Chapter 41
Antitubercular Drugs
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Antitubercular Drugs

Tuberculosis (TB)



Caused by Mycobacterium tuberculosis
Antitubercular drugs treat all forms of
Mycobacterium
TB is most commonly characterized by
granulomas in the lungs
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Mycobacterium Infections
Common infection sites
 Lung (primary site)
 Brain
 Bone
 Liver
 Kidney
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Mycobacterium Infections (cont’d)


Aerobic bacillus
Passed from infected:


Humans
Cows (bovine) and birds (avian)
• Much less common
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Mycobacterium Infections (cont’d)




Tubercle bacilli are conveyed by droplets
Droplets are expelled by coughing or sneezing,
and they then gain entry into the body by
inhalation
Tubercle bacilli then spread to other body organs
via blood and lymphatic systems
Tubercle bacilli may become dormant, or walled
off by calcified or fibrous tissue
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Antitubercular Drugs

First-line drugs

isoniazid (INH)*
 rifapentine
 ethambutol
 rifabutin
 pyrazinamide (PZA)
 rifampin
 streptomycin
*Primary drug used
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Antitubercular Drugs (cont’d)

Second-line drugs

capreomycin
 amikacin
 cycloserine
 levofloxacin
 ethionamide
 ofloxacin
 kanamycin
 para-aminosalicyclic acid (PAS)
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Tuberculosis-Related Injections

Purified protein derivative (PPD)


A diagnostic injection given intradermally in doses of 5
tuberculin units (0.1 mL) to detect exposure to the
tuberculosis (TB) organism
Bacille Calmette-Guérin (BCG)

A vaccine injection derived from an inactivated strain of
Mycobacterium bovis
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Antitubercular Drug Therapy
Considerations


Perform drug-susceptibility testing on the first
Mycobacterium spp. that is isolated from a patient
specimen to prevent the development of
multidrug-resistant TB (MDR-TB)
Even before the results of susceptibility tests are
known, begin a regimen with multiple
antitubercular drugs (to reduce chances of
development of resistance)
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Classroom Response Question
A patient with tuberculosis has been taking
antitubercular drugs. A sputum culture is ordered
to test for acid-fast bacilli. When is the best time
for the nurse to obtain the sputum culture?
A.
B.
C.
D.
In the morning
Noon
Five o’clock in the evening
Ten o’clock in the evening
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Antitubercular Drug Therapy
Considerations (cont’d)



Adjust drug regimen once the results of
susceptibility testing are known
Monitor patient compliance closely during therapy
Problems with successful therapy occur because
of patient nonadherence to drug therapy and the
increased incidence of drug-resistant organisms
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Mechanism of Action

Three groups



Protein wall synthesis inhibitors: streptomycin,
kanamycin, capreomycin, rifampin, rifabutin, others
Cell wall synthesis inhibitors: cycloserine, ethionamide,
INH
Other mechanisms of action: ethambutol, INH, PAS,
ethionamide
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Antitubercular Therapy

Effectiveness depends on:

Type of infection
 Adequate dosing
 Sufficient duration of treatment
 Adherence to drug regimen
 Selection of an effective drug combination
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Antitubercular Therapy (cont’d)

Problems




Drug-resistant organisms
Drug toxicity
Patient nonadherence
MDR-TB
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Isoniazid (INH)





Drug of choice for TB
Resistant strains of Mycobacterium emerging
Metabolized in the liver through acetylation—
watch for “slow acetylators”
Used alone or in combination with other drugs
Contraindicated with liver disease
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Classroom Response Question
A patient with a diagnosis of tuberculosis (TB) will be taking isoniazid
(INH) as part of the anti-TB therapy. When reviewing the patient’s chart,
the nurse finds documentation that the patient is a “slow acetylator.”
This means that:
A.
B.
C.
D.
the dosage of INH may need to be lower to prevent INH
accumulation.
the dosage of INH may need to be higher due to the slow
acetylation process.
he should not take INH.
he will need to take a combination of anti-TB drugs for successful
therapy.
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Antitubercular Therapy: Indications

Used for the prophylaxis and treatment of TB
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Adverse Effects

INH


ethambutol


Peripheral neuropathy, hepatotoxicity
Retrobulbar neuritis, blindness
rifampin

Hepatitis; discoloration of urine, stools, and other body
fluids
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Classroom Response Question
A patient is receiving isoniazid (INH) for the treatment of
tuberculosis. Which vitamin does the nurse anticipate
administering with the INH to prevent isoniazid-precipitated
peripheral neuropathies?
A. Vitamin C
B. Vitamin B12
C. Vitamin D
D. Vitamin B6
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Nursing Implications



