Respiratory System Drugs
Antitubercular Drugs
Antitubercular Drugs
• Tuberculosis (TB)
• Caused by Mycobacterium tuberculosis
• Antitubercular drugs treat all forms of
Mycobacterium
Antitubercular Drugs
Mycobacterium Infections
Common infection sites
•
•
•
•
•
Lung (primary site)
Brain
Bone
Liver
Kidney
• Aerobic bacillus
• Passed from infected:
– Humans
– Cows (bovine) and birds (avian)
• Much less common
Antitubercular Drugs
Mycobacterium Infections
• Tubercle bacilli are conveyed by droplets
• Droplets are expelled by coughing or sneezing, 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
Antitubercular Drugs
Tuberculosis - Pathophysiology
• M. tuberculosis – gram-positive, acid-fast bacillus
• Spread from person to person via airborne
droplets
– Coughing, sneezing, speaking – disperse organism and
can be inhaled
– Not highly infectious – requires close, frequent, and
prolonged exposure
– Cannot be spread by hands, books, glasses, dishes, or
other fomites
Antitubercular Drugs
Tuberculosis – Clinical Manifestations
• Early stages – free of symptoms
– Many cases are found incidentally
• Systemic manifestations:
– Fatigue, malaise, anorexia, weight loss, low-grade fevers, night sweats
– Weight loss – occurs late
– Characteristic cough – frequent & produces mucoid or mucopurulent
sputum
– Dull or tight chest pain
• Some cases: acute high fever, chills, general flulike symptoms,
pleuritic pain, productive cough
• HIV Pt with TB: Fever, cough, weight loss –
– Pneumocystic carinii pneumonia (PCP)
Antitubercular Drugs
Tuberculosis – Diagnostic Studies
• Tuberculin Skin Testing -- + reaction 2-12 weeks after the initial
infection
– PPD – Purified protein derivative – used to detect delayed
hypersensitivity response
• Two-step testing – health care workers
• 5mm > induration – Immunosuppressed patients
• 10 mm> “at risk” populations & health are workers
• 15 mm> Low risk people
– Chest X-ray -- used in conjunction with skin testing
• Multinodular lymph node involvement with cavitation in the upper
lobes of the lungs
• Calcification – within several years after infection
– Bacteriologic Studies –
• Sputum, gastric washings –early morning specimens for acid-fast
bacillus -- three consecutive cultures on different days
• CSF or pus from an abscess
Antitubercular Drugs
Tuberculosis – Medical Management
• May be treated as outpatient
– Depends on debility and severity of symptoms
• Mainstay of treatment: drug therapy for active disease:
– Five primary drugs:
• Isoniazid (INH) * (primary drug used)
• Rifampin
• Pyrazinamide
• Streptomycin
• Ethambutol
– Combination 4 drug therapy
– HIV patients cannot take rifampin – interferes with antiretroviral drug
effectiveness
Antitubercular Drugs
Second-Line Drugs
capreomycin
cycloserine
ethionamide
kanamycin
para-aminosalicyclic
amikacin
levofloxacin
ofloxacin
acid (PAS)
Antitubercular Drug Therapy
Considerations
• Perform drug-susceptibility testing on the first
Mycobacterium sp. that is isolated from a patient specimen to
prevent the development of MDR-TB(Multidrug-resistant TB)
• Even before the results of susceptibility tests are known,
begin a regimen with multiple antitubercular drugs
• Adjust drug regimen once the results of susceptibility testing
are known
• Monitor patient compliance closely during therapy
• Problems with successful therapy
– patient nonadherence to drug therapy
– increased incidence of drug-resistant
Antitubercular Therapy
Effectiveness depends upon:
•
•
•
•
•
Type of infection
Adequate dosing
Sufficient duration of treatment
Drug compliance
Selection of an effective drug combination
Antitubercular Therapy
Problems
• Drug-resistant organisms
• Drug toxicity
• Patient noncompliance
• Multidrug-resistant TB (MDR-TB)
Antitubercular Drugs
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
• Used for the prophylaxis or treatment of TB
Antitubercular Drugs
Adverse Effects
• INH
– Peripheral neuritis, hepatotoxicity
• Ethambutol
– Retrobulbar neuritis, blindness
• Rifampin
– Hepatitis, discoloration of urine, stools
Antitubercular Drugs
Nursing Implications
• Thorough medical history and physical assessment
• Perform liver function studies in patients who are to
receive isoniazid 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
Antitubercular Drugs
Nursing Implications
Monitor for therapeutic effects
• Decrease in symptoms of TB, such as cough and
fever
• C&S and CXR should confirm clinical findings
• Observe for lack of clinical response to therapy,
indicating possible drug resistance
Monitor for adverse effects
• Instruct patients on the adverse effects that should
be reported to the physician immediately
– fatigue, nausea, vomiting, numbness and tingling of the
extremities, fever, loss of appetite, depression, jaundice
Antitubercular Drugs
Patient Education
Patient education is critical
• Therapy may last for up to 24 months
• Take medications exactly as ordered, the same time every day
• Emphasize the importance of strict adherence to regimen for
improvement of condition or cure
• 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
• Emphasize to patients to take care of themselves, including adequate
nutrition and rest
Antitubercular Drugs
Patient Education
• Patients should not consume alcohol or take other medications,
including OTC -- check with their physician
• INH and rifampin cause 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 (Vitamin B6) may be needed to combat neurologic
adverse effects associated with INH therapy
• 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