WHAT IS ISONIAZID USED FOR?

Isoniazid (Isonicotinic Acid Hydrazide): Uses, Side Effects, and More

Isoniazid is primarily used to treat active tuberculosis infections caused by Mycobacterium tuberculosis. It is also prescribed for latent TB infection (LTBI) to prevent the development of active TB disease. Additionally, it can be part of a combination therapy regimen to manage multidrug-resistant TB.

How Does Isoniazid Work?

Isoniazid works by inhibiting mycolic acid synthesis in Mycobacterium tuberculosis. This disruption interferes with the bacterium's cell wall formation, leading to bacterial death. By targeting a specific enzyme called catalase-peroxidase (KatG), Isoniazid creates toxic compounds that damage the TB bacteria.

Isoniazid Side Effects Explained

While effective in treating and preventing TB, Isoniazid can cause several side effects:

• Nervous System Issues: Peripheral neuropathy (tingling or numbness), headache, dizziness.
• Gastrointestinal Problems: Nausea, vomiting, loss of appetite, abdominal pain.
• Hepatotoxicity: Liver damage can occur, especially in individuals with pre-existing liver conditions.
• Allergic Reactions: Rash, itching, swelling (especially around the face and throat).

Isoniazid Dosage Guide

The dosage of Isoniazid depends on various factors such as age, weight, and severity of TB infection. Common dosages include:

• Adults: 300 mg daily or 5 mg/kg body weight per day.
• Pediatric Patients: 10-20 mg/kg/day divided into two doses.

It is crucial to follow the prescribed regimen strictly and complete the full course of treatment, even if symptoms improve before the end of therapy.

Isoniazid vs Other TB Drugs

Isoniazid is often used in combination with other anti-TB drugs such as Rifampin, Ethambutol, and Pyrazinamide. These combinations enhance efficacy and reduce the risk of developing drug-resistant strains:

• Rifampin: Effective against TB bacteria but can cause liver toxicity.
• Ethambutol: Prevents bacterial growth without causing resistance.
• Pyrazinamide: Highly effective during the initial phase of treatment.

Can You Drink Alcohol on Isoniazid?

Drinking alcohol while taking Isoniazid is generally not recommended. Alcohol can increase the risk of liver damage, which is already a concern with this medication. It's best to avoid or limit alcohol consumption during treatment.

Isoniazid During Pregnancy & Breastfeeding

Pregnant women should use Isoniazid cautiously under medical supervision due to potential risks:

• Pregnancy: The benefits of treating TB outweigh the risks, but close monitoring is essential.
• Breastfeeding: Small amounts may pass into breast milk; consult a healthcare provider for guidance.

How Long Does Isoniazid Stay in Your System?

Isoniazid has a half-life of approximately 1-3 hours, but its effects can last longer. The drug is metabolized by the liver and excreted through urine. Complete elimination from the body may take several days.

Isoniazid for Latent Tuberculosis

For latent TB infection (LTBI), Isoniazid is often prescribed as a preventive treatment:

• Dosing: 300 mg daily or 600 mg weekly.
• Treatment Duration: Typically 9 months for daily dosing and 12 weeks for weekly dosing.

Isoniazid Interactions with Medications

Isoniazid can interact with several medications, including:

• Rifampin: Increases metabolism of Isoniazid, reducing its effectiveness.
• Lithium: May increase lithium levels in the blood.
• Warfarin: Can enhance anticoagulant effects.

Stopping Isoniazid Suddenly: Risks

Sudden discontinuation of Isoniazid can lead to relapse or worsening of TB symptoms. It is important to taper off the medication under medical supervision and only stop it as directed by a healthcare provider.

Conclusion

Isoniazid remains an essential tool in the fight against tuberculosis, offering effective treatment for both active and latent infections. However, its use requires careful management due to potential side effects and interactions with other medications. Always consult your healthcare provider before starting or adjusting Isoniazid therapy.