Adult Dosing

Active tuberculosis

• 5 mg/kg PO qd x 6-18 months; Max: 300 mg PO qd
• Alt: 15 mg/kg PO 1-3 times wkly x 6-18 months; Max: 900 mg PO 1-3 times wkly

• Administer dose as per multiple-drug regimens and duration of therapy
• Should be given on empty stomach

Latent tuberculosis

• 5 mg/kg PO qd x 6-9 months; Max: 300 mg PO qd
• Alt: 15 mg/kg PO twice wkly x 9 months; Max: 900 mg PO twice wkly

Note:

• Should be given on empty stomach

Pediatric Dosing

Active tuberculosis

1 month-15 yrs

• 10-15 mg/kg PO qd x 6-18 months; Max: 300 mg PO qd
• Alt: 20-40 mg/kg PO twice wkly; Max: 900 mg PO twice wkly

>15 yrs

• 5 mg/kg PO qd x 6-18 months; Max: 300 mg PO qd
• Alt: 15 mg/kg PO 1-3 times wkly x 6-18 months; Max: 900 mg PO 1-3 x qwk

• Administer dose as per multiple-drug regimens and duration of therapy
• Should be given on empty stomach

Latent tuberculosis

• 10-15 mg/kg PO qd x 9 months; Max: 300 mg PO qd
• Alt: 20-40 mg/kg PO twice wkly; Max: 900 mg PO twice wkly

Note:

• Should be given on empty stomach

• Indicated with multiple concomitant antituberculosis drugs for treatment of all forms of active tuberculosis in which the organisms are susceptible
• Used alone for the treatment of latent tuberculosis infection to prevent the development of clinical tuberculosis. The following individuals or groups with clinical risk factors should be treated for latent infection following exclusion of active disease: (Note: The criterion for a positive reaction to a skin test is given in millimeters of induration for each group)
• Persons with HIV infection (5 mm) and those at risk for HIV infections whose infection status is unknown but are suspected of having HIV infection
• HIV infected individuals who are tuberculin-negative but belong to groups in which tuberculosis infection prevalence is high
• Close contacts individuals with newly diagnosed infectious tuberculosis (5 mm)
• Tuberculin-negative (<5 mm) children and adolescents who have been close contacts of infectious persons within the last 3 months
• Recent converters, as indicated by a tuberculin skin test ( 10 mm increase within a 2-year period for those <35 yrs; 15 mm increase for those 35 yrs). All infants and children younger than 4 yrs with a >10 mm skin test are included in this category
• Persons with abnormal chest-radiographs that show fibrotic lesions, probably from old healed tuberculosis
• Intravenous drug users known to be HIV seronegative (>10 mm)
• Individuals with the following medical conditions with the tuberculin skin test reaction 10 mm: silicosis; diabetes mellitus; prolonged therapy with adrenocorticosteroids; immunosuppressive therapy; some hematologic and reticuloendothelial diseases, such as leukemia or Hodgkin's disease; end-stage renal disease; clinical situations associated with substantial rapid weight loss or chronic undernutrition (including: intestinal bypass surgery for obesity, the postgastrectomy state (with or without weight loss), chronic peptic ulcer disease, chronic malabsorption syndromes, and carcinomas of the oropharynx and upper gastrointestinal tract that prevent adequate nutritional intake
• Individuals aged <35 yrs, with a tuberculin skin test reaction >10 mm and with no risk factors, are appropriate candidates for preventive therapy if they are included in any of the following high-incidence groups:
• Foreign-born persons from high-prevalence countries who have never received BCG vaccination
• Medically underserved low-income population, including high-risk racial or ethnic minority populations, especially blacks, Hispanics, and Native Americans
• Residents of facilities for long-term care such as correctional institutions, nursing homes, and mental institutions
• Children <4 yrs old with a tuberculin skin reaction of >10 mm. Persons <35 yrs with none of the above risk factors and those who belong to none of the high-incidence groups and have a tuberculin skin reaction of 15 mm induration

