Anti tuberculosis Drug
Introduction:
Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis. The treatment of TB involves a combination of drugs over an extended period, typically ranging from 6 months to 2 years, depending on the disease's nature (drug-sensitive or drug-resistant). The primary goal of anti-TB therapy is to eradicate the infection, prevent transmission, and avoid the development of drug-resistant TB.
Classification of Anti-TB Drugs:
1. First-Line Drugs: These are the most effective with the least toxicity.
•Isoniazid (INH)
•Rifampicin (RIF)
•Pyrazinamide (PZA)
•Ethambutol (EMB)
•Streptomycin (SM)
2. Second-Line Drugs: Used in cases of drug-resistant TB.
•Fluoroquinolones (e.g., Levofloxacin, Moxifloxacin)
•Aminoglycosides (e.g., Amikacin, Kanamycin)
•Ethionamide
•Cycloserine
•Capreomycin
•Linezolid
•Bedaquiline
•Delamanid
•Para-aminosalicylic acid (PAS)
3. Third-Line Drugs: Less effective and more toxic, used only in extensively drug-resistant TB (XDR-TB).
•Clofazimine
•Imipenem-cilastatin
•Meropenem
Detailed Overview of Common Anti TB Drugs:
1. Isoniazid (INH)
Dose: 5 mg/kg daily (usually 300 mg once daily for adults).
Indication: Active TB (in combination), latent TB.
Contraindications: Severe hepatic dysfunction, hypersensitivity.
Adverse Effects: Hepatotoxicity, peripheral neuropathy (preventable by pyridoxine), rash.
2. Rifampicin (RIF)
Dose: 10 mg/kg daily (600 mg once daily for adults).
Indication: Active TB, latent TB, leprosy, MRSA infections.
Contraindications: Liver disease, hypersensitivity, HIV patients on protease inhibitors.
Adverse Effects: Hepatotoxicity, red-orange discoloration of body fluids, flu-like symptoms, drug interactions (induces cytochrome P450 enzymes).
3. Pyrazinamide (PZA)
Dose: 25-30 mg/kg daily (typically 1.5-2 g daily for adults).
Indication: Active TB (shortens treatment duration).
Contraindications: Severe liver disease, gout.
Adverse Effects: Hepatotoxicity, hyperuricemia (leading to gout), arthralgia.
4. Ethambutol (EMB)
Dose: 15-25 mg/kg daily (typically 800 mg-1.2 g daily for adults).
Indication: Active TB (used to prevent resistance).
Contraindications: Optic neuritis, children <5 years.
Adverse Effects: Optic neuritis (dose-related), color blindness, peripheral neuropathy.
5. Streptomycin (SM)
Dose: 15 mg/kg IM/IV daily (max 1 g daily for adults).
Indication: Drug-resistant TB, severe forms of TB (e.g., TB meningitis).
Contraindications: Pregnancy, renal impairment, hypersensitivity.
Adverse Effects: Ototoxicity (hearing loss), nephrotoxicity.
Second-Line Drugs:
1. Fluoroquinolones (Levofloxacin, Moxifloxacin)
Dose: Levofloxacin: 750-1000 mg daily; Moxifloxacin: 400 mg daily.
Indication: Multi-drug resistant TB (MDR-TB).
Contraindications: QT prolongation, hypersensitivity.
Adverse Effects: Tendonitis, QT prolongation, gastrointestinal upset.
2. Ethionamide
Dose: 500-750 mg daily.
Indication: MDR-TB.
Contraindications: Severe liver disease, psychiatric illness.
Adverse Effects: GI upset, hepatotoxicity, hypothyroidism.
3. Cycloserine
Dose: 500-750 mg daily in divided doses.
Indication: MDR-TB.
Contraindications: Epilepsy, severe depression, alcohol use.
Adverse Effects: CNS toxicity (seizures, depression), peripheral neuropathy.
4. Capreomycin
Dose: 15-20 mg/kg IM/IV daily (1 g daily for adults).
Indication: MDR-TB.
Contraindications: Renal dysfunction, hearing loss.
Adverse Effects: Nephrotoxicity, ototoxicity.
5. Bedaquiline
Dose: 400 mg daily for 2 weeks, followed by 200 mg three times per week.
Indication: MDR-TB.
Contraindications: QT prolongation, severe liver disease.
Adverse Effects: QT prolongation, hepatotoxicity, nausea.
6. Delamanid
Dose: 100 mg twice daily.
Indication: MDR-TB.
Contraindications: QT prolongation.
Adverse Effects: QT prolongation, hypokalemia, GI upset.
Indications of Anti-TB Drugs:
Active TB: Always treated with a combination of drugs (e.g., Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol for 2 months followed by Isoniazid and Rifampicin for 4 months).
Latent TB: Isoniazid or Rifampicin alone, or a combination for shorter courses.
Contraindications:
Hepatotoxicity: Avoid or closely monitor drugs like Isoniazid, Rifampicin, and Pyrazinamide in patients with liver disease.
Renal Dysfunction: Dose adjustment may be necessary for drugs like Streptomycin, Ethambutol, and Capreomycin.
Pregnancy: Some drugs (e.g., Streptomycin, Ethionamide) are contraindicated.
Adverse Effects:
Hepatotoxicity: Common with Isoniazid, Rifampicin, and Pyrazinamide.
Neurotoxicity: Peripheral neuropathy with Isoniazid and Cycloserine.
Ototoxicity and Nephrotoxicity: Common with Streptomycin and Capreomycin.
Gastrointestinal Disturbances: Common with second-line drugs like Ethionamide and Cycloserine.
Visual Changes: Ethambutol can cause optic neuritis.