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FIRST-LINE MEDICATIONS FOR TUBERCULOSIS
Isoniazid (INH)
Description
- Isoniazid is bactericidal.
- It inhibits the synthesis of mycolic acids and acts to kill actively growing organisms in the extracellular environment.
- It inhibits the growth of dormant organisms in the macrophages and caseating granulomas.
- It is active only during cell division and is used in combination with other antitubercular medications.
Contraindications and cautions
- Isoniazid is contraindicated in clients with hypersensitivity or with acute liver disease.
- Use with caution in clients with chronic liver disease, alcoholism, or renal impairment.
- Use with caution in clients taking nicotinic acid (niacin).
- Use with caution in clients taking hepatotoxic medications because the risk for hepatotoxicity increases.
- Alcohol increases the risk of hepatotoxicity.
- Isoniazid may increase the risk of toxicity of carbamazepine (Tegretol) and phenytoin (Dilantin).
- Isoniazid may decrease ketoconazole (Nizoral) concentrations.
Side effects
- Hypersensitivity reactions
- Peripheral neuritis
- Neurotoxicity
- Hepatotoxicity; increased liver function test levels
- Pyridoxine (vitamin B6) deficiency
- Irritation at injection site with intramuscular administration
- Nausea and vomiting
- Dry mouth
- Dizziness
- Hyperglycemia
- Vision changes
- Hepatitis
Interventions
- Assess for hypersensitivity.
- Assess for hepatic dysfunction.
- Assess for sensitivity to nicotinic acid.
- Monitor liver function test results.
- Monitor for signs of hepatitis, such as anorexia, nausea, vomiting, weakness, fatigue, dark urine, or jaundice; if these symptoms occur, withhold the medication and notify the physician.
- Monitor for tingling, numbness, or burning of the extremities.
- Assess mental status.
- Monitor for visual changes, and notify the physician if they occur.
- Assess for dizziness and initiate safety precautions.
- Monitor complete blood count (CBC) and blood glucose levels.
- Administer isoniazid 1 hour before or 2 hours after a meal because food may delay absorption.
- Administer isoniazid at least 1 hour before antacids, especially those antacids that contain aluminum.
- Administer pyridoxine as prescribed to reduce the risk of neurotoxicity.