• Hypersensitivity to any of the ingredients of the product
• Drug-induced hepatitis
• Prior isoniazid-associated hepatic injury
• Acute liver disease
• Tyramine-containing foods
• Histamine-containing foods

• Severe and occasionally fatal hepatitis may occur or may develop even after many months of treatment with isoniazid; the risk of developing hepatitis is age related and increases with daily consumption of alcohol, chronic liver disease, and injection drug use
• Patients on therapy should be monitored and interviewed at monthly intervals. For persons 35 and older, in addition to monthly symptom reviews, hepatic enzymes (particularly AST and ALT) should be measured before initiating therapy and periodically throughout treatment
• Drug-associated hepatitis usually occurs during the first three months of treatment, and the enzyme levels usually return to normal despite continuance of drug, but in some cases progressive liver dysfunction occurs
• An increased risk of fatal hepatitis was reported among women receiving isoniazid, especially black and Hispanic women. This risk may further increase during the postpartum period. Closely monitor such patients, possibly including more frequent laboratory examinations
• Discontinuation of isoniazid should be considered, if abnormalities of liver function exceed 3-5 times the upper limit of normal
• Instruct patients to promptly report signs or symptoms related to liver damage or other adverse effects, such as unexplained anorexia, nausea, vomiting, dark urine, icterus, rash, persistent paresthesias of the hands and feet, persistent fatigue, weakness or fever of greater than 3 days duration and/or abdominal tenderness, especially right upper quadrant discomfort
• If these symptoms develop or if signs suggestive of hepatic damage are detected, isoniazid should be discontinued, since continued use of the drug in these cases have been reported to cause a more severe liver damage
• Isoniazid-associated hepatitis in tuberculosis patients should be given proper treatment with alternative drugs
• Therapy may be re-instituted, if necessary, only after the symptoms and laboratory abnormalities have cleared. Isoniazid should be restarted in very small and gradually increasing doses and should be discontinued if there is any indication of recurrent liver involvement
• Preventive treatment should be deferred in individuals with acute hepatic diseases

Renal Dose Adjustment

• Renal impairment: No dose adjustments
• Severe renal impairment: Dose adjustments not defined; caution advised

Hepatic Dose Adjustment

• Acute hepatic disease or prior isoniazid-associated hepatic injury: Contraindicated

• Severe and occasionally fatal hepatitis may occur or may develop even after many months of isoniazid treatment; this risk is age related and increases with daily consumption of alcohol, chronic liver disease, and injection drug use
• Patients on therapy should be monitored and interviewed at monthly intervals. For persons >35 yrs of age, in addition to monthly symptom reviews, hepatic enzymes (particularly AST and ALT) should be measured before initiating therapy and periodically throughout treatment
• An increased risk of fatal hepatitis associated with isoniazid therapy were reported among women. This risk may further increase during the postpartum period. Closely monitor such patients, possibly including frequent laboratory examinations
• Discontinuation of isoniazid should be considered, if abnormalities of liver function exceed 3-5 times the upper limit of normal
• Advise patients to promptly report signs or symptoms related to liver damage or other adverse effects. If these symptoms develop or if signs suggestive of hepatic damage are detected, isoniazid should be discontinued, since continued use in these cases have been reported to cause severe liver damage
• Therapy may be re-instituted, if necessary, only after the symptoms and laboratory abnormalities have cleared. Isoniazid should be restarted in very small and gradually increasing doses and should be discontinued if there is any indication of recurrent liver involvement

Cautions: Use cautiously in

• Hepatic impairment
• Severe renal impairment
• History of previous discontinuation of isoniazid
• Alcohol abuse
• Concurrent use of any chronically administered medication
• Peripheral neuropathy
• Pregnancy
• HIV seropositive patients

Pregnancy Category:C

Breastfeeding: Breastfeeding should not be discouraged in women taking isoniazid. Because of the low levels of isoniazid in breast milk and safe administration directly to infants, it is unlikely to cause adverse reactions in infants, but infants should be monitored for rare instances jaundice. Giving the maternal once-daily dose before the infant's longest sleep period will decrease the dose the infant receives. The amount of isoniazid in milk is insufficient to treat tuberculosis in the breastfed infant. This information is based upon LactMed database (available at http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT last accessed 11 March 2011). Manufacturer advises caution.

