Oral Adjunct to radio-iodine therapy, Hyperthyroidism, Preparation for thyroidectomy
Adult: Initially, 15-60 mg daily in 2-3 divided doses, reduced gradually once euthyroidism is achieved. Maintenance: 5-15 mg daily (may be taken as a single dose). Blocking replacement regimen: Initially, 20-60 mg in 2-3 divided doses in combination with levothyroxine. Treatment duration: 6-18 months. Child: 3-17 years Initially, 15 mg daily adjusted according to response.
May be taken with or without food. Take consistently w/ or w/o meals.
Serious, pre-existing haematological conditions. History of acute pancreatitis. Severe hepatic impairment.
Patient with intrathoracic goitre, any degree of tracheal obstruction. Stop carbimazole temporarily at the time of radio-iodine administration. Mild to moderate hepatic impairment. Children. Pregnancy and lactation.
Significant: Bone marrow depression (e.g. neutropenia, eosinophilia, leucopenia), acute pancreatitis. Blood and lymphatic system disorders: Rarely, pancytopenia, aplastic anaemia, haemolytic anaemia, thrombocytopenia. Endocrine disorders: Insulin autoimmune syndrome. Gastrointestinal disorders: Nausea, mild gastrointestinal disturbance, loss of sense of taste, acute salivary gland swelling. General disorders and administration site conditions: Fever, malaise. Hepatobiliary disorders: Abnormal LFT, jaundice, hepatitis, cholestatic hepatitis, cholestatic jaundice. Immune system disorders: Angioedema, hypersensitivity reactions (e.g. cutaneous vasculitis, liver, lung and renal effects). Musculoskeletal and connective tissue disorders: Arthralgia. Nervous system disorders: Headache, neuritis, polyneuropathy. Skin and subcutaneous tissue disorders: Rash, pruritus, urticaria, hair loss. Rarely, Stevens-Johnson syndrome. Vascular disorders: Bleeding. Potentially Fatal: Agranulocytosis.
Perform confirmatory test for hyperthyroidism prior to initiation of therapy. Perform regular FBC checks in patients who may be confused or have poor memory. Monitor for possible symptoms of agranulocytosis (e.g. sore throat, bruising or bleeding, mouth ulcers, fever, malaise).
May have cross-sensitivity with propylthiouracil (PTU) or thiamazole. May enhance the effect of anticoagulants. May increase the serum levels of theophylline which may result in toxicity. May increase the clearance of prednisolone. May reduce the clearance of erythromycin. Hyperparathyroid patients who become euthyroid may have increased serum concentration of digitalis and increased clearance of β-blockers.
Description: Carbimazole is completely metabolised to thiamazole which is responsible for its antithyroid action. It blocks the production of thyroid hormones through inhibition of the organification of iodide and the coupling of iodothyronine residues. Pharmacokinetics: Absorption: Rapidly absorbed from the gastrointestinal tract. Time to peak plasma concentration: Approx 1-2 hours (as thiamazole). Distribution: Concentrated in the thyroid gland (as thiamazole). Crosses the placenta and enters breast milk (as thiamazole). Volume of distribution: 0.5 L/kg. Plasma protein binding: Moderately bound (as thiamazole). Metabolism: Rapidly and completely metabolised to thiamazole. Excretion: Via urine (approx >90%, as thiamazole or its metabolites). Elimination half-life: Approx 5.3-5.4 hours.
H03BB01 - carbimazole ; Belongs to the class of sulfur-containing imidazole derivative agents. Used in the management of thyroid diseases.
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