Respiratory System Drugs

Antitubercular Drugs

Antitubercular Drugs

• Tuberculosis (TB)• Caused by Mycobacterium tuberculosis• Antitubercular drugs treat all forms of

Mycobacterium

Antitubercular DrugsMycobacterium 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 DrugsMycobacterium 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 DrugsTuberculosis - 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 DrugsTuberculosis – 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 DrugsTuberculosis – 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 DrugsTuberculosis – 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 Drugscapreomycin amikacincycloserine levofloxacinethionamide ofloxacin kanamycinpara-aminosalicyclic acid (PAS)

Antitubercular Drug TherapyConsiderations

• 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 DrugsNursing 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 DrugsNursing 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 DrugsPatient 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 DrugsPatient 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