What is Zidovudine?

Zidovudine has been associated with hematologic toxicity, including neutropenia and severe anemia, particularly in patients with advanced HIV disease. Prolonged use of zidovudine has been associated with symptomatic myopathy. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported. Suspend treatment if clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity occur .

Zidovudine (also known as AZT) is used together with other medicines for the treatment of human immunodeficiency virus (HIV) infection. HIV is the virus that causes acquired immune deficiency syndrome (AIDS). Zidovudine is used to slow the progression of disease in patients infected with HIV who have advanced symptoms, early symptoms, or no symptoms at all. This medicine is also used to help prevent pregnant women who have HIV from passing the virus to their babies during pregnancy and at birth.

Zidovudine will not cure or prevent HIV infection or AIDS, however, it helps keep HIV from reproducing and appears to slow down the destruction of the immune system. This may help delay the development of problems that usually result from AIDS or HIV disease. Zidovudine will not keep you from spreading HIV to other people. People who receive this medicine may continue to have the problems usually related to AIDS or HIV disease.

This medicine is available only with your doctor's prescription.

Take this medicine exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. Also, do not stop taking this medicine without checking with your doctor first. When your supply of this medicine is running low, contact your doctor or pharmacist ahead of time. Do not allow yourself to run out of this medicine.

This medicine comes with a patient information sheet. Read and follow the instructions carefully. Ask your doctor if you have any questions.

Keep using zidovudine for the full time of treatment, even if you begin to feel better. It is also important to take this medicine together with other medicines for HIV. Be sure to take all of the medicines your doctor ordered, and to take them at the right times. Only take medicine that your doctor has prescribed specifically for you. Do not share your medicine with other people.

For patients using zidovudine oral solution or syrup:

• Shake it before use. 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.

This medicine works best when there is a constant amount in the blood. To help keep the amount constant, do not miss any doses. If you need help in planning the best times to take your medicine, talk with your doctor.

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 HIV infection:
  • For oral dosage forms (capsules, solution, syrup, and tablets):
    • Adults—300 milligrams (mg) 2 times a day in combination with other anti-HIV medicines.
    • Children and infants 4 weeks of age and older—Dose is based on body weight or body size and must be determined by your child's doctor.
      • Weighs 30 kilograms (kg) or more—600 milligrams (mg) per day or 480 milligrams per square meter of body surface area (mg/m²) a day in divided doses.
      • Weighs 9 kg to less than 30 kg—18 mg per kg per day in divided doses.
      • Weighs 4 kg to less than 9 kg—24 mg per kg per day in divided doses.
      .
• To help prevent pregnant women from passing HIV to their babies during pregnancy and at birth:
  • For oral dosage form (capsules, syrup):
    • Pregnant women (after 14 weeks of pregnancy, up to the start of labor)—100 milligrams (mg) 5 times a day until the start of labor.
    • Newborn infants—Dose is based on body weight and must be determined by your doctor. The usual dose is 2 milligrams (mg) per kilogram (kg) of body weight every 6 hours starting 12 hours after birth and continuing through 6 weeks of age.
  • For oral dosage form (solution):
    • Pregnant women (after 14 weeks of pregnancy, up to the start of labor)—100 milligrams (mg) 5 times a day, 200 mg every 8 hours, or 300 mg every 12 hours until the start of labor.
    • Newborn infants—Dose is based on body weight and must be determined by your doctor. The usual dose is 2 milligrams (mg) per kilogram (kg) (0.9 mg per pound) of body weight every 6 hours starting within 8 to 12 hours of birth and continuing through 6 weeks of age.

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.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

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

Do not freeze the oral liquid.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

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

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of zidovudine in children.

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of zidovudine in the elderly. However, elderly patients are more likely to have age-related liver, kidney, or heart problems which may require caution and an adjustment in the dose for patients receiving zidovudine.

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of 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 required 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.

• Clarithromycin
• Dapsone
• Doxorubicin
• Doxorubicin Hydrochloride Liposome
• Flucytosine
• Horsetail
• Orlistat
• Pyrazinamide
• Pyrimethamine
• Ribavirin
• Stavudine
• Vinblastine
• Vincristine
• Vincristine Sulfate Liposome

Using this medicine with any of the following medicines may cause an increased 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.

• Acetaminophen
• Fluconazole
• Interferon Beta-1a
• Methadone
• Nelfinavir
• Probenecid
• Rifabutin
• Rifampin
• Rifapentine
• Tipranavir
• Valproic Acid

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

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

• Blood or bone marrow problems (eg, anemia, neutropenia) or
• Muscle problems or
• Obesity (overweight)—Use with caution. May make these conditions worse.

• Kidney disease, severe or
• Liver disease (including hepatitis)—Use with caution. The effects may be increased because of slower removal of the medicine from the body.

• Low amounts of folic acid or vitamin B12 in the blood—Zidovudine may worsen anemia caused by a decrease of folic acid or vitamin B12.

It is very important that your doctor check your or your child's progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Zidovudine may cause blood problems. These problems may result in a greater chance of certain infections and slow healing. Therefore, you should be careful when using regular toothbrushes, dental floss, and toothpicks not to damage your or your child's gums. Check with your or your child's medical doctor or dentist if you have any questions about proper oral hygiene (mouth care) during treatment with this medicine.

Check with your doctor if you or your child has muscle pain, tenderness, wasting, or unusual tiredness or weakness while you are using this medicine.

Zidovudine may cause blood and bone marrow problems. Symptoms of bone marrow problems include fever, chills, sore throat pale skin, or unusual tiredness or weakness. These problems may require blood transfusions or temporarily stopping treatment with zidovudine. Check with your or your child's doctor if any new health problems or symptoms occur while you or your child are taking zidovudine.

Two rare but serious reactions to this medicine are lactic acidosis (too much acid in the blood) and liver toxicity, which includes an enlarged liver. These are more common if you are female, very overweight (obese), or have been taking anti-HIV medicines for a long time. Call your doctor right away if you or your child have more than one of these symptoms: abdominal discomfort or cramping, dark urine, decreased appetite, diarrhea, general feeling of discomfort, light-colored stools, muscle cramping or pain, nausea, unusual tiredness or weakness, trouble breathing, vomiting, or yellow eyes or skin.

Your immune system may get stronger when you start taking HIV medicines. Tell your doctor right away if you or your child notices any changes in your health. Sometimes the immune system will start to fight infections that were hidden in your body, such as pneumonia or tuberculosis. Autoimmune disorders (eg, Graves' disease, polymyositis, or Guillain-Barré syndrome) may also occur.

This medicine may decrease or lose body fat, especially in your face, arms, legs, or buttocks, when this medicine is used for a long time. Talk to your doctor if you have concerns.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.