Isoniazid

Description

Isoniazid is an antibiotic primarily used to treat and prevent tuberculosis (TB). It works by inhibiting the growth of Mycobacterium tuberculosis, the bacteria responsible for TB infection, thereby helping to eliminate the bacteria from the body.

Uses / Indications

• Active tuberculosis (in combination with other TB medications)
• Latent tuberculosis infection (to prevent progression to active disease)
• Certain cases of prophylaxis in high-risk populations

Dosage and Administration

Adults:
For active TB, the typical dose is 5 mg/kg (up to a maximum of 300 mg) once daily, in combination with other antituberculosis drugs. For latent TB, the usual dose is 300 mg once daily or 900 mg twice weekly.

Children:
The dose for children varies based on age and weight, typically ranging from 10 to 15 mg/kg daily. Consult a healthcare provider for precise dosing.

Note: Dosage may vary based on medical condition or doctor’s advice.

How It Works (Mechanism of Action)

Isoniazid works by inhibiting the synthesis of mycolic acids, essential components of the mycobacterial cell wall. This action interferes with the growth of the tuberculosis bacteria, effectively reducing the infection.

Side Effects

Common side effects:

• Nausea
• Fatigue
• Liver enzyme elevation
• Peripheral neuropathy (tingling or numbness in extremities)

Rare/serious side effects:

• Severe liver damage (symptoms can include jaundice, dark urine, abdominal pain)
• Allergic reactions (rash, swelling, difficulty breathing)
• Seizures

Seek medical attention if serious side effects occur.

Precautions / Warnings

• Inform your doctor if you have liver disease, diabetes, or a history of seizures.
• Use caution when consuming alcohol, as it may increase the risk of liver damage.
• Regular monitoring of liver function is recommended during treatment.

Drug Interactions

Isoniazid may interact with:

• Alcohol (increased risk of liver toxicity)
• Anticoagulants (may enhance their effects)
• Antiepileptic medications (may reduce effectiveness)
• Certain antidepressants (risk of serious side effects)

Always inform your healthcare provider about any other medications or supplements you’re taking.

Storage Instructions

• Store at room temperature (20°C–25°C / 68°F–77°F)
• Keep away from moisture, heat, and direct light
• Keep out of reach of children

Missed Dose / Overdose

Missed a dose?
Take it as soon as you remember. If it’s almost time for your next dose, skip the missed one. Do not double up.

Overdose symptoms:

• Severe nausea or vomiting
• Difficulty breathing
• Seizures
• Yellowing of the skin or eyes

Contact a poison control center or seek emergency medical help immediately.

Contraindications

• Allergic to Isoniazid or any of its components
• Previous severe reaction to Isoniazid
• Acute liver disease

Brand Names / Alternatives

• INH
• Isozid
• Rifater (in combination with rifampin and pyrazinamide)
• Generic name: Isoniazid