Brand
name :NEO-MERCAZOLE (Carbimazole)
General information
Drug Code Preparation Strength
Description of the NEO-MERCAZOLE (Carbimazole)
Carbimazole, a thioamide is an ant thyroid agent. It is a prod rug
and is completely metabolized to methimazole in vivo.
Mode of Action
It is converted to methimazole which acts by inhibiting thyroid peroxidase
(hence, inhibition of iodine formation). It inhibits coupling of the
iodotyrosines; inhibits peripheral conversion of T4 to T3.
Pharmacokinetics :
It is rapidly absorbed from GIT and completely metabolized to methimazole
in the body. It is concentrated in the thyroid gland; hence even though
half-life is only 6 hours duration of action is 24 hours. This allows
once a day Dosage schedule, once patient is under therapeutic control.
And largely excreted in urine. It crosses placental barrier and is
secreted in breast milk.
Clinical Information
Indications :· Hyperthyroidism:- Primary – Graves disease.- Secondary – toxic
nodular goitre etc.· Preparation of hyperthyroid patients for
surgery.
· Combined with radio– iodine therapy for treatment of
goitre and hyperthyroidism.
Dosage
First 3 weeks: 15 mg – 6 the hourly.
4 – 8 weeks: 10 mg - 8 the hourly.
Maintenance dose: 5 – 10 mg once day.Route of Administration
Oral:
Contraindications
· Pregnancy may cause fetal goitre or cretinism and scalp defects
(aplasia cutis)
· Lactation.
· Hypeersnentivity.
Precaution / Practice Points
· Patient should be asked to report immediately if any symptoms
of agranulocytosis occur – sore throat, fever or symptoms of
hepatotoxicity – jaundice, anoreixia, pruritis etc.,
· Continuous monitoring of WBC, differential counts and liver
function test (SGOT and SGPT levels).
· Discontinue the drug if hepatic transmaminase levels are
raised 3 times above normal value.
· Use with caution in large goiters and liver disorders.
NEO-MERCAZOLE (Carbimazole) Interactions:
It may an anti vitamin K effect – therapy potentiating the effects
of oral anticoagulants.
Adverse EffectsCommon effects:
· Nausea, vomiting, gastro – intestinal disturbances. · Headache.
· Dermatological – maculoppular skin rash and pruritis.
Can new treated with antihistamines.
· Mose serious – agranulocytosis, thrombocytopenia, aplastic
anemia can also occur. It is reversible if the drug is discontinued
immediately.
Rare effects:
· Hepatotoxicity – fulminant hepatitis,
hepatic necrosis, cholestatic jaundice.
· Hypersensitivity reactions like drug fever,
lupus like syndrome, arthralgia , vasculitis,
lymphadenopathy and interstitial nephritis.
Drug Toxicity
· Acute – nausea, vomiting, epigastric distress, headache,
fever, joint pain, pruritis, edema, exfoliative dermatitis and nephritis
may occur.
· Pancytopenia manifest in hours to days.
Treatment of Toxicity
· Maintenance of airway, ventilation support.
· Monitor vital signs, blood gases, electrolytes and bone marrow
function.
· Symptomatic and supportive treatment.
Storage :
Protect from light.
