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.

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