Isoniazid (Isoniazid 100mg) Tablets

Isoniazid general information

What is Isoniazid used for?

Isoniazid tablets 100mg are used to treat pulmonary tuberculosis, which is an infection of the lungs with the bacteria Mycobacterium tuberculosis.  Tuberculosis usually only affects the lungs but can spread to other parts of the body (extrapulmonary), including the kidneys, spine and brain.  Often there are no symptoms and this form of the disease is known as latent tuberculosis, which is kept under control by the immune system and is not contagious.  However, if the disease progresses to the active form it can become serious and even life-threatening.  Active tuberculosis is highly contagious and spreads through droplets from coughing and sneezing.  Symptoms include chronic cough, blood in the sputum, chest pain, fatigue, fever, night sweats, chills, loss of appetite and weight loss.  Risk factors for tuberculosis include immunocompromised condition like HIV/AIDS, smoking, lung disease, malnutrition, overcrowding, alcoholism, diabetes and some medications like corticosteroids.  Isoniazid tablets 100mg can be used alone for latent tuberculosis to prevent the progression to active disease, but for active tuberculosis is used in combination with other antitubercular agents such as rifampicin.  Isoniazid tablets 100mg are also effective for treatment of extrapulmonary tuberculosis.   

How does Isoniazid work?

Isoniazid tablets 100mg contain the antibiotic isoniazid that is used to treat pulmonary tuberculosis in latent form to prevent the progression to active disease, and in active form to prevent spread of infection.  Isoniazid in Isoniazid tablets 100mg has antibacterial activity only against Mycobacterium tuberculosis that causes tuberculosis.  It is a prodrug that is activated specifically by a bacterial enzyme, and this active form blocks the synthesis of an important component of the bacterial cell wall, which disrupts the cell wall and kills the bacteria.  This action of Isoniazid in Isoniazid tablets 100mg prevents spread of the infection and relieves symptoms of tuberculosis. 

What does Isoniazid contain?

Isoniazid tablets 100mg contain the active ingredient isoniazid, an antibiotic used to treat tuberculosis. They also contain lactose monohydrate magnesium stearate wheat starch purified water.

Treating tuberculosis with Isoniazid

Isoniazid tablets 100mg contain isoniazid, an antibiotic used to treat tuberculosis.  Pulmonary tuberculosis is an infection of the lungs with the bacteria Mycobacterium tuberculosis, but it can spread to other parts of the body (extrapulmonary), including the kidneys, spine and brain.  Latent tuberculosis has no symptoms but can progress to the active form, which is a serious and even life-threatening disease, with symptoms including chronic cough, blood in the sputum, chest pain, fatigue, fever, night sweats, chills, loss of appetite and weight loss.  Active tuberculosis is contagious highly and spreads through droplets from coughing and sneezing.  Isoniazid in Isoniazid tablets 100mg has antibacterial activity only against Mycobacterium tuberculosis that causes tuberculosis.  It is a prodrug that is activated specifically by a bacterial enzyme, and this active form blocks the synthesis of an important component of the bacterial cell wall, which disrupts the cell wall and kills the bacteria.  This action of Isoniazid in Isoniazid tablets 100mg prevents spread of the infection and relieves symptoms of tuberculosis. 

What are the side effects of Isoniazid?

The most commonly reported side effect when taking Isoniazid tablets 100mg is peripheral neuropathy, which is damage to the peripheral nerves causing symptoms like pain, tingling, numbness and weakness.  Other side effects include gastrointestinal upset, headache, fever, fatigue, memory impairment, seizures, hypersensitivity reactions, connective tissue disorders such as lupus erythematosus-like syndrome.  There is an increasing risk of developing hepatitis with increasing age.

When should Isoniazid not be used?

You should not use Isoniazid tablets 100mg if you:

• are allergic to isoniazid or any ingredients in Isoniazid tablets
• have a hypersensitivity reaction to Isoniazid
• are pregnant or are breastfeeding
• have kidney or liver disease
• have epilepsy or have had seizures
• have HIV infection
• have a psychotic disorder
• have diabetes mellitus
• are undernourished
• drink alcohol or have chronic alcoholism as this can cause hepatitis
• are taking medicines that interact with Isoniazid including the antiepileptics phenytoin and carbamazepine, the analgesic paracetamol, the sedative diazepam, the antifungal itraconazole, zalcitabine for HIV

What medications interact with Isoniazid?

Several medications interact with Isoniazid tablets 100mg and should either not be taken while you are taking Isoniazid or only after discussion and instruction from your doctor:

• Drugs that cause a serious reaction with Isoniazid: the analgesic paracetamol, the anti-infective rifampicin, the sedative diazepam
• Drugs that affect Isoniazid: the anti-infective rifampicin, zalcitabine for HIV
• Drugs that are affected by Isoniazid: the antiepileptics phenytoin and carbamazepine, the analgesic paracetamol, the anti-infective rifampicin, the antifungal itraconazole

How should Isoniazid be taken?

You should take your Isoniazid tablets 100mg swallowed whole with a glass of water.  The dose you take should be as recommended by your doctor and based on your body weight (4-5mg/kg or 1.8-2.2mg/lb body-weight), up to a maximum of 300 mg daily.  You can take your Isoniazid tablets 100mg as a single dose or divided into multiple doses through the day, depending on your doctor’s recommendation.  You should continue to take your Isoniazid tablets 100mg for as long as recommended by your doctor, which is usually for several months, depending on whether you are being treated for active or latent tuberculosis and whether you are taking a combination of medications. 

How long should you take Isoniazid?

You should continue to take your Isoniazid tablets 100mg for as long as recommended by your doctor, which is usually for several months, depending on whether you are being treated for active or latent tuberculosis and whether you are taking a combination of medications. 

Missed dose of Isoniazid

If you miss a dose of Isoniazid tablets 100mg take it as soon as you remember, unless it is time to take the next dose, then skip the missed dose.  Do not take a double dose.

How should Isoniazid be stored?

You should store your Isoniazid tablets 100mg below 25°C in a cool dry place.