ZIDOVUDINE (Systemic)

Some commonly used brand names are:

In the U.S.?

• Retrovir

In Canada?

• Apo-Zidovudine
• Novo-AZT
• Retrovir

Another commonly used name is AZT.

Category

• Antiviral, systemic

Description

Zidovudine (zye-DOE-vue-deen) (also known as AZT)is used in combination with other anti-virus medicines in the treatment ofthe infection caused by the human immunodeficiency virus (HIV). HIV is thevirus responsible for acquired immune deficiency syndrome (AIDS). Zidovudineis used to slow the progression of disease in patients infected with HIV whohave advanced symptoms, early symptoms, or no symptoms at all. This medicinealso is used to help prevent pregnant women who have HIV from passing thevirus to their babies during pregnancy and at birth.

Zidovudine will not cure or prevent HIV infection or AIDS; however, ithelps keep HIV from reproducing and appears to slow down the destruction ofthe immune system. This may help delay the development of problems usuallyrelated to AIDS or HIV disease. Zidovudine will not keep you from spreadingHIV to other people. People who receive this medicine may continue to havethe 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; paleskin; and unusual tiredness or weakness. These problems may require bloodtransfusions or temporarily stopping treatment with zidovudine. Check with your doctor if any new health problems or symptoms occur whileyou are taking zidovudine.

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

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

Parenteral
• Injection (U.S. and Canada)

Before Using This Medicine

In deciding to use a medicine, therisks 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 followingshould be considered:

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

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

Breast-feeding?Zidovudine passes into breast milk. Breast-feedingis usually not recommended in patients with HIV infection because of the riskof passing HIV to the infant.

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

Older adults?Zidovudine has not been studied specifically in olderpeople. Therefore, it is not known whether it causes different side effectsor problems in the elderly than it does in younger adults.

Other medicines?Althoughcertain medicines should not be used together at all, in other cases two differentmedicines may be used together even if an interaction might occur. In thesecases, your doctor may want to change the dose, or other precautions may benecessary. When you are taking zidovudine, it is especially important thatyour 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 thesemedicines and zidovudine are used together; taking zidovudine while you areusing or receiving these medicines may make anemia and other blood problemsworse

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

• Combination drugs that contain zidovudine (e.g., Combivir, Trizivir)?Mayincrease the amount of zidovudine in the blood, increasing the chance of sideeffects

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

• Doxorubicin (e.g., Adriamycin) or
• Ribavirin (e.g., Virazole)? These medicines may cause zidovudineto be less effective

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

• Anemia or other blood problems?Zidovudine may make these conditionsworse

• Liver disease?Patients with liver disease may have an increasein side effects from zidovudine

• Low amounts of folic acid or vitamin B₁₂in the blood?Zidovudine may worsen anemia caused by a decrease of folicacid or vitamin B₁₂

• At risk for liver disease, or
• Obesity, or
• Taking medicines called nucleosides for a long time?Zidovudinemay increase the chance for liver disease

Proper Use of This Medicine

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 takeit for a longer time than your doctor ordered. Also, do not stop taking thismedicine 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 measureeach dose accurately. The average household teaspoon may not hold the rightamount 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 withyour health care professional.

Dosing?The dose ofzidovudine will be different for different patients. Follow your doctor's orders or the directions on the label. The followinginformation includes only the average doses of zidovudine. If your dose is different, do not change it unless your doctor tellsyou to do so.

• For the treatment of HIV infection:
  • For oral dosage forms (capsules, oralsolution, 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 weightor body size and must be determined by your doctor. Zidovudine is given incombination with other anti-virus medicine.
  • For injection dosage form:
    • Adults and teenagers?Dose is based on body weight and mustbe 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 everyfour hours five to six times a day. The injection dosage form is given untilyou can take zidovudine by mouth.
    • Children up to 12 years of age?Dose is based on body weightor body size and must be determined by your doctor.
• To help prevent pregnant women from passing HIV to their babies duringpregnancy and at birth:
  • For capsule dosage form:
    • Pregnant women (after 14 weeks of pregnancy, up to the start of labor)?100milligrams (mg) five times a day, 200 mg every eight hours, or 300 mg everytwelve hours until the start of labor.
  • For oral solution dosage form:
    • Pregnant women (after 14 weeks of pregnancy, up to the start of labor)?100milligrams (mg) five times a day, 200 mg every eight hours, or 300 mg everytwelve hours until the start of labor.
    • Newborn infants?Dose is based on body weight and must be determinedby 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 totwelve hours of birth and continuing through six weeks of age.
  • For injection dosage form:
    • Pregnant women (during labor and delivery)?Dose is based onbody 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 veinover the first hour, followed by 1 mg per kg (0.45 mg per pound) of body weightinfused 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 bodyweight and must be determined by your doctor. The usual dose is 1.5 mg perkilogram (kg) (0.7 mg per pound) of body weight every six hours.

Missed dose?If you do miss a dose of this medicine, take itas soon as possible. However, if it is almost time for your next dose, skipthe missed dose and go back to your regular dosing schedule. Do not doubledoses.

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 inother damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be surethat any discarded medicine is out of the reach of children.

Precautions While Using This Medicine

It is very important that yourdoctor check your progress at regular visits. This medicine may causeblood problems.

Do not take any other medicines without checking withyour doctor first. To do so may increase the chance of side effectsfrom zidovudine.

Zidovudine may cause blood problems. These problems may result in a greaterchance of certain infections and slow healing. Therefore, you should be carefulwhen using regular toothbrushes, dental floss, and toothpicks not to damageyour gums. Check with your medical doctor or dentist if you have any questionsabout proper oral hygiene (mouth care) during treatment.

HIV may be acquired from or spread to other people through infected bodyfluids, including blood, vaginal fluid, or semen. Ifyou are infected, it is best to avoid any sexual activity involving an exchangeof body fluids with other people. If you do have sex, always wear (or haveyour partner wear) a condom (?rubber?). Only use condomsmade of latex, and use them every time you have vaginal,anal, or oral sex. The use of a spermicide (such as nonoxynol-9) mayalso 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. Donot use oil-based jelly, cold cream, baby oil, or shortening as a lubricant?theseproducts can cause the condom to break. Lubricants without oil, such as K-Y Jelly, are recommended. Women may wish to carry theirown condoms. Birth control pills and diaphragms will help protect againstpregnancy, but they will not prevent someone from giving or getting the AIDSvirus. If you inject drugs, get help to stop. Do not share needles with anyone. In some cities, morethan half of the drug users are infected, and sharing even one needle canspread the virus. If you have any questions about this, check with your healthcare professional.

Side Effects of This Medicine

Alongwith its needed effects, a medicine may cause some unwanted effects. Althoughnot all of these side effects may occur, if they do occur they may need medicalattention.

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

More common

Fever, chills, or sore throat; paleskin; unusual tiredness or weakness

Note:

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

Rare

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

Other side effects may occurthat usually do not need medical attention. These side effects may go awayduring treatment as your body adjusts to the medicine. However, check withyour 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 younotice any other effects, check with your doctor.

Incidence unknown

Additional Information

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

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

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