Tuberculosis - Pharmacology

Tuberculosis is caused by acid-fast bacillus Mycobacterium tuberculosis. It is a major health problem and kills more than any other infectious disease. One and one-half billion people have TB. There are 8 million new cases each year. The incidence had decreased in the United States but increased again in the 1980s. This has been attributed in part to the numbers of persons with AIDS which compromises the immune system.

First-line drugs used to treat tuberculosis are

  • Isoniazid (INH, Nydrazid, Laniazid) PO/IM: 5-10 mg/kg/d in a single
    dose; max: 300 mg/d; Prophylaxis: 300 mg/d
    • Pregnancy Category: C; PB: 10%; t1⁄2: 104 h
    • Side effects: drowsiness, tremors, rash, blurred vision, photosensitivity;
    • Adverse reactions: psychotic behavior, peripheral neuropathy, vitamin B6 deficiency
    • Life threatening: blood dyscrasias, thrombocytopenia, seizures, agranulocytosis, hepatotoxicity

Tuberculosis

  • Ethambutol HCL (Myambutol) PO: 15 mg/kg as a single dose; retreatment
    PO: 25 mg/kg as a single dose for 2 mo; then decrease to 15 mg/kg/d
    • Pregnancy category: C; PB:10-20%; t1⁄2: 3-4 h (8 h with renal dysfunction)
  • Pyrazinamide (Tebrazid): PO: 20-35 mg/kg/d in 3–4 divided doses; max:
    3 g/d
    • Pregnancy category: C; PB: 10-20%; t1⁄2: 9.5 h—Promote fluid intake
  • Rifampin (Rifadin, Rimactane): PO: 600 mg/d as a single dose
    • Pregnancy category: C; PB 85%-90%; t1⁄2: 3 h—monitor liver enzymes
  • Streptomycin SO4: IM: 1 g daily or 7-15 mg/kg/d for 2-3 mo, then
    2-3 x wk
    • Pregnancy category: C; PB: 30%; t1⁄2: 2-3 h Second-Line Drugs are:
  • Aminosalicylate sodium, P.A.S. sodium: PO: 14-16 g/d in 2-3 divided
    doses
    • Pregnancy category: C; PB: 15%; t1⁄2: 1 h—take after meals to reduce gastric irritation
  • Capreomycin (Capastat): IM: 1 g/d for 2–4 mo. Then 1 g 2-3 x per week
    • Pregnancy category: C; PB: UK; t1⁄2: 3-6 h—hearing loss is an adverse reaction; patients should take pyridoxine (to avoid peripheral neuropathy)
  • Cycloserine (Seromycin): PO: 200 mg q12 h for 2 wks; max: 1 g/d ° Pregnancy category: C; PB: UK; t1⁄2: 10 h
  • Ethionamide (Treacator-SC): PO: 250 mg, q8-12h

    • Pregnancy category: C; PB: UK; t1⁄2: 2-3h—side effects include GI discomfort. Use with caution in patients with diabetes mellitus, alcoholism, and hepatic disorder
  • Rifabutin (Mycobutin) PO: 300 mg/d in 1 or 2 divided doses
    • Pregnancy category: B; PB: 85%; t1⁄2: 16-69 h
    • Side effects and adverse reactions differ according to the drug prescribed. The nursing assessment should include:
  • History of past TB; PPD tests and reactions, chest xray and results, and previous allergy to any antitubercular drugs.
  • Medical history; most are contraindicated with severe hepatic disease (liver).
  • Assess for sign and symptoms of peripheral neuropathy.

Check for hearing changes because some of the drugs are ototoxic. Nursing diagnoses related to drug therapy for TB are:

  • Risk for infection
  • Risk for impaired tissue integrity
  • Risk for hearing loss

Nursing interventions for patients being treated for tuberculosis are:

  • Administer 1 h before or 2 h after meals.
  • Administer pyridoxine as prescribed.
  • Monitor serum liver enzymes.
  • Collect sputum specimens in early morning (usually 3 consecutive mornings).
  • Arrange for eye examinations.
  • Emphasize importance of complying with drug regimen.

Patient education:

  • Take before meals or 2 h after for better absorption.
  • Take as prescribed.
  • Do not to take antacids because they decrease TB drug absorption.
  • Keep medical appointments and have sputum tested.
  • Check with healthcare provider before becoming pregnant.
  • Report numbness, tingling, or burning of the hands and feet.
  • Avoid direct sunlight use sunblock.
  • Rifampin (urine, feces, saliva, sputum, sweat, and tears may be a harmless red-orange color; soft contact lenses may be permanently stained.
  • Evaluation: Evaluate effectiveness with sputum specimens.


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