Isoniazid
NydrazidPubChem CID 3767 · 3D model
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Blocks the tuberculosis bacterium from building a critical waxy layer in its cell wall called mycolic acid, which kills the bacteria as they try to grow and divide.
How it works
Isoniazid stops the tuberculosis bacterium from building a waxy, protective layer called mycolic acid in its cell wall. Without that layer, the bacteria die as they try to grow and divide. Because the bacteria can quickly develop resistance if isoniazid is used by itself, it's always given together with other TB medicines when treating active disease.
What it’s used for
Isoniazid is used to treat active tuberculosis, always alongside other TB drugs, and is also given on its own to prevent TB from developing in people who carry the infection but aren't yet sick, such as those with HIV or those in close contact with someone who has active TB. Its original brand, Nydrazid, is no longer sold, but the drug is still widely available generically. Its label carries a prominent warning about severe, sometimes fatal liver damage (hepatitis), a risk that rises with age and with regular alcohol use, which is why doctors monitor patients monthly and check liver blood tests periodically, especially in patients 35 and older.
- Mechanism
- Isonicotinic acid hydrazide, inhibits mycolic acid synthesis (antimycobacterial)
- Drug class
- Small molecule
- Therapeutic area
- Antibiotic