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Isoniazid / Pyrazinamide / Rifampin Dosage

Applies to the following strength(s): 50 mg-300 mg-120 mg

The information at Drugs.com is not a substitute for medical advice. Always consult your doctor or pharmacist.

Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Tuberculosis - Active

Dosing Based on Patient Weight:
Isoniazid/pyrazinamide/rifampin 50 mg-300 mg pyrazinamide-120 mg oral tablet:
-44 kg or less: 4 tablets (200 mg isoniazid, 1200 mg pyrazinamide, and 480 mg rifampin total dose) orally once a day.
-45 to 54 kg: 5 tablets (250 mg isoniazid, 1500 mg pyrazinamide, and 600 mg rifampin total dose) orally once a day.
-55 kg or more: 6 tablets (300 mg isoniazid, 1800 mg pyrazinamide, and 720 mg rifampin total dose) orally once a day.

Duration of Therapy: 2 months (initial treatment phase)

Comments:
-This drug should be taken on an empty stomach at least 1 hour before or 2 hours after a meal with a full glass of water.
-This drug should be taken at least 1 hour before the ingestion of antacids.
-The Advisory Council for the Elimination of Tuberculosis, the American Thoracic Society, and the US CDC recommend that either streptomycin or ethambutol be added as a fourth drug in the treatment regimen, unless the likelihood of isoniazid or rifampin resistance is very low.
-Concomitant administration of pyridoxine (Vitamin B6) is recommended in the malnourished and in those predisposed to neuropathy (e.g., alcoholics and diabetics).

Use: Indicated in the Initial Phase of the Short-Course Treatment of Pulmonary Tuberculosis

Usual Pediatric Dose for Tuberculosis - Active

Age 14 Years and Younger:
-The ratio of isoniazid, pyrazinamide, and rifampin in this combination tablet may not be appropriate; for example, isoniazid mg/kg doses are typically higher in children than in adults.

Age 15 Years and Older:
Dosing Based on Patient Weight:
Isoniazid/pyrazinamide/rifampin 50 mg-300 mg pyrazinamide-120 mg oral tablet:
-44 kg or less: 4 tablets (200 mg isoniazid, 1200 mg pyrazinamide, and 480 mg rifampin total dose) orally once a day.
-45 to 54 kg: 5 tablets (250 mg isoniazid, 1500 mg pyrazinamide, and 600 mg rifampin total dose) orally once a day.
-55 kg or more: 6 tablets (300 mg isoniazid, 1800 mg pyrazinamide, and 720 mg rifampin total dose) orally once a day.

Duration of Therapy: 2 months (initial treatment phase)

Comments:
-This drug should be taken on an empty stomach at least 1 hour before or 2 hours after a meal with a full glass of water.
-This drug should be taken at least 1 hour before the ingestion of antacids.
-The Advisory Council for the Elimination of Tuberculosis, the American Thoracic Society, and the US CDC recommend that either streptomycin or ethambutol be added as a fourth drug in the treatment regimen, unless the likelihood of isoniazid or rifampin resistance is very low.
-Concomitant administration of pyridoxine (Vitamin B6) is recommended in adolescents, the malnourished, and in those predisposed to neuropathy (e.g., alcoholics and diabetics).

Use: Indicated in the Initial Phase of the Short-Course Treatment of Pulmonary Tuberculosis

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

-Impaired Liver Function: Use with caution

-Severe Liver Damage or Acute Liver Disease of Any Etiology: Contraindicated (due to isoniazid component)

Precautions

US BOXED WARNING:
-Severe and sometimes fatal hepatitis associated with isoniazid therapy may occur and may develop even after many months of treatment.
-Precise fatality rate data is not available, but there were 8 deaths among 174 hepatitis cases in a U.S. Public Health Service Surveillance Study of 13,838 persons taking isoniazid.
-The risk of developing hepatitis is increased with daily consumption of alcohol; and in general, the incidence of hepatitis increases with age: 0 per 1,000 under 20 years of age, 3 per 1,000 in the 20 to 34 age group, 12 per 1,000 in the 35 to 49 age group, and 23 per 1,000 in the 50 to 64 year age group. There is a slight decrease in the over 65 years of age group: 8 per 1,000 hepatitis cases.
-Serum transaminase concentration becomes elevated in about 10% to 20% of patients, usually during the first few months of therapy but it can occur at any time.
-Enzyme levels often return to normal despite continuance of drug, but cases of progressive liver dysfunction have occurred.
-Patients given isoniazid should be carefully monitored and interviewed at monthly intervals; patients should immediately report if they experience any of the prodromal hepatitis symptoms (e.g., fatigue, weakness, malaise, anorexia, nausea, vomiting).
-This drug should be promptly discontinued if symptoms/signs of hepatic damage are detected as isoniazid has been reported to cause a more severe form of liver damage.
-If this drug is discontinued, patients with tuberculosis should be given appropriate treatment with alternative drugs.
-If isoniazid must be reinstated, treatment should be resumed only after symptoms and laboratory abnormalities have cleared.
-This drug should be restarted in very small and gradually increasing doses and should be immediately withdrawn if there is any indication of recurrent liver involvement.
-Treatment should be deferred in persons with acute hepatic diseases.

Safety and efficacy have not been established in patients younger than 15 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration Advice:
-Prior to initiation of therapy, appropriate specimens should be collected for identification of the infecting organisms and for in vitro susceptibility tests; the need for a fourth drug (i.e., streptomycin or ethambutol) should be reassessed when the results of susceptibility testing are known.
-If community rates of isoniazid resistance are currently less than 4%, an initial treatment regimen with less than 4 drugs may be considered.

General:
-Following the initial phase, treatment should be continued with rifampin and isoniazid (e.g., Rifamate) for at least 4 months; treatment should be longer if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV positive.

Monitoring:
-Baseline measurements of hepatic enzymes, bilirubin, serum creatinine, CBC, platelet count (or estimate), and serum uric acid.
-Follow up testing (including laboratory testing) for all patients with abnormal measurements.
-Ophthalmologic examinations (including ophthalmoscopy) before treatment initiation and periodically thereafter.
-Patients should be seen at least monthly during treatment and should be specifically questioned about symptoms associated with adverse reactions.

Patient Advice:
-Notify your healthcare provider immediately if you experience any of the following: fever, loss of appetite, malaise, nausea, vomiting, darkened urine, yellowing discoloration of the skin and eyes, pain or swelling of the joints.
-Do not drink alcohol and do not eat foods containing tyramine (such as cheese and red wine) or histamine (such as skipjack, tuna, and other tropical fish) while taking this drug.
-During treatment, your urine, sweat, sputum, and tears may appear reddish in color and soft contact lenses may be permanently stained due to the rifampin component of this drug.
-Complete the full course of therapy; do not miss any doses.
-This drug may cause side effects such as vertigo and psychotic reactions that can affect your ability to perform certain activities; avoid driving and activities such as operating machinery until you know how this drug affects you.

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