Antituberculosis medication

Antituberculosis Medication

Antituberculosis medications are a class of drugs used to treat tuberculosis (TB), an infectious disease caused by the bacterium Mycobacterium tuberculosis. These medications are critical in the management and eradication of TB, which primarily affects the lungs but can also impact other parts of the body.

Overview

Tuberculosis is a major global health concern, and effective treatment is essential to control its spread. The standard treatment for TB involves a combination of antibiotics taken over a period of at least six months. This prolonged treatment is necessary to ensure the complete eradication of the bacteria and to prevent the development of drug-resistant strains.

First-line Antituberculosis Drugs

The first-line drugs are the most effective and least toxic medications used in the initial treatment of TB. These include:

• Isoniazid (INH): A bactericidal drug that inhibits the synthesis of mycolic acids, essential components of the mycobacterial cell wall.
• Rifampicin (RIF): A broad-spectrum antibiotic that inhibits bacterial RNA synthesis by binding to the DNA-dependent RNA polymerase.
• Ethambutol (EMB): A bacteriostatic agent that interferes with the synthesis of the mycobacterial cell wall.
• Pyrazinamide (PZA): A prodrug that is converted to its active form in acidic environments, effective against semi-dormant bacteria within macrophages.

Second-line Antituberculosis Drugs

Second-line drugs are used when resistance to first-line drugs is present or when patients cannot tolerate first-line drugs. These include:

• Fluoroquinolones: Such as levofloxacin and moxifloxacin, which inhibit bacterial DNA gyrase.
• Aminoglycosides: Such as streptomycin and amikacin, which inhibit protein synthesis by binding to the 30S ribosomal subunit.
• Capreomycin: An injectable antibiotic that inhibits protein synthesis.
• Ethionamide: A bacteriostatic agent that disrupts mycolic acid synthesis.

Drug Resistance

Drug-resistant TB is a significant challenge in TB control. Resistance can occur due to improper use of antibiotics, incomplete treatment, or transmission of resistant strains. Types of drug-resistant TB include:

• Multidrug-resistant tuberculosis (MDR-TB): Resistant to at least isoniazid and rifampicin.
• Extensively drug-resistant tuberculosis (XDR-TB): Resistant to isoniazid, rifampicin, any fluoroquinolone, and at least one of the second-line injectable drugs.

Treatment Regimens

The standard treatment regimen for drug-susceptible TB includes an initial intensive phase of two months with isoniazid, rifampicin, pyrazinamide, and ethambutol, followed by a continuation phase of four months with isoniazid and rifampicin.

For drug-resistant TB, treatment regimens are longer and more complex, often involving second-line drugs and lasting 18-24 months.

Side Effects

Antituberculosis medications can cause side effects, which vary depending on the drug. Common side effects include:

• Hepatotoxicity (liver damage) from isoniazid, rifampicin, and pyrazinamide.
• Peripheral neuropathy from isoniazid, which can be prevented with pyridoxine (vitamin B6) supplementation.
• Ocular toxicity from ethambutol, leading to vision changes.

Also see

• Tuberculosis
• Mycobacterium tuberculosis
• Drug resistance
• Infectious disease