Primary and Secondary Line of Chemotherapy in Tuberculosis

(a) Primary Line of Chemotherapy

The primary line of chemotherapy for tuberculosis (TB) consists of a standard regimen known as the “RIPE” therapy, which includes:

1. Rifampicin (RIF): An antibiotic that inhibits bacterial RNA synthesis.
2. Isoniazid (INH): A drug that interferes with the synthesis of mycolic acids in the bacterial cell wall.
3. Pyrazinamide (PZA): A prodrug that is converted to pyrazinoic acid, which disrupts mycobacterial membrane metabolism and transport functions.
4. Ethambutol (EMB): An agent that inhibits the synthesis of arabinogalactan, an essential component of the mycobacterial cell wall.

This combination is typically administered for a duration of 6 months for drug-susceptible TB.

(b) Secondary Line of Chemotherapy

Secondary line treatments are used when there is resistance to first-line drugs or when patients experience severe side effects. These include:

1. Fluoroquinolones: Such as levofloxacin or moxifloxacin, which inhibit bacterial DNA gyrase.
2. Injectable agents: Such as amikacin, kanamycin, or capreomycin, which are used in more severe cases.
3. Linezolid: An oxazolidinone antibiotic effective against resistant strains.
4. Bedaquiline and Delamanid: Newer agents specifically developed for multidrug-resistant TB.

Possible Side Effects of Anti-TB Drugs

• Rifampicin: Hepatotoxicity, orange discoloration of bodily fluids, flu-like symptoms.
• Isoniazid: Hepatotoxicity, peripheral neuropathy (prevented by pyridoxine), seizures.
• Pyrazinamide: Hepatotoxicity, hyperuricemia leading to gout.
• Ethambutol: Optic neuritis leading to vision changes.

Short Term Chemotherapy of Tuberculosis According to Classification

Short-term chemotherapy is classified based on the type and severity of TB:

1. Pulmonary TB (Drug-Susceptible):
   • Standard treatment involves a 6-month regimen with RIPE therapy as mentioned above.
2. Extrapulmonary TB:
   • Treatment duration may vary; however, a similar 6-month regimen is often employed depending on the site affected.
3. Severe Forms (e.g., Miliary TB):
   • May require prolonged treatment beyond 6 months and close monitoring due to potential complications.

DOTS Strategy in Tuberculosis

The Directly Observed Treatment Short-course (DOTS) strategy is a globally recognized approach to TB management developed by the World Health Organization (WHO). It includes five key components:

1. Political Commitment: Ensuring government support for TB control programs.
2. Case Detection through Sputum Microscopy: Early identification of infectious cases using reliable diagnostic methods.
3. Standardized Treatment Regimen with Supervised Intake: Administering a standardized short-course treatment under direct observation to ensure adherence and completion.
4. Regular Drug Supply: Ensuring uninterrupted availability of quality anti-TB drugs.
5. Monitoring and Evaluation System: Tracking treatment outcomes and program performance through systematic data collection.

Role of Corticosteroids in the Treatment of Tuberculosis

Corticosteroids play a supportive role in specific forms of tuberculosis where inflammation contributes significantly to morbidity:

1. Tuberculous Meningitis: Corticosteroids can reduce inflammatory complications and improve outcomes when given alongside anti-TB therapy.
2. Pleural Effusion or Pericarditis due to TB: They help manage inflammation and fluid accumulation but should be used cautiously alongside anti-TB medications.

Corticosteroids are not routinely recommended for uncomplicated pulmonary tuberculosis due to potential adverse effects on immune response.

Treatment Outline for Multi-Drug Resistant (MDR) Tuberculosis

MDR-TB is defined as resistance to at least rifampicin and isoniazid, necessitating specialized treatment regimens:

1. Extended Duration Therapy: Typically lasts 18-24 months or longer based on susceptibility testing results.
2. Second-Line Drugs Combination Therapy:
   • Use fluoroquinolones combined with injectable agents like amikacin or kanamycin along with other second-line oral agents such as linezolid or clofazimine depending on resistance patterns.
3. Individualized Treatment Plans: Based on drug susceptibility testing results; careful monitoring for side effects is crucial due to increased toxicity risk associated with second-line drugs.

In some cases, newer agents like bedaquiline or delamanid may be included in treatment regimens tailored specifically for MDR-TB patients.