Trecator SC (ethionamide) is a second-line antimycobacterial agent indicated for the treatment of active pulmonary and extrapulmonary tuberculosis when first-line therapy has failed or is not tolerated. As a critical component of multidrug regimens, it works by inhibiting mycolic acid synthesis in Mycobacterium tuberculosis, disrupting cell wall integrity and leading to bactericidal effects. Its role is particularly vital in managing drug-resistant strains, offering a strategic option under specialist supervision to achieve sputum conversion and prevent disease progression.

Features

• Contains 250 mg ethionamide per scored tablet
• Oral formulation allowing for outpatient management
• Bactericidal activity against Mycobacterium tuberculosis
• Synergistic with other second-line antitubercular agents like cycloserine
• Heat-stable formulation suitable for various climates
• Scored tablets for dose adjustment when medically indicated

Benefits

• Provides a therapeutic option for multidrug-resistant (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB)
• Contributes to sputum culture conversion within treatment timelines
• Helps prevent development of further drug resistance when used in appropriate combinations
• Supports completion of therapy through oral administration
• Reduces risk of transmission through effective bacterial eradication
• Enables structured retreatment regimens under programmatic conditions

Common use

Trecator SC is primarily used as part of combination therapy for pulmonary and extrapulmonary tuberculosis that has demonstrated resistance to first-line agents (isoniazid, rifampin). It is typically incorporated into regimens following drug susceptibility testing results, often alongside agents such as fluoroquinolones, injectables, or other second-line drugs. Its use is most common in retreatment cases, MDR-TB management, and cases where first-line drugs are contraindicated due to toxicity or hypersensitivity.

Dosage and direction

Adults: 15-20 mg/kg/day orally, usually administered as 250-500 mg daily, divided into 3-4 doses with meals to minimize gastrointestinal upset. Maximum daily dose should not exceed 1,000 mg.

Pediatric patients: 15-20 mg/kg/day in 2-3 divided doses, not to exceed 750 mg daily.

Dosage must be individualized based on weight, susceptibility patterns, and regimen design. Administration with food is recommended to reduce gastric irritation. Tablets may be crushed and mixed with food for patients with swallowing difficulties. Therapy typically continues for 18-24 months depending on disease site, severity, and treatment response, always as part of a multidrug regimen designed by a tuberculosis specialist.

Precautions

• Hepatic function must be monitored monthly due to risk of hepatotoxicity
• Thyroid function should be assessed baseline and periodically as ethionamide may cause hypothyroidism
• Neurological symptoms should be monitored; pyridoxine (50-100 mg daily) is recommended to prevent neuropathy
• Use with caution in patients with diabetes mellitus due to potential for hypoglycemia
• Psychiatric history requires careful assessment as neuropsychiatric effects may occur
• Regular ophthalmological exams recommended due to possible optic neuritis risk
• Not recommended during pregnancy unless potential benefit justifies potential risk

Contraindications

• Severe hepatic impairment (Child-Pugh Class C)
• History of hypersensitivity to ethionamide or related compounds
• Uncontrolled psychiatric disorders
• Concurrent use with alcohol due to disulfiram-like reaction risk
• Acute porphyria
• Combination with certain QT-prolonging agents without careful monitoring

Possible side effects

Gastrointestinal: Nausea (30-50%), vomiting (10-20%), metallic taste, abdominal pain, diarrhea, anorexia, excessive salivation

Hepatic: Elevated transaminases (15-30%), hepatitis (2-5%), jaundice

Neurological: Peripheral neuropathy (5-15%), dizziness, headache, tremors, restlessness, depression, psychotic episodes

Endocrine: Hypothyroidism, gynecomastia, menstrual irregularities, hypoglycemia

Dermatological: Rash, photosensitivity, acneiform eruptions

Other: Orthostatic hypotension, visual disturbances, arthralgia, metallic taste

Drug interaction

• Isoniazid: Increased risk of hepatotoxicity and neurotoxicity
• Cycloserine: Enhanced CNS toxicity including seizures and psychosis
• Oral hypoglycemics/insulin: Potentiated hypoglycemic effects
• Alcohol: Disulfiram-like reaction with flushing, palpitations, hypotension
• Thyroid hormone replacements: May require dosage adjustment
• QT-prolonging agents: Possible additive effect on cardiac repolarization
• Vitamin B6: Pyridoxine supplementation recommended to prevent neuropathy

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next dose. Do not double the dose to make up for a missed one. Maintain regular dosing schedule to ensure consistent therapeutic levels. Report repeated missed doses to healthcare provider as this may compromise treatment efficacy and promote drug resistance.

Overdose

Symptoms may include severe nausea, vomiting, neurological symptoms (dizziness, confusion, seizures), and hypoglycemia. There is no specific antidote. Management involves gastric lavage if presented early, supportive care including IV fluids, antiemetics, and symptomatic treatment. Hemodialysis is not effective due to high protein binding. Monitor hepatic function, blood glucose, and neurological status closely.

Storage

Store at controlled room temperature (20-25°C or 68-77°F) in original container. Protect from light and moisture. Keep tightly closed and out of reach of children. Do not use if tablets show signs of discoloration or deterioration. Dispense in original container with child-resistant closure. Do not transfer to other containers as this may affect stability.

Disclaimer

This information is for educational purposes and does not replace professional medical advice. Trecator SC must be prescribed by a physician experienced in tuberculosis management. Treatment should be administered under direct observation therapy (DOT) programs when possible. Patient response and adverse effects require regular monitoring. Dosage adjustments should only be made by qualified healthcare professionals familiar with antituberculosis therapy.

Reviews

“Trecator SC remains an essential component of our MDR-TB regimen despite its side effect profile. With careful monitoring and supportive care, we achieve culture conversion in most cases.” - Infectious Disease Specialist, TB Reference Center

“While gastrointestinal side effects are challenging, dose titration and administration with food significantly improve tolerance. Its role in drug-resistant TB is irreplaceable.” - Clinical Pharmacist, TB Program

“After 25 years managing complex TB cases, I continue to value ethionamide’s consistent activity against resistant strains when used appropriately in combination regimens.” - Pulmonologist, TB Control Program