Tuesday, February 14, 2012

Home : Drugs A - Z : Isoniazid

There is an FDA Alert for this drug.
Click here to view it.

Advertisement

Isoniazid Clinical Information

a nicotinic acid derivative

Generic Name: isoniazid

Brand Names: Nydrazid

Uses

Tuberculosis

Treatment of active (clinical) tuberculosis (TB) in conjunction with other antituberculosis agents.

First-line agent for treatment of all forms of active TB caused by Mycobacterium tuberculosis known or presumed to be susceptible to the drug. Essential component of multiple-drug regimens used for the initial intensive treatment phase and the continuation treatment phase.

Fixed-combination preparation containing rifampin and isoniazid (Rifamate®) is used for treatment of pulmonary TB. Isoniazid and rifampin both are used in the initial intensive treatment phase and the continuation treatment phase, but manufacturer states that Rifamate® is not recommended for initial therapy, and the fixed-combination preparation should be used only after the patient has been treated with the individual components and efficacy of these drugs has been established.

Fixed combination preparation containing rifampin, isoniazid, and pyrazinamide (Rifater®) is used for treatment of pulmonary TB; designated an orphan drug by US FDA for this use. Used only in the initial intensive treatment phase since pyrazinamide is not usually indicated for the continuation phase.

For initial treatment of active TB caused by drug-susceptible M. tuberculosis, recommended multiple-drug regimens consist of an initial intensive phase (2 months) and a continuation phase (4 or 7 months). Although the usual duration of treatment for drug-susceptible pulmonary and extrapulmonary TB (except disseminated infections and TB meningitis) is 6–9 months, ATS, CDC, and IDSA state that completion of treatment is determined more accurately by the total number of doses and should not be based solely on the duration of therapy. A longer duration of treatment (e.g., 12–24 months) usually is necessary for infections caused by drug-resistant M. tuberculosis.

Patients with treatment failure or drug-resistant M. tuberculosis, including multidrug-resistant (MDR) TB (resistant to both isoniazid and rifampin) or extensively drug-resistant (XDR) TB (resistant to both isoniazid and rifampin and also resistant to a fluoroquinolone and at least one parenteral second-line antimycobacterial such as capreomycin, kanamycin, or amikacin), should be referred to or managed in consultation with experts in the treatment of TB as identified by local or state health departments or CDC.

Latent Tuberculosis Infection

Treatment of latent tuberculosis infection (LTBI).

LTBI is asymptomatic infection with M. tuberculosis; usually defined as a positive tuberculin skin test (TST) or Quantiferon®-TB gold test (QFT-G) with no evidence of active (clinical) TB. LTBI is treated to decrease the risk of progression to active TB.

Regimen of choice for treatment of LTBI is isoniazid monotherapy, unless the patient has been in contact with an individual with drug-resistant TB. Rifampin monotherapy is the preferred alternative and is especially useful in adults, adolescents, or children who have been exposed to isoniazid-resistant M. tuberculosis and those who cannot tolerate isoniazid. Rifabutin is used in those who cannot receive rifampin because of intolerance or because they are receiving other drugs that have clinically important interactions with rifampin (e.g., HIV patients receiving certain antiretroviral agents).

Treatment of LTBI in patients who have been exposed to a source case with drug-resistant TB, including MDR TB or XDR TB, should be managed in consultation with experts in the treatment of TB as identified by local or state health departments or CDC.

Prior to initiating treatment of LTBI, clinical (active) TB must be excluded using appropriate testing (e.g., radiographs).

Mycobacterium avium Complex (MAC) Infections

Has been used for treatment of M. avium complex (MAC) infections† in conjunction with other antimycobacterials.

Although a multiple-drug regimen of isoniazid, rifampin, and ethambutol (with streptomycin during the initial 3–6 months) has been used for treatment of MAC pulmonary infections, isoniazid is not included in current ATS, CDC, NIH, or IDSA recommendations for treatment of MAC infections, including macrolide-resistant MAC.

Treatment of MAC infections is complicated and should be directed by clinicians familiar with mycobacterial diseases; consultation with a specialist is particularly important when the patient cannot tolerate first-line drugs or when the infection has not responded to prior therapy or is caused by macrolide-resistant MAC.

Mycobacterium kansasii and Other Mycobacterial Infections

Treatment of M. kansasii infections in conjunction with other antimycobacterials. ATS and IDSA recommend a regimen of isoniazid, rifampin, and ethambutol for treatment of pulmonary or disseminated infections caused by rifampin-susceptible M. kansasii. If rifampin-resistant M. kansasii are involved, ATS and IDSA recommend a 3-drug regimen based on results of in vitro susceptibility, including clarithromycin (or azithromycin), moxifloxacin, ethambutol, sulfamethoxazole, or streptomycin.

Treatment of M. xenopi† infections in conjunction with other antimycobacterials. Optimum regimens not established; in vivo response may not correlate with in vitro susceptibility. ATS and IDSA state that a regimen of clarithromycin, rifampin, and ethambutol has been used, although the rate of relapse is high. A regimen of isoniazid, rifampin (or rifabutin), ethambutol, and clarithromycin (without or without streptomycin during initial treatment) also has been suggested.


Last Updated: February 01, 2008
Licensed from
Advertisement
Copyright © 2005 - 2012 Healthline Networks, Inc. All rights reserved.
Healthline is for informational purposes and should not be considered medical advice, diagnosis or treatment recommendations. more details