chapter 41 antitubercular drugs copyright © 2014 by mosby, an imprint of elsevier inc

Chapter 41

Antitubercular Drugs

Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Tuberculosis (TB) Caused by Mycobacterium tuberculosis

Antitubercular drugs treat all forms of Mycobacterium

TB is most commonly characterized by granulomas in the lungs


Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 2

Common infection sites Lung (primary site) Brain Bone Liver Kidney

Mycobacterium Infections


Aerobic bacillus Passed from infected:

Humans Cows (bovine) and birds (avian)

• Much less common

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

Mycobacterium Infections (cont’d)


First-line drugs isoniazid (INH)* rifapentine ethambutol rifabutin pyrazinamide (PZA) rifampin streptomycin

*Primary drug used



Second-line drugs capreomycin amikacin cycloserine levofloxacin ethionamide ofloxacin kanamycin para-aminosalicyclic acid (PAS)

Antitubercular Drugs (cont’d)


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

Tuberculosis-Related Injections


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)

Antitubercular Drug TherapyConsiderations


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.In the morning

B.Noon

C.Five o’clock in the evening

D.Ten o’clock in the evening


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

Antitubercular Drug TherapyConsiderations (cont’d)


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

Mechanism of Action


Effectiveness depends on: Type of infection Adequate dosing Sufficient duration of treatment Adherence to drug regimen Selection of an effective drug combination

Antitubercular Therapy


Problems Drug-resistant organisms Drug toxicity Patient nonadherence

MDR-TB

Antitubercular Therapy (cont’d)


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

Isoniazid (INH)



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.the dosage of INH may need to be lower to prevent INH accumulation.

B.the dosage of INH may need to be higher due to the slow acetylation process.

C.he should not take INH.

D.he will need to take a combination of anti-TB drugs for successful therapy.


Used for the prophylaxis and treatment of TB

Antitubercular Therapy: Indications


INH Peripheral neuropathy, hepatotoxicity

ethambutol Retrobulbar neuritis, blindness

rifampin Hepatitis; discoloration of urine, stools, and other body

fluids

Adverse Effects



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


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

Nursing Implications


Patient education is criticalTherapy may last for up to 24 monthsTake medications exactly as ordered, at the same time every dayEmphasize the importance of strict adherence to regimen for improvement of condition or cure

Nursing Implications (cont’d)



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).


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 dropletsTeach patients to take care of themselves, including adequate nutrition and rest



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



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



Monitor for adverse effectsInstruct patients on the adverse effects that should be reported to the prescriber immediatelyThese include fatigue, nausea, vomiting, numbness and tingling of the extremities, fever, loss of appetite, depression, jaundice



Monitor for therapeutic effectsDecrease in symptoms of TB, such as cough and feverLab studies (culture and sensitivity tests) and chest x-ray should confirm clinical findingsWatch for lack of clinical response to therapy, indicating possible drug resistance




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.


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 5-year-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.”


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 tuberculosis- related 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.


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.”


chapter 41 antitubercular drugs copyright © 2014 by mosby, an imprint of elsevier inc

Documents

imprint of elsevier

evening copyright

multiple antitubercular

primary drug

drug regimen

forms of mycobacterium

drugsusceptibility testing

line drugs isoniazid