Tuberculosis is caused by Mycobacterium tuberculosis and was once incurable but now treatable with anti-tubercular drugs. These drugs are classified as primary/standard or secondary/reserve drugs and include isoniazid, rifampicin, streptomycin, pyrazinamide, ethambutol, para-aminosalicylic acid, thiacetazone, capreomycin, kanamycin, ethionamide, and cycloserine. The primary drugs are bactericidal while the secondary drugs treat multi-drug resistant strains. A standard short-term regimen involves taking isoniazid, rifampicin, ethambutol, and pyrazinamide daily for 2 months

1. ANTI-TUBERCULAR
DRUGS
Yogapriya.v
B.Opt(IIIyr)

2. INTRODUCTION
• Tuberculosis is an infectious disease caused by the mycobacteria M.tuberculosis
• It was once considered to be an incurable disease
• But now,effective chemotherapeutic agents are available for its treatment

3. CLASSIFICATION OF DRUGS
PRIMARY OR STANDARD DRUGS SECONDARY OR RESERVE DRUGS
i) BACTERICIDAL
• Isonicotinic acid hydrazide
• Rifampicin
• Streptomycin
• pyrazinamide
i) BACTERICIDAL
• Capreomycin
• kanamycin
ii) BACTERIOSTATIC
• Ethambutol
• Para aminosalicylic acid
• thiacetazone
ii) BACTERIOSTATIC
• Ethionamide
• cycloserine

4. PRIMARY OR STANDARD DRUGS
(bactericidal)

5. ISONICOTINIC ACID HYDRAZIDE (INH)
• It is the mosteffective drug used in the treatment of tuberculosis
• It is a tuberculocidal drug
Mechanism of action
• INH acts by inhibiting the synthesis of mycolic acid
• It is an unique fatty acid component of mycobacterial cellwall
Absorption,fate and excretion
• INH is well absorbed on both oral and parenteral administration
• It is distributed in all body tissues and fluids including CSF
• It is mainly metabolized in liver by acetylation
• It is almost completely excreted in urine within 24 hours

6. Adverse reaction
• Intolerence like fever,malaise or jaundice
• Peripheral neuritis due to pyridoxine deficiency is an important toxicity
• CNS effects like convulsion and psychosis
• Epigastric distress,dryness of mouth and urinary retention
Preparation and dose
Isoniazid tablet-300mg daily by oral route

7. RIFAMPICIN
• It is a semisynthetic derivative of rifamycin B(isolated from Streptomyces mediteranei)
• It is bactericidal and it acts by inhibiting DNA dependent RNA polymerase
• It is well absorbed on oral administration
• It is widely distributed in tissues
• It is metabolized to desacetyl rifampicin
• This metabolite is equally tuberculocidal and undergoes enterohepatic circulation
Adverse reaction
• Hepatitis is the major adverse effect
• Also it produces skin rashes,eosinophilia and leucopenia
• Rifampicin imparts an orange red color to urine,sweat,tear and other secretion
Dose
450 mg daily by mouth

8. PRIMARY OR STANDARD DRUGS
(bacteriostatic)

9. ETHAMBUTOL
• It is a bacteriostatic drug
• It is used with other bactericidal drug as a substitute for PAS
• It is effective against mycobacteria resistant to INH,PAS and streptomycin
• It is absorbed after oral administration
Adverse reaction
Optic neuritis and peripheral neuritis
Dose
800 mg per day by oral route

10. PARA AMINOSALICYLIC ACID(PAS)
• It is a synthetic compound which is less potent than streptomycin or INH
Dose
• Dose is high =10-15 g daily
• So it is rarely used now
THIACETAZONE
• It is a thiosmicarbazone derivative
• It is used with INH or as a substitute for PAS
• It is absorbed orally
• It crosess placenta and also secreted in milk
Adverse reaction
Drug fever,skin rashes,anemia,liver and kidney damage

11. SECONDARY OR RESERVE DRUGS

12. CAPREOMYCIN
• It is a polypeptide antibiotic obtained from Streptomyces capreolus
• it is inactivated in the gastrointestinal tract
• So it is administered by parenteral route
• It is effective against mycobacteria resistant to drug of first choice
Adverse effects
Allergy,renal disturbances and 8th nerve damage
KANAMYCIN
• It is an aminoglycoside antibiotic obtained from Streptomyces kanamyceticus
• it is effective against mycobacteria resistant todrug of first choice
• It is completely absorbed from the gut
Adverse effect
Nephrotoxicity and 8th nerve damage

13. ETHIONAMIDE
• It is chemically related to INH
• It is effective against tubercle bacilli resistant to other drugs
• It act by inhibiting protein synthesis
• It is rapidly absorbed from gastrointestinal tract
• A significant concentration is present in CSF
Adverse reaction
Allergic reactions,gastrointestinal symptoms and neurological disturbances
CYCLOSERINE
• It is an antibiotic having tuberculostatis effect
• It is well absorbed from the gut
• Significant concentration is present in CSF
Adverse effects
• Neurologic and psychic effets

14. NEWER DRUGS
• Fluoroquinalones like ciprofloxacin and ofloxacin
• Macrolids like clarithromycin and azithromycin
• Rifabutin which is related to rifampicin
• They are used in multi-drug resistant tuberculosis in combination with other drugs

15. Followed by (for 4 months)
SHORT TREM REGIMEN FOR TUBERCULOSIS ( for 2 months)
INH 300 mg
RIFAMPICIN 450 mg
ETHAMBUTOL 800 mg
PYRAZINAMIDE 1.5 g
INH 300 mg
RIFAMPICIN 450 mg

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