What condition is isoniazid (INH) primarily used to treat?

Isoniazid (INH) is primarily used to treat tuberculosis (TB), which is a bacterial infection caused by Mycobacterium tuberculosis. This medication is part of a combination therapy for active TB and is also used as a prophylactic treatment to prevent the infection in individuals who are at high risk of developing the disease, such as those with latent TB or people who have been in close contact with someone who has active TB.

The effectiveness of isoniazid in combating the TB bacterium is due to its ability to inhibit the synthesis of mycolic acids, which are essential components of the bacterial cell wall. This specific action is crucial for the treatment of tuberculosis, which is why isoniazid is one of the first-line agents used in TB therapy.

In contrast, pneumonia is primarily treated with antibiotics specific to the causative organism, asthma is typically managed with bronchodilators and anti-inflammatory medications, and bronchitis might be treated with bronchodilators or corticosteroids, focusing on symptom relief rather than targeting a specific bacterial infection like TB.