First-Line Treatment of TB for Drug-Sensitive TB
Shown here are the four drugs in the standard regimen of first-line drugs. Also shown are the dates these four drugs were discovered—all more than 40 years ago.
Tuberculosis, which results from an infection with Mycobacterium tuberculosis, can be cured with a combination of first-line drugs taken daily for several months.
Multidrug-Resistant Tuberculosis (MDR TB) and Second-Line Treatments
MDR TB occurs when a Mycobacterium tuberculosis strain is resistant to isoniazid and rifampin, two of the most powerful first-line drugs. To cure MDR TB, healthcare providers must turn to a combination of second-line drugs, several of which are shown here. Second-line drugs may have more side effects, the treatment may last much longer, and the cost may be up to 100 times more than first-line therapy. MDR TB strains can also grow resistant to second-line drugs, further complicating treatment.
Extensively Drug-Resistant Tuberculosis (XDR TB) - Options for Treatment
Bedaquiline and Delamanid are new drugs. Ethambutol, Pyrazinamide, Thioamides, Cycloserine, Para-aminosalicylic acid, Streptomycin, and Clofazimine are possibly effective. Kanamycin, Capreomycin and Amikacin are injectable second-line.
XDR TB occurs when a Mycobacterium tuberculosis strain is resistant to isoniazid and rifampin, two of the most powerful first-line drugs, as well as key drugs of the second line regimen—any fluoroquinolone and at least one of the three injectable drugs shown above. XDR TB strains may also be resistant to additional drugs, greatly complicating therapy.
New Candidate TB Drugs Under Development
Several new types of TB drugs currently under development are shown here. NIAID has supported the development of five of these compounds, SQ-109, PA-824 (Pretomanid), Sutezolid, Linezolid, and Meropenem, which are denoted by asterisks (*) above.
Mechanisms of Action of Current TB Drugs
Thioamides, Nitroimidazoles, Ethambutol, and Cycloserine act on cell wall synthesis. Diarylquinoline inhibits ATP synthase. PAS, Fluoroquinolones, Cyclic Peptides and Aminoglycosides act on the DNA.
Tuberculosis drugs target various aspects of Mycobacterium tuberculosis biology, including inhibition of cell wall synthesis, protein synthesis, or nucleic acid synthesis. For some drugs, the mechanisms of action have not been fully identified.
Mechanisms of Action of TB Drugs Under Development
Nitroimidazoles, SQ-109,, Meropenem, and Benzothiazinones act on cell wall synthesis. Imidazopyridine Amide inhibits ATP synthesis. Rifamycins, Oxazolidinones and Macrolides act on DNA.
Tuberculosis drugs target various aspects of Mycobacterium tuberculosis biology, including inhibition of cell wall synthesis, protein synthesis, or nucleic acid synthesis. For some drugs, the mechanisms of action have not been fully identified.
About the Illustrations
The photo of Mycobacterium tuberculosis is from the Centers for Disease Control and Prevention, CDC/Dr. Ray Butler, Janice Carr. This illustration is in the public domain. Please credit the National Institute of Allergy and Infectious Diseases (NIAID).
Additional TB Information
- Working Group on New TB Drugs
- Handbook of Anti-Tuberculosis Agents (PDF) 2008
- TB Alliance