Nydrazid (Oral, Intramuscular)

Isoniazid is used to treat tuberculosis (TB) or to prevent it from coming back (reactivation). It can be given on its own or with other medicines to treat TB or to prevent its return (reactivation). This medicine may also be used for other issues as determined by your doctor.

This medicine can cause serious side effects, including liver damage. The risk of liver damage is higher in patients over 50 years of age. You and your doctor should discuss the benefits of this medicine as well as the risks of taking it.

If you are being treated for active tuberculosis (TB): To completely clear up your TB infection, you must continue taking this medicine for the entire treatment period, even if you start feeling better. This is very important. It is also crucial that you do not miss any doses.

Isoniazid is available only with your doctor's prescription.

It is very important that your doctor checks your progress at regular visits. Also, check with your doctor right away if you have blurred vision or loss of vision, with or without eye pain, during treatment. Your doctor may want you to see an ophthalmologist (eye doctor) for an eye check.

If your symptoms do not get better within 2 to 3 weeks, or if they get worse, check with your doctor.

Some foods like cheese (Swiss or Cheshire) or fish (tuna, skipjack, or Sardinella) may rarely cause reactions in some patients taking isoniazid. Check with your doctor if you experience redness or itching of the skin, a hot feeling, a fast or pounding heartbeat, sweating, chills or a clammy feeling, a headache, or lightheadedness while taking this medicine.

Liver problems may be more likely to happen if you drink alcoholic beverages regularly while taking this medicine. Also, drinking alcohol regularly may prevent this medicine from working properly. Therefore, you should strictly limit the amount of alcohol you consume while taking this medicine.

If this medicine makes you feel very tired or very weak; or causes clumsiness; unsteadiness; loss of appetite; nausea; numbness, tingling, burning, or pain in your hands and feet; or vomiting, check with your doctor immediately. These may be early warning signs of serious liver or nerve problems that could develop later.

• For diabetic patients:
• This medicine may give false test results with some urine sugar tests. Check with your doctor before changing your diet or the dose of your diabetes medicine.

In deciding to use a medicine, you and your doctor need to weigh the risks against the benefits. For this medicine, consider the following:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also inform your health care professional about any other allergies you may have, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Isoniazid can cause serious side effects in any patient. Therefore, it's especially important to discuss with the child's doctor the benefits and risks of using this medicine.

Geriatric

Patients over 50 years of age may be more likely to develop hepatitis and may be more sensitive to the effects of isoniazid than younger adults.

Breast Feeding

Studies in women suggest that this medication poses minimal risk to the infant when used during breastfeeding.

Interactions with Medicines

Some medicines should not be taken together at all, while others may be used together even if there might be an interaction. In such cases, your doctor may need to adjust the dose or take other precautions. When you are taking this medicine, it is especially important for your healthcare professional to know if you are taking any of the medicines listed below. The following interactions are based on their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be necessary in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Acetaminophen
• Amifampridine
• Bupropion
• Carbamazepine
• Domperidone
• Donepezil
• Glimepiride
• Itraconazole
• Ketoconazole
• Levodopa
• Levoketoconazole
• Methotrexate
• Pexidartinib
• Piperaquine
• Rifampin
• Tegafur

Using this medicine with any of the following medicines may increase the risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Aminosalicylic Acid
• Diazepam
• Disulfiram
• Enflurane
• Fosphenytoin
• Meperidine
• Phenytoin
• Warfarin

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used around the time of eating or with certain types of food due to potential interactions. Using alcohol or tobacco with certain medicines may also cause interactions. The following interactions are based on their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

• Ethanol

Using this medicine with any of the following may increase the risk of certain side effects but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

• food
• Tyramine Containing Food

Other Medical Problems

Other medical problems may affect the use of this medicine. Make sure to tell your doctor if you have any other medical issues, especially:

• Alcohol abuse (or history of) or
• Liver disease—There may be a higher chance of hepatitis with daily alcohol consumption or in patients with liver disease

