The dosage of isoniazid recommended by WHO and The Union is 5 mg/kg body weight daily with an acceptable range from 4 to 6 mg/kg.  The thrice-weekly dosage is 10 mg/kg body weight with an acceptable range from 8 to 12 mg/kg.

To facilitate administration of the drug in the field it has proven most practical to group patients according to pre-defined weight brackets and then give a predefined number of tablets according to this weight bracket.  The weight brackets shown above are recommended by The Union and permit a correct dosage across the entire spectrum of the body weight of tuberculosis patients.

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