• CNS: Seizures, paresthesias, memory impairment, malaise
• NEURO: Optic neuritis and atrophy, peripheral neuropathy, toxic encephalopathy
• PSYCHIATRY: Toxic psychosis
• GI: Nausea, vomiting, epigastric discomfort, anorexia
• HEMA: Agranulocytosis, aplastic anemia, thrombocytopenia, eosinophilia, hemolytic or sideroblastic anemia
• HEPA: Severe hepatotoxicity, elevated liver transaminases, bilirubinemia, jaundice
• GU: Bilirubinuria
• METABOLIC: Pyridoxine deficiency, pellagra, hyperglycemia, metabolic acidosis, gynecomastia
• HYPERSENSITIVITY: Hypersensitivity reactions including fever, skin eruptions, lymphadenopathy, vasculitis
• MISC: Fatigue, rheumatic syndrome, lupus erythematosus-like syndrome

• Antitubercular agent; inhibits the synthesis of mycoloic acids, an essential component of the bacterial cell wall
• Metabolized in the liver; CYP450: 2C19, 3A4 inhibitor
• Excreted primarily in urine (50-70%)
• Half-life:
• Fast acetylators: 0.5-1.6 hrs
• Slow acetylators: 2-5 hrs

US Trade Name(s)

• Only generic available

US Availability

isoniazid (generic)

• TABS: 100, 300 mg
• SYRUP: 50 mg/5 mL

Canadian Trade Name(s)

• Isotamine-100
• Isotamine-300
• Isotamine

Canadian Availability

isoniazid (generic)

• TABS: 50, 100, 300 mg
• SYRUP: 10 mg/mL

Isotamine-100

• TABS: 100 mg

Isotamine-300

• TABS: 300 mg

Isotamine

• PWDR: 500 g/bottle
• SYRUP: 10 mg/mL

UK Trade Name(s)

• N/A

UK Availability

• N/A

Australian Trade Name(s)

• Only generic available

Australian Availability

isoniazid (generic)

• TABS: 100 mg

Antimicrobials

Antituberculosis Agents

Nicotinic Acid Derivatives

Infectious Disease

Antituberculosis Agents

Nicotinic Acid Derivatives

Pricing data from www.DrugStore.com in U.S.A.

• Isoniazid 50 MG/5ML SYRP [Bottle] (CAROLINA MEDICAL PRODUCTS)
  473 5ml = $77.14
  946 5ml = $146.54
• Isoniazid 300 MG TABS [Bottle] (TEVA PHARMACEUTICALS USA)
  90 mg = $21.99
  180 mg = $32.97
• Isoniazid 100 MG TABS [Bottle] (TEVA PHARMACEUTICALS USA)
  30 mg = $13.99
  90 mg = $20.97

Warning: This pricing information is subject to change at the sole discretion of DS Pharmacy. For the most current and up-to-date pricing information, please visit drugstore.com.

• Isoniazid 100 MG Oral Tablet (BARR LABORATORIES, INC.)
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• Isoniazid 100 MG Oral Tablet (Sandoz Inc)
• Isoniazid 100 MG Oral Tablet (West-ward Pharmaceutical Corp)
• Isoniazid 300 MG Oral Tablet (BARR LABORATORIES, INC.)
• Isoniazid 300 MG Oral Tablet (Blenheim Pharmacal, Inc.)
• Isoniazid 300 MG Oral Tablet (MIKART, INC.)
• Isoniazid 300 MG Oral Tablet (Sandoz Inc)
• Isoniazid 300 MG Oral Tablet (West-ward Pharmaceutical Corp)