.e. 20 mg to
60 mg per day, and supplemental L-thyroxine, 50 mcg to 150 mcg per day, is
administered concomitantly, in order to prevent hypothyroidism. Therapy should be
continued for at least six months and up to 18 months. Where a single dosage of less
than 20 mg is recommended, it is intended that carbimazole 5 mg tablets should be
taken.
Method of administration
Oral

4.3 Contraindications
Hypersensitivity to the active substance or to any of the excipients listed in section
6.1.
Serious, pre-existing haematological conditions,
Severe hepatic insufficiency.
4.4
Special warnings and precautions for use
Bone marrow depression including neutropenia, eosinophilia, leucopenia and
agranulocytosis has been reported. Fatalities with carbimazole-induced
agranulocytosis have been reported.
Rare cases of pancytopenia/aplastic anaemia and isolated thrombocytopenia have also
been reported. Additionally, very rare cases of haemolytic anaemia have been
reported.
Patients should always be warned about the onset of sore throats, bruising or bleeding,
mouth ulcers, fever and malaise and should be instructed to stop the drug and to seek
medical advice immediately. In such patients, white blood cell counts should be
performed immediately, particularly where there is any clinical evidence of infection.

Following the onset of any signs and symptoms of hepatic disorder (pain in the upper
abdomen, anorexia, general pruritus) in patients, the drug should be stopped and liver
function tests performed immediately.
Early withdrawal of the drug will increase the chance of complete recovery.
NeoMercazole should be used with caution in patients with mild-moderate hepatic
insufficiency. If abnormal liver function is discovered, the treatment should be
stopped. The half-life may be prolonged due to the liver disorder.
NeoMercazole should be stopped temporarily at the time of administration of radioiodine (to avoid thyroid crisis).
Patients unable to comply with the instructions for use or who cannot be monitored
regularly should not be treated with NeoMercazole.
Regular full blood count checks should be carried out in patients who may be
confused or have a poor memory.
Precaution should be taken in patients with intrathoracic goitre, which may worsen
during initial treatment with NeoMercazole. Tracheal obstruction may occur due to
intrathoracic goitre.
The use of carbimazole in non-pregnant women of childbearing potential should be
based on individual risk/benefit assessment (see section 4.6).
There is a risk of cross-allergy between carbimazole, the active metabolite thiamazole
(methimazole) and propylthiouracil.
NeoMercazole contains lactose
Patients with rare hereditary problems of galactose intolerance, the Lapp lactase
deficiency or glucose-galactose malabsorption should not take this medicine.
NeoMercazole contains sucrose
Patients with the rare hereditary problems of fructose intolerance, glucose-galactose
malabsorption or sucrose-isomaltase insufficiency should not take this medicine.
4.5
Interaction with other medicinal products and other forms of interaction.
Little is known about interactions.
Interaction studies have not been performed in paediatric patients.
Particular care is required in case of concurrent administration of medication capable
of inducing agranulocytosis.
Since carbimazole is a vitamin K antagonist, the effect of anticoagulants could be
intensified. Additional monitoring of PT/INR should be considered, especially before
surgical procedures.

1

The serum levels of theophylline can increase and toxicity may develop if
hyperthyroidic patients are treated with antithyroid medications without reducing the
theophylline dosage.
Co-administration of prednisolone and carbimazole may result in increased clearance
of prednisolone.
Carbimazole may inhibit the metabolism of erythromycin, leading to reduced
clearance of erythromycin.
Serum digitalis levels may be increased when hyperthyroid patients on a stable
digitalis glycoside regimen become euthyroid; a reduced dosage of digitalis
glycosides may be needed.
Hyperthyroidism may cause an increased clearance of beta-adrenergic blockers with a
high extraction ratio. A dose reduction of beta blockers may be needed when a
hyperthyroid patient becomes euthyroid.
4.6
Fertility, pregnancy and lactation
Pregnancy
Carbimazole crosses the placenta but, provided the mother's dose is within the
standard range, and her thyroid status is monitored; there is no evidence of neonatal
thyroid abnormalities.
Studies have shown that the incidence of congenital malformations is greater in the
children of mothers whose hyperthyroidism has remained untreated than in those who
have been treated with carbimazole.
However, cases of congenital malformations have been observed following the use of
carbimazole or its active metabolite methimazole during pregnancy.
A causal relationship of these malformations, especially choanal atresia and aplasia
cutis congenita (congenital scalp defects), to transplacental exposure to carbimazole
and methimazole cannot be excluded.
Therefore, the use of carbimazole in non-pregnant women of childbearing potential
should be based on individual risk/benefit assessment (see section 4.4).
Cases of renal, skull, cardiovascular congenital defects, exomphalos, gastrointestinal
malformation, umbilical malformation and duodenal atresia have also been reported.
Therefore, carbimazole should be used in pregnancy only when propylthiouracil is not
suitable. If NeoMercazole is used in pregnancy the dose of NeoMercazole must be
regulated by the patient's clinical condition. The lowest dose possible should be used,
and this can often be discontinued three to four weeks before term, in order to reduce
the risk of neonatal complications.

1

PL20072/0013-0016 & PL20072/0014-0013; 20/12/2007

The blocking-replacement regimen should not be used during pregnancy since very
little thyroxine crosses the placenta in the last trimester.
Breast-feeding
NeoMercazole is secreted in breast milk and, if treatment is continued during
lactation, the patient should not continue to breast-feed her baby.

4.7

Effects on ability to drive and use machines

4.8

Not relevant.
Undesirable effects

Adverse reactions usually occur in the first eight weeks of treatment. The most
frequently occurring reactions are nausea, headache, arthralgia, mild gastric distress,
skin rashes and pruritus. These reactions are usually self-limiting and may not require
withdrawal of the drug.
Paediatric population
Frequency, type and severity of adverse reactions in children appear to be comparable
with those in adults.
Blood and lymphatic system disorders
Bone marrow depression including neutropenia, eosinophilia, leucopenia and
agranulocytosis has been reported. Fatalities with carbimazole-induced
agranulocytosis have been reported.
Rare cases of pancytopenia/aplastic anaemia and isolated thrombocytopenia have also
been reported. Additionally, very rare cases of haemolytic anaemia have been
reported.
Patients should always be warned about the onset of sore throats, bruising or bleeding,
mouth ulcers, fever and malaise and should be instructed to stop the drug and to seek
medical advice immediately. In such patients, white blood cell counts should be
performed immediately, particularly where there is any clinical evidence of infection.
Generalised lymphadenopathy.
Immune system disorders
Angioedema and multi-system hypersensitivity reactions such as cutaneous vasculitis,
liver, lung and renal effects occur.
Endocrine disorders
Insulin autoimmune syndrome (with pronounced decline in blood glucose level).
Nervous system disorders
Headache, neuritis, polyneuropathy.
Vascular disorders
Bleeding.

Gastrointestinal disorders
Nausea, mild gastrointestinal disturbance.
Loss of sense of taste has been observed.
Acute salivary gland swelling.
Hepatobiliary disorders
Hepatic disorders, including abnormal liver function tests, hepatitis, cholestatic
hepatitis, cholestatic jaundice and most commonly jaundice, have been reported; in
these cases carbimazole tablets should be withdrawn.
Skin and subcutaneous tissue disorders
Skin rashes, pruritus, urticaria. Hair loss has been occasionally reported.
Severe cutaneous hypersensitivity reactions have been reported in both adult and
paediatric patients, including Stevens-Johnson syndrome (very rare including isolated
reports: severe forms, including generalised dermatitis, have only been described in
isolated cases).
Musculoskeletal and connective tissue disorders
Isolated cases of myopathy have been reported. Patients experiencing myalgia after
the intake of carbimazole should have their creatine phosphokinase levels monitored
General disorders and administration site conditions
Fever, malaise.
Injury, poisoning and procedural complications
Bruising
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation 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
via the Yellow Card Scheme, website: www.mhra.gov.uk/yellowcard.
4.9

Overdose

Symptoms
No symptoms are likely from a single large dose.
Treatment
No specific treatment is indicated.

5.1

Pharmacodynamic properties

ATC Code: H03B B
Pharmacotherapeutic group: Sulfur-containing imidazole derivatives
Mechanism of action:

Carbimazole, a thionamide, is a pro-drug which undergoes rapid and virtually
complete metabolism to the active metabolite, thiamazole, also known as
methimazole. The method of action is believed to be inhibition of the organification
of iodide and the coupling of iodothyronine residues which in turn suppress the
synthesis of thyroid hormones.
5.2

Pharmacokinetic properties

Absorption
Carbimazole is rapidly metabolised to thiamazole. After oral ingestion, peak plasma
concentrations of thiamazole, the active moiety, occur at 1 to 2 hours.
Distribution
The total volume of distribution of thiamazole is 0.5 1/kg. Thiamazole is
concentrated in the thyroid gland. This intrathyroidal concentration of thiamazole has
the effect of prolonging its activity. However, thiamazole has a shorter half-life in
hyperthyroid patients than in normal controls and so more frequent initial doses are
required while the hyperthyroidism is active.
Biotransformation
Thiamazole is moderately bound to plasma proteins.
Carbimazole has a half-life of 5.3 to 5.4 hours. It is possible that the plasma half-life
may also be prolonged by renal or hepatic disease. See section 4.2.
Thiamazole crosses the placenta and appears in breast milk. The plasma:milk ratio
approaches unity.
Elimination
Over 90% of orally administered carbimazole is excreted in the urine as thiamazole or
its metabolites. The remainder appears in faeces. There is 10% enterohepatic
circulation.
5.3

Preclinical safety data

There are no preclinical data of relevance to the prescriber which are additional to that
already included in other sections of the Summary of Product Characteristics.
6.1

List of excipients

Lactose
Starch Maize
Gelatin
Magnesium Stearate
Sucrose
Acacia
Talc
Red Iron Oxide (E172)
Microcrystalline Cellulose (NeoMercazole 20 only).
6.2

Incompatibilities

Not applicable.

6.3

Shelf life
3 years.

6.4

Special precautions for storage
Do not store above 25°C. Store in the original container.

6.5

Nature and contents of container
NeoMercazole tablets are available in HDPE bottles with a low density polyethylene
tamper evident snap-fit closure. Each bottle contains 100 tablets.

6.6

Special precautions for disposal
No special requirements.

7

MARKETING AUTHORISATION HOLDER
Amdipharm UK Limited
Regency House
Miles Gray Road
Basildon
Essex
SS14 3AF
United Kingdom.

8

MARKETING AUTHORISATION NUMBER(S)
NeoMercazole 5: PL 20072/0013

9

DATE OF FIRST AUTHORISATION/RENEWAL OF THE
AUTHORISATION
NeoMercazole 5: 31 May 2004

10

DATE OF REVISION OF THE TEXT
30/07/2014

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Source: Medicines and Healthcare Products Regulatory Agency

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