Antitubercular

Antitubercular Drugs
Chapter 40

I Tuberculosis
A. Caused by Mycobacterium tuberculosis
1. aerobic bacillus
2. passed from infected:
a. humans
b. cows (bovine)
c. birds (avian)
B. Common infection sites
1. lung (primary)
2. brain
3. bone
4. liver
5. kidney
C. infections
1. tubercle bacilli are conveyed by droplets
2. droplets are expelled by coughing or sneezing, then gain entry into the body by inhalation.
3. tubercle bacilli then spread to other body organs via blood and lymphatic systems
4. tubercle bacilli may become dormant, or walled off by calcified or fibrous tissue
II Antitubercular Agents *used in combination
A. First line
1. isoniazid (most frequently used)
2. ethambutol
3. pyrazinamide (PZA)
4. rafampin
5. streptomycin
B. second line agents (b/c of resistance)
1. capreomycin
2. cycloserine
3. ethionamide
4. kanamycin
5. para-aminosalicyclic acid (PAS)
III Mechanism of action (3 groups)
A. Protein wall synthesis inhibitors
1. streptomycin
2. kanamycin
3. capreomycin
4. rifampin
5. rifabutin


B. Cell wall synthesis inhibitors
1. cycloserine
2. ethionamide
3. isoniazid
a. drug of choice for TB
b. restistant strains of Mycobacterium emerging
c. metabolized in the liver through acetylation – watch for “slow acetylators”
d. used alone or in combination with other agents
e. indications
i. used for the prophylaxis or treatment of TB (for 6 months)
C. Other mechanisms of action
IV Antitubucular therapy
A. Effectiveness depends on:
1. type of infection
2. adequate dosing
3. sufficient duration of treatment
4. drug compliance
5. selection of an effective drug combination
6. resistance and compliance are a big problem
B. Problems
1. drug-resistant organisms
a. multidrug-resistant TB (MDR-TB)
2. drug toxicity
3. patient noncompliance
V Side Effects
A. INH (Isoniazid)
1. peripheral neuritis (inflammation of nerve endings)
2. hepatotoxicity
B. Ethambutol
1. retrobulbar neuritis
2. blindness
C. Rifampin
1. hepatitis
2. discoloration of urine (red/orange) and stools
VI Nursing Implications
A. Obtain a thorough medical history and assessment
B. perform liver function studies in pts who are to receive isoniazid or rifampin (esp in elderly pts or those who use alcohol daily)
C. Discontinue meds when liver enzymes rise to 4x higher than baseline.
SGOT = liver test. Watch tylenol consumption (or anything liver altering)
D. Assess for contraindications to the various agents, conditions for cautious use, and potential drug interactions


E. Patient education is critical
1. therapy may last up to 24 months
2. take meds exactly as ordered, at the same time everyday
3. emphasize the importance of strict compliance to regimen for improvement of condition or cure
4. remind pts that they are contagious during the initial period of their illness. Instruct in proper hygiene and prevention of the spread of infected droplets
5. emphasize to pts to take care of themselves, including adequate nutrition and rest
F. pts should not consume alcohol while on these meds or take other meds including OTC, unless they check with their physician
G. diabetic pts taking INH should monitor blood glucose levels b/c hyperglycemia may occur
H. INH and rifampin cause oral contraceptives to become ineffective; another form of birth control will be needed
I. Pts who are taking rifampin should be told that their urine, stool, salive, sputum, sweat, or tears may become reddish/orange; even contact lenses may be stained.
J. pyridoxine MUST be given with INH therapy to combat neuroligic side effects
K. Oral preparations may be given with meals to reduce GI upset, even though recommendations are to take them 1 hour before or 2 hours after meals.
L. Monitor for side effects
1. instruct pts on the side effects that should be reported to the physician immediately
2. these include fatigue, nausea, vomiting, numbness and tingling of the extremities, fever, loss of appetite, depression, jaundice
M. Monitor for therapeutic effects
1. decrease in symptoms of TB, such as cough and fever
2. lab studies (c&S tests) and CXR should confirm clinical findings
3. watch for lack of clinical response to therapy, indicating possible drug resistance



Antitubercular agents treat all forms of Mycobacterium