Carbizol 5

Indications

Carbizol is recommended for managing hyperthyroidism, thyrotoxicosis (including thyroid storm), and as preparation for thyroidectomy. Additionally, Carbizol may be used alongside radioactive ablative therapy.

Pharmacology

Carbizol, an anti-thyroid substance, hinders the formation of thyroid hormone. It diminishes the absorption and concentration of inorganic iodine by the thyroid gland, primarily reducing the production of di-iodotyrosine and thyroxine. Rapidly absorbed by the gastrointestinal tract, Carbizol is extensively distributed throughout the body. It undergoes complete metabolism to methimazole, the active metabolite responsible for its clinical effects. Carbizol readily crosses the placental barrier and reaches high levels in lactating mothers’ milk.

Dosage & Administration

• Initial dose: 20-60 mg, divided into 2-3 doses daily until euthyroidism is achieved. Daily dosage should be divided.
• Maintenance regimen: Gradually reduce the dose to maintain euthyroid status, typically within the range of 5-15 mg/day, usually taken once daily.
• Neonates & Children under 12 years: Initial dose is typically 250 mcg/kg/day in divided doses.
• Duration of treatment: 18 to 24 months.

Interaction

Carbizol may interact unfavorably with other medications. Excessive iodine may reduce Carbizol’s efficacy, necessitating dosage adjustments or prolonged therapy with antithyroid agents. As the patient’s thyroid and metabolic status normalizes, the response to oral anticoagulants may decrease; however, in cases of thioamide-induced hypoprothrombinemia, anticoagulant effects may intensify. Serum concentrations of digoxin and digitoxin may rise as the patient’s thyroid function improves, potentially requiring dosage adjustments.

Contraindications

Avoid Carbizol if there’s a history of hypersensitivity to carbimazole or other thiourea antithyroid agents.

Side Effects

Potential side effects include rash, itching, skin pigmentation, tingling sensations, urticaria, headache, joint pain, gastrointestinal disturbances (such as nausea, vomiting, and gastric discomfort), and abnormal hair loss. Rarely, drug fever, lupus-like syndrome, vasculitis, nephritis, hepatic disorders (most commonly jaundice), and taste disturbances have been reported following Carbizol therapy.

Pregnancy & Lactation

Carbizol may be administered during pregnancy to manage thyrotoxicosis, but the smallest effective dose should be used to minimize fetal risks. It crosses the placenta and is excreted in breast milk, potentially causing fetal or neonatal hypothyroidism and goiter.

Precautions & Warnings

Exercise caution or avoid Carbizol administration if there’s any degree of tracheal obstruction, as high doses may lead to thyroid enlargement and exacerbate obstructive symptoms.

Overdose Effects

Overdose or accidental poisoning may result in hypothyroidism and goiter. If blood dyscrasias occur, discontinue the drug immediately. Treatment is primarily symptomatic and supportive.

Therapeutic Class

Anti-thyroid drugs.

Storage Conditions

Store below 25°C.