In the U.S.—

In Canada—

Another commonly used name is AZT.

• Antiviral, systemic

Zidovudine (zye-DOE-vue-deen) (also known as AZT) is used in combination with other anti-virus medicines in the treatment of the infection caused by the human immunodeficiency virus (HIV). HIV is the virus responsible for 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 also is 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 usually related to 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.

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

Zidovudine is available only with your doctor's prescription, in the following dosage forms:

Oral
• Capsules (U.S. and Canada)
• Oral solution (U.S. and Canada)
• Tablets (U.S. and Canada)

Parenteral
• Injection (U.S. and Canada)

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 zidovudine, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to zidovudine. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Zidovudine crosses the placenta. Studies in pregnant women have shown that zidovudine decreases the chance of passing HIV to your baby during pregnancy and at birth. In these studies, zidovudine did not increase the occurrence of birth defects. In most studies in animals, zidovudine has not been shown to cause birth defects except at extremely high doses; however, it has been shown to decrease the number of successful pregnancies in rats and rabbits at doses many times higher than human doses.

Breast-feeding—Zidovudine passes into breast milk. Breast-feeding is usually not recommended in patients with HIV infection because of the risk of passing HIV to the infant.

Children—Zidovudine can cause serious side effects in any patient. Therefore, it is especially important that you discuss with your child's doctor the good that this medicine may do as well as the risks of using it. Your child must be carefully followed, and frequently seen, by the doctor while he or she is taking zidovudine.

Older adults—Zidovudine has not been studied specifically in older people. Therefore, it is not known whether it causes different side effects or problems in the elderly than it does in younger adults.

Other medicines—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 zidovudine, it is especially important that your health care professional know if you are taking any of the following:

• Amphotericin B by injection (e.g., Fungizone) or
• Antineoplastics (cancer medicine) or
• Antithyroid agents (medicine for overactive thyroid) or
• Azathioprine (e.g., Imuran) or
• Chloramphenicol (e.g., Chloromycetin) or
• Colchicine or
• Cyclophosphamide (e.g., Cytoxan) or
• Flucytosine (e.g., Ancobon) or
• Ganciclovir (e.g., Cytovene) or
• Interferon (e.g., Intron A, Roferon-A) or
• Mercaptopurine (e.g., Purinethol) or
• Methotrexate (e.g., Mexate) or
• Plicamycin (e.g., Mithracin)—Caution should be used if these medicines and zidovudine are used together; taking zidovudine while you are using or receiving these medicines may make anemia and other blood problems worse

• Clarithromycin (e.g., Biaxin)—Clarithromycin may decrease the amount of zidovudine in the blood

• Combination drugs that contain zidovudine (e.g., Combivir, Trizivir)—May increase the amount of zidovudine in the blood, increasing the chance of side effects

• Probenecid (e.g., Benemid)—Probenecid may increase the amount of zidovudine in the blood, increasing the chance of side effects

• Doxorubicin (e.g., Adriamycin) or
• Ribavirin (e.g., Virazole)— These medicines may cause zidovudine to be less effective

• Anemia or other blood problems—Zidovudine may make these conditions worse

• Liver disease—Patients with liver disease may have an increase in side effects from zidovudine

• 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

• At risk for liver disease, or
• Obesity, or
• Taking medicines called nucleosides for a long time—Zidovudine may increase the chance for liver disease

Patient information sheets about zidovudine are available. Read this information carefully.

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.

Keep taking zidovudine for the full time of treatment , even if you begin to feel better.

For patients using zidovudine oral solution:

• 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, check with your health care professional.

Dosing—

The dose of zidovudine 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 zidovudine. If your dose is different, do not change it unless your doctor tells you to do so.

• For the treatment of HIV infection:
  • For oral dosage forms (capsules, oral solution, and tablets):
    • Adults and children 12 years of age and older—600 milligrams (mg) a day in divided doses in combination with other anti-virus medicine.
    • Children up to 12 years of age—Dose is based on body weight or body size and must be determined by your doctor. Zidovudine is given in combination with other anti-virus medicine.
  • For injection dosage form:
    • Adults and teenagers—Dose is based on body weight and must be determined by your doctor. The usual dose is 1 to 2 mg per kilogram (kg) (0.45 to 0.9 mg per pound) of body weight, injected slowly into a vein every four hours five to six times a day. The injection dosage form is given until you can take zidovudine by mouth.
    • Children up to 12 years of age—Dose is based on body weight or body size and must be determined by your doctor.
• To help prevent pregnant women from passing HIV to their babies during pregnancy and at birth:
  • For capsule dosage form:
    • Pregnant women (after 14 weeks of pregnancy, up to the start of labor)—100 milligrams (mg) five times a day, 200 mg every eight hours, or 300 mg every twelve hours until the start of labor.
  • For oral solution dosage form:
    • Pregnant women (after 14 weeks of pregnancy, up to the start of labor)—100 milligrams (mg) five times a day, 200 mg every eight hours, or 300 mg every twelve hours until the start of labor.
    • Newborn infants—Dose is based on body weight and must be determined by your doctor. The usual dose of oral solution is 2 mg per kilogram (kg) (0.9 mg per pound) of body weight every six hours starting within eight to twelve hours of birth and continuing through six weeks of age.
  • For injection dosage form:
    • Pregnant women (during labor and delivery)—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 infused into a vein over the first hour, followed by 1 mg per kg (0.45 mg per pound) of body weight infused into a vein each hour until the umbilical cord is clamped.
    • Newborn infants—If the infant is unable to receive zidovudine oral solution, the injection form may be used instead. Dose is based on body weight and must be determined by your doctor. The usual dose is 1.5 mg per kilogram (kg) (0.7 mg per pound) of body weight every six hours.

Missed dose—

If you do 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—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store capsule in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

It is very important that your doctor check your progress at regular visits. This medicine may cause blood problems.

Do not take any other medicines without checking with your doctor first. To do so may increase the chance of side effects from zidovudine.

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 gums. Check with your medical doctor or dentist if you have any questions about proper oral hygiene (mouth care) during treatment.

HIV may be acquired from or spread to other people through infected body fluids, including blood, vaginal fluid, or semen. If you are infected, it is best to avoid any sexual activity involving an exchange of body fluids with other people. If you do have sex, always wear (or have your partner wear) a condom (“rubber”). Only use condoms made of latex, and use them every time you have vaginal, anal, or oral sex. The use of a spermicide (such as nonoxynol-9) may also help prevent the spread of HIV if it is not irritating to the vagina, rectum, or mouth. Spermicides have been shown to kill HIV in lab tests. Do not use oil-based jelly, cold cream, baby oil, or shortening as a lubricant—these products can cause the condom to break. Lubricants without oil, such as K-Y Jelly, are recommended. Women may wish to carry their own condoms. Birth control pills and diaphragms will help protect against pregnancy, but they will not prevent someone from giving or getting the AIDS virus. If you inject drugs, get help to stop. Do not share needles with anyone. In some cities, more than half of the drug users are infected, and sharing even one needle can spread the virus. If you have any questions about this, check with your health care professional.

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

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

• More common
  • Fever, chills, or sore throat;  pale skin;  unusual tiredness or weakness 
  
  

  The above side effects may also occur up to weeks or months after you stop taking this medicine.

• Rare
  • Abdominal discomfort;  confusion;  convulsions (seizures);  diarrhea;  fast, shallow breathing;  general feeling of discomfort;  loss of appetite;  mood or mental changes;  muscle pain, tenderness, weakness, or cramping;  nausea;  shortness of breath;  sleepiness 
  
  

Other 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. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Difficulty having a bowel movement (stool);  general feeling of discomfort or illness; ;  headache (severe);  lack or loss of strength;  muscle soreness;  nausea;  trouble in sleeping;  vomiting;  weight loss 
  
  

• Less common
  • Bluish-brown colored bands on nails;  changes in skin color 
  
  

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

• Incidence unknown
  • acid or sour stomach;  belching;  burning, tingling, numbness or pain in the hands, arms, feet, or legs; sensation of pins and needles, stabbing pain;  heartburn;  muscle or bone pain;  indigestion;  stomach cramps;  stomach pain;  yellow eyes or skin 
  
  

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although this use is not included in product labeling, zidovudine is used in certain patients with the following medical condition:

• Human immunodeficiency virus (HIV) infection due to occupational exposure (possible prevention of)

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for this use.