• Kidney disease (severe)—There may be a higher chance of side effects in patients with severe kidney disease

• Seizure disorders such as epilepsy—There may be a higher chance of seizures (convulsions) in some patients

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do, they might need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

• Clumsiness or unsteadiness
• dark urine
• loss of appetite
• nausea or vomiting
• numbness, tingling, burning, or pain in hands and feet
• unusual tiredness or weakness
• yellow eyes or skin

Rare

• Blurred vision or loss of vision, with or without eye pain
• convulsions (seizures)
• fever and sore throat
• joint pain
• mental depression
• mood or other mental changes
• skin rash
• unusual bleeding or bruising

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue, are bothersome, or if you have any questions about them:

More common

• Diarrhea
• stomach pain

For injection form

• Irritation at the place of injection

Dark urine and yellowing of the eyes or skin (signs of liver problems) are more likely to occur in patients over 50 years of age.

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

In the U.S.

• Nydrazid

In Canada

• Pms-Isoniazid

Available Dosage Forms:

• Tablet
• Solution

Therapeutic Class: Antitubercular

Chemical Class: Isonicotinic Acid

Make certain your health care professional knows if you are on a low-sodium, low-sugar, or any other special diet. Most medicines contain more than just the active ingredient, and many liquid medicines contain alcohol.

If you are taking isoniazid by mouth and it upsets your stomach, take it with food. Antacids may also help. However, do not take aluminum-containing antacids within 1 hour of taking isoniazid. They may keep this medicine from working properly.

For patients taking the oral liquid form of isoniazid:

• Use a specially marked measuring spoon or other device to measure each dose accurately. The average household teaspoon may not hold the right amount of liquid.

To help clear up your tuberculosis (TB) completely, it is very important that you keep taking this medicine for the full time of treatment, even if you begin to feel better after a few weeks. You may have to take it every day for as long as 6 months to 2 years. It is important that you do not miss any doses.

Your doctor may also want you to take pyridoxine (e.g., Hexa-Betalin, vitamin B 6) every day to help prevent or lessen some of the side effects of isoniazid. This is not usually needed in children, who receive enough pyridoxine in their diet. If it is needed, it is very important to take pyridoxine every day along with this medicine. Do not miss any doses.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage forms (tablets, syrup): For preventing the return (reactivation) of tuberculosis: Adults and teenagers—300 milligrams (mg) once a day. Children—Dose is based on body weight. The usual dose is 10 mg per kilogram (kg) (4.5 mg per pound) of body weight, up to 300 mg, once a day. For treatment of tuberculosis: Adults and teenagers—300 mg once a day; or 15 mg per kg (6.8 mg per pound) of body weight, up to 900 mg, two times a week or three times a week, depending on the schedule your doctor chooses for you. Children—Dose is based on body weight. The usual dose is 10 to 20 mg per kg (4.5 to 9.1 mg per pound) of body weight, up to 300 mg, once a day; or 20 to 40 mg per kg (9.1 to 18.2 mg per pound) of body weight, up to 900 mg, two times a week or three times a week, depending on the schedule your doctor chooses for you.
• For injection dosage form: For preventing the return (reactivation) of tuberculosis: Adults and teenagers—300 mg once a day. Children—Dose is based on body weight. The usual dose is 10 mg per kg (4.5 mg per pound) of body weight, up to 300 mg, once a day. For treatment of tuberculosis: Adults and teenagers—300 mg once a day; or 15 mg per kg (6.8 mg per pound) of body weight, up to 900 mg, two times a week or three times a week, depending on the schedule your doctor chooses for you. Children—Dose is based on body weight. The usual dose is 10 to 20 mg per kg (4.5 to 9.1 mg per pound) of body weight, up to 300 mg, once a day; or 20 to 40 mg per kg (9.1 to 18.2 mg per pound) of body weight, up to 900 mg, two times a week or three times a week, depending on the schedule your doctor chooses for you.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

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