Obtain a thorough medical history and
assessment
Perform liver function studies in patients
who are to receive INH or rifampin
(especially in elderly patients or those who use
alcohol daily)
Assess for contraindications to the various drugs,
conditions for cautious use, and potential drug
interactions
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Nursing Implications (cont’d)
Patient education is critical
 Therapy may last for up to 24 months
 Take medications exactly as ordered,
at the same time every day
 Emphasize the importance of strict adherence to
regimen for improvement of condition or cure
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Classroom Response Question
Four weeks after beginning antitubercular drug therapy on
an outpatient basis, the patient reports that he still
experiences night sweats. What does the nurse identify as
the main concern at this time?
A. He is not taking his medication properly.
B. More time is needed to see a therapeutic response.
C. His infection may be resistant to the drug therapy
ordered.
D. He may have contracted a different strain of
tuberculosis (TB).
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Nursing Implications (cont’d)
Patient education is critical (cont’d)
 Remind patients that they are contagious during
the initial period of their illness—instruct in proper
hygiene and prevention of the spread of infected
droplets
 Teach patients to take care of themselves,
including adequate nutrition and rest
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Nursing Implications (cont’d)


Patients should not consume alcohol while on
these medications or take other medications,
including over-the-counter medications, unless
they check with their prescriber
Rifampin causes oral contraceptives to become
ineffective; another form of birth control will be
needed
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Nursing Implications (cont’d)



Patients who are taking rifampin should be told
that their urine, stool, saliva, sputum, sweat, or
tears may become reddish orange; even contact
lenses may be stained
Pyridoxine may be needed to combat neurologic
adverse effects associated with INH therapy
Oral preparations may be given with meals to
reduce gastrointestinal upset, even though
recommendations are to take them 1 hour before
or 2 hours after meals
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Nursing Implications (cont’d)
Monitor for adverse effects
 Instruct patients on the adverse effects that
should be reported to the prescriber immediately
 These include fatigue, nausea, vomiting,
numbness and tingling of the extremities, fever,
loss of appetite, depression, jaundice
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Nursing Implications (cont’d)
Monitor for therapeutic effects
 Decrease in symptoms of TB, such as cough
and fever
 Lab studies (culture and sensitivity tests)
and chest x-ray should confirm clinical findings
 Watch for lack of clinical response to therapy,
indicating possible drug resistance
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Classroom Response Question
A patient has an extremely severe infection with a Mycobacterium that
is resistant to all but one antitubercular drug; however, the patient has
had an allergic reaction to that drug in the past. What does the nurse
anticipate as being ordered for this patient?
A. A combination of antitubercular drugs will be chosen to fight the
infection.
B. The patient will receive the drug and supportive care to help him
tolerate the antitubercular therapy.
C. The patient will remain on isolation precautions until his cough
clears.
D. There is nothing that can be done with this patient.
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Case Study
A home care nurse is visiting a patient with a diagnosis of TB. The
patient traveled abroad two months ago. He lives with his wife and 5year-old son. The patient tells the nurse that he is concerned his son
will also get TB so he wants to share his pills with his son. What is the
best response by the nurse?
A. “That is a good idea. Children should not be exposed to TB.”
B. “You should give your son half of the dose you take.”
C. “Do not share any of your medications with anyone. Contact your
son’s health care provider to discuss your concerns.”
D. “Children have an immune system that makes them immune to
TB.”
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Case Study (cont’d)
The patient tells the nurse, “I had a shot after I returned from my trip
overseas. I thought that was supposed to stop me from getting a
tuberculosis infection.” What information regarding tuberculosisrelated injections does the nurse identify as being true?
A. BCG is used to prevent infection with tuberculosis for women of
childbearing age.
B. A positive result for a PPD test is indicated by redness at the site
of injection.
C. PPD is a diagnostic injection given intradermally to detect
exposure to the TB organism.
D. BCG is a vaccine injection derived from an activated strain of
Mycobacterium bovis.
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Case Study (cont’d)
The patient’s wife is taking rifampin to prevent her from
developing a tuberculosis infection. Which statement by
the wife indicates that further teaching is needed?
A. “Because my oral contraceptives will not work while
I am taking rifampin, I will use another form of birth
control.”
B. “I will take the medication for one week and then
stop.”
C. “I will avoid prolonged exposure to the sun.”
D. “My urine may turn a reddish color when taking
rifampin.”
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