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Notes from the Field: National Shortage of Isoniazid 300 mg Tablets

On November 16, 2012, the Illinois State tuberculosis (TB) program notified CDC's Division of Tuberculosis Elimination of a national shortage of 300 mg tablets of the antituberculosis medication isoniazid (INH). Subsequently, other state TB programs (e.g., California, Indiana, Maryland, New York, Virginia, and Wisconsin) reported difficulty obtaining INH 300 mg tablets. Other programs (e.g., San Diego) have experienced difficulties obtaining at least one of the commercially available anti-TB preparations containing the combination of rifampin and INH (IsonaRif [VersaPharm]).

INH and rifampin are the two most important drugs used to treat TB disease and latent TB infection (LTBI). For TB disease, patients currently take up to 11 tablets a day as part of a four-drug regimen (2 rifampin 300 mg, 1 INH 300 mg, 4 pyrazinamide 500 mg, and 4 ethambutol 400 mg tablets). Fixed-dose combinations decrease tablet numbers and minimize inadvertent omission of one or more required medications, which can lead to drug-resistant TB. A shortage of 300 mg INH tablets requires an increase in the daily tablet intake for TB disease from 11 to 13 tablets and for LTBI from 1 to 3 tablets. In the United States, the LTBI treatment completion rate is about 60% for 9 months of daily INH therapy (1); increasing the number of required tablets might decrease compliance. Because of the shortage of INH 300 mg tablets, some programs (e.g., Maryland) have restricted LTBI treatment to contacts of persons with TB disease.

Currently there are three U.S. suppliers of INH: Teva, Sandoz, and VersaPharm. According to Food and Drug Administration (FDA) reports, Teva is reporting low inventory and possible backorder of INH 300 mg because of a delay in receiving its shipment of INH. Sandoz is reporting a shortage of the active ingredient from its supplier and estimates it will be able to fill orders for INH 100 mg and 300 mg in late January 2013. VersaPharm estimates it will be able to fill orders in December 2012.

CDC and FDA are collaborating to identify solutions to ensure a continuous supply of anti-TB medication. TB programs experiencing any difficulties obtaining medications are encouraged to report them to Sundari Mase,, at CDC or to their state TB program. At least one alternative of combination pills containing INH and rifampin, Rifamate (Sanofi-Aventis) is currently available. Programs should contact their pharmacy to coordinate obtaining alternative combination pills. Up-to-date information on drug availability is available at

Reported by

Neha Shah, MD, Sundari Mase, MD, Terence Chorba, MD, Kenneth Castro, MD, Div of Tuberculosis Elimination, National Center for HIV, Hepatitis, STDs, and Tuberculosis Prevention, CDC. Corresponding contributor: Neha Shah,, 510-620-3056.


  1. CDC. Targeted tuberculin testing and treatment of latent tuberculosis infection. MMWR 2000;49(No. RR-6